DIY slide projector

[Crysist]

I'm interested in making slide projector from a camera and some other light source. I've seen similar things made and sold, most recently a demo of replacing a 4x5 camera back with a light source to make a 4x5 projector. But I'm trying to make a general solution that I can pop behind any camera, where I can sandwich film between the rails and a bright light source acting in place of the pressure plate. Not only does it seem like it'd fit my desire to quickly set up and project my un-mounted film strips, but also because I could do other fun things like do "projection testing" of my lenses, use it with different cameras at a moment's notice, etc. I've done something like this when I try to magnify my phone's flashlight with a lens and observe the image it throws on a wall, but haven't had much success using its relatively weak light for projecting slides. And trying to hold them together.

Furthermore, considering how efficient modern lights are, generating little heat too, would something like a strong flashlight work well? I don't know much else about how slide projectors have to be designed, whether the light needs to be collated or diffuse. Or whether a video light, like the Cinestill lightpad basically is, would work well or better and just needs some kind of condenser. Then just 3D print something that'd hold what I need and a strip of film together and I can press it to the film plane of any camera.

Also, should I aim for a warmer light (closer to halogens color temp) for projection always or is a more neutral light fine?

Has anyone tried something like this or has any suggestions?

 

[koraks]

Furthermore, considering how efficient modern lights are, generating little heat too, would something like a strong flashlight work well?

That's all quite relative. To get in the ballpark of a regular slide projector in terms of illumination, you're still looking at 50W (at the very least) of LED power. The vast majority of that power is going to be dissipated in the light source itself and the optics and housing right in front of it (i.e. your camera). Dumping that amount of power into, let's say, a regular SLR camera (35mm or MF) will likely create problems with melting lubricants, warping of parts etc.

Then just 3D print something that'd hold what I need and a strip of film together and I can press it to the film plane of any camera.

In terms of thermal management regular 3D printed parts (from filament printers) will be a liability as they tend to conform to Dali's watches in close proximity to a high-power LED source.

With a large format camera, you have a fighting chance because of their relatively simple and voluminous/open construction.

 

[Crysist]

That's all quite relative. To get in the ballpark of a regular slide projector in terms of illumination, you're still looking at 50W (at the very least) of LED power. The vast majority of that power is going to be dissipated in the light source itself and the optics and housing right in front of it (i.e. your camera). Dumping that amount of power into, let's say, a regular SLR camera (35mm or MF) will likely create problems with melting lubricants, warping of parts etc.

Damn. Asking experienced people does really show a lot of "fun" project ideas I might have aren't well thought out...

However, don't slide projectors already have a glass layer between the light and the film that blocks a lot of the heat from reaching it? Because, wouldn't the same heat of the light melt/warp the film the exact same way?

 

[koraks]

Asking experienced people does really show a lot of "fun" project ideas I might have aren't well thought out...

So the proper way ahead is to not ask questions and get started! All joking aside, that's what I sometimes do, and it's often a really good way to learn.

However, don't slide projectors already have a glass layer between the light and the film that blocks a lot of the heat from reaching it? Because, wouldn't the same heat of the light melt/warp the film the exact same way?

Yes, but:
1: Slide projectors have a thermal design/layout (including a beefy fan) for this reason. A picture-taking camera doesn't, so you have to take measures to avoid thermal problems in a system not inherently designed to deal with them.
2: The materials and components used in slide projectors are comparatively crude and robust compared to the parts of a typical camera. There's no/less sensitive mechanics involving shutters, optics (mirrors, pentaprisms etc.)
3: Slide 'pop' is indeed a problem with projectors; you generally have to wait 2-3 seconds and then refocus the projector.

So the concerns aren't so much about the film - it's also that, but my main concern is that you'll end up damaging the camera.

 

[Mr Bill]

Hi, actually this whole thing is more complicated than you mighg think. I've done something related... different but using similar optical principles.

Essentially you would have two overlapping optical systems. The first one would "collect" the light from your source (whatever lamp, etc., you are using) and then attempt to funnel this light into your projection lens. Whatever light you cannot get into the projection lens aperture is obviously no use to you, right?

The second system is the one you seem familiar with; the one that focuses an image of your film/slide onto the wall, or whatever. It interacts with the first system in that the film/slide must be in an appropriate place in the first system such that 1) it can be fully illuminated and 2) that all of this illumination will ideally be directed into the aperture of the projection lens. (The projection lens will be at different distances depending on its focal length, etc.)

If you consider something like a condenser enlarger you can see the two systems at work. First you have a lamp that emits light, typically in nearly all directions. A largish condenser lens collects as much light as it can, and then directs this light into the enlarger lens, which will be in different places depending on its focal length and size of the enlargement. (This is the reason why enlargers have things like different condenser configurations for different size negatives.) And obviously (?) an enlarger's condenser(s) must be larger in diameter than the film being used.

Something else worth pointing out is that some enlargers might have a large diffuse light source behind the negative, and that these seem to work ok. Well, that's true, BUT... enlargers are used in the dark, and the exposure times can be increased to whatever might be needed. If they had to be used in some sort of room light, even dim, they would have a hard time overcoming the ambient light.

Regarding your idea to use a "strong flashlight" (aka "torch), this will likely work to some extent. But probably only in a small area near the center of the film/slide. Cuz the light beam has a fairly small diameter.

I'm glad to elaborate more, so feel free to ask questions.

 

[Harry Callahan]

...
but also because I could do other fun things like do "projection testing" of my lenses, use it with different cameras at a moment's notice, etc. ...

. Then just 3D print something that'd hold what I need and a strip of film together and I can press it to the film plane of any camera.

Also, should I aim for a warmer light (closer to halogens color temp) for projection always or is a more neutral light fine?

I don`t know if this "projection testing" would work at all. For whatever reason a projection lens seems not to need that high quality than a taking lens - maybe because the contrast of the slide is high, because of the bright light source inside the projector. Single-coated projection lenses can be pretty sharp and contrasty, when used for projection wide open , while they wouldn`t perform that good as a taking lens - wide open.
So even if your idea would work, you probably couldn`t really test your camera lenses regarding taking quality.

Film inside of a projector should be flat - and film should be parallel to the lens, i doubt you could achieve this with something 3D printed - and again you couldn`t judge the quality of the lens.

Projectors have been using bulbs or halogen lamps for decades, because there wasn`t any better (maybe some high pressure lamps, but these are big and get very warm etc...) regarding color temperature. If there was a classical bulb that could produce daylight temperature, they had taken it decades ago. That`s an advantage of LEDs today - on the other hand the human eye does get used to small color shifts pretty fast, that`s why classical bulbs work too though they produce even warmer light than halogen bulbs.

So even if you could solve the light-source-problem, other problems still were there.

 

[Crysist]

So the proper way ahead is to not ask questions and get started! All joking aside, that's what I sometimes do, and it's often a really good way to learn

Oh, I won't be stopping it for a moment, haha! I just feel silly that there were such big oversights in the way of what I thought would be quite simple! I greatly appreciate yours and everyone else's responses!

Yes, but:
1: Slide projectors have a thermal design/layout (including a beefy fan) for this reason. A picture-taking camera doesn't, so you have to take measures to avoid thermal problems in a system not inherently designed to deal with them.
2: The materials and components used in slide projectors are comparatively crude and robust compared to the parts of a typical camera. There's no/less sensitive mechanics involving shutters, optics (mirrors, pentaprisms etc.)
3: Slide 'pop' is indeed a problem with projectors; you generally have to wait 2-3 seconds and then refocus the projector.

So the concerns aren't so much about the film - it's also that, but my main concern is that you'll end up damaging the camera.

Well then, is it worthwhile if I get a total junk rangefinder and dedicate it to being an impromptu "projector"? Because a projector minus the film advance mechanism would be very useful. My slides are uncut and differing sizes, it'd be nice if there were projectors where you could just slide the film through instead of having them mounted.

Hi, actually this whole thing is more complicated than you mighg think. I've done something related... different but using similar optical principles.

Essentially you would have two overlapping optical systems. The first one would "collect" the light from your source (whatever lamp, etc., you are using) and then attempt to funnel this light into your projection lens. Whatever light you cannot get into the projection lens aperture is obviously no use to you, right?

Yes, that's also what the parabolic mirrors behind the bulbs are for, right? So you're not losing out of the "back half" of light emitted?

The second system is the one you seem familiar with; the one that focuses an image of your film/slide onto the wall, or whatever. It interacts with the first system in that the film/slide must be in an appropriate place in the first system such that 1) it can be fully illuminated and 2) that all of this illumination will ideally be directed into the aperture of the projection lens. (The projection lens will be at different distances depending on its focal length, etc.)

If you consider something like a condenser enlarger you can see the two systems at work. First you have a lamp that emits light, typically in nearly all directions. A largish condenser lens collects as much light as it can, and then directs this light into the enlarger lens, which will be in different places depending on its focal length and size of the enlargement. (This is the reason why enlargers have things like different condenser configurations for different size negatives.) And obviously (?) an enlarger's condenser(s) must be larger in diameter than the film being used.

Something else worth pointing out is that some enlargers might have a large diffuse light source behind the negative, and that these seem to work ok. Well, that's true, BUT... enlargers are used in the dark, and the exposure times can be increased to whatever might be needed. If they had to be used in some sort of room light, even dim, they would have a hard time overcoming the ambient light.

Regarding your idea to use a "strong flashlight" (aka "torch), this will likely work to some extent. But probably only in a small area near the center of the film/slide. Cuz the light beam has a fairly small diameter.

I'm glad to elaborate more, so feel free to ask questions.

Hmm, well then I have two opposite questions. My lightpad (basically a strong video light CS sells rebranded) is very bright and larger than my film, can I condense the light from the larger area into smaller film? Would that be a good light source?

Also, can I flip a condenser around to use against a smaller light source like a flash light? I know that's losing the benefit of the former case, instead of focusing more light into a smaller area, this would spread it out and you'd need quite a strong flashlight.

I don`t know if this "projection testing" would work at all. For whatever reason a projection lens seems not to need that high quality than a taking lens - maybe because the contrast of the slide is high, because of the bright light source inside the projector. Single-coated projection lenses can be pretty sharp and contrasty, when used for projection wide open , while they wouldn`t perform that good as a taking lens - wide open.
So even if your idea would work, you probably couldn`t really test your camera lenses regarding taking quality.

I might not have said this in the clearest way. What I mean by projection testing is assessing a lens, any lens, by projecting a very very fine pattern from the film plane out to the focus plane on the object-side. This seems to be a very common form of rough metrology of lenses. I envisioned I could carry some little flashlight-like device around and test any camera lens by pressing it to the film plane and observing how the projected image looks.

And while projector lenses may not need to be the highest quality to get a great image, there's still a lot you can scrutinize. The corners, certainly. Distortion.

Film inside of a projector should be flat - and film should be parallel to the lens, i doubt you could achieve this with something 3D printed - and again you couldn`t judge the quality of the lens.

Projectors have been using bulbs or halogen lamps for decades, because there wasn`t any better (maybe some high pressure lamps, but these are big and get very warm etc...) regarding color temperature. If there was a classical bulb that could produce daylight temperature, they had taken it decades ago. That`s an advantage of LEDs today - on the other hand the human eye does get used to small color shifts pretty fast, that`s why classical bulbs work too though they produce even warmer light than halogen bulbs.

So even if you could solve the light-source-problem, other problems still were there.

I could get something sent out to be machined, I suppose. All-in-all, the larger goal is merely some more simple slide projector for my own use. To just work off film strips, which I could probably just press against etched glass for both diffusion and ANR. No slide mounts, no transport, just a strong light, a film support, and some way to hold a lens. I could just get a 2ndhand projector lens. Does that sound like a better concept?

The projection testing idea was just a similar idea that I figured would naturally be possible with something like this.

Thank you all for the help!

 

[wiltw]

Is this merely a project, or do you need a slide projector and want one on the cheap? Lots of slide projectors available via trhift stores for not much money.

 

[koraks]

Well then, is it worthwhile if I get a total junk rangefinder and dedicate it to being an impromptu "projector"?

You could definitely give it a go. I expect there will be challenges, but it can be a fun project and I can see how it might end up sort of working.
If you want to limit light falloff in the corners, I think you'll have to tackle the challenge of collimation of the light as @Mr Bill also mentioned.

 

[Harry Callahan]

...

Well then, is it worthwhile if I get a total junk rangefinder and dedicate it to being an impromptu "projector"? Because a projector minus the film advance mechanism would be very useful. My slides are uncut and differing sizes, it'd be nice if there were projectors where you could just slide the film through instead of having them mounted.


...


I might not have said this in the clearest way. What I mean by projection testing is assessing a lens, any lens, by projecting a very very fine pattern from the film plane out to the focus plane on the object-side. This seems to be a very common form of rough metrology of lenses. I envisioned I could carry some little flashlight-like device around and test any camera lens by pressing it to the film plane and observing how the projected image looks.

And while projector lenses may not need to be the highest quality to get a great image, there's still a lot you can scrutinize. The corners, certainly. Distortion.


I could get something sent out to be machined, I suppose. All-in-all, the larger goal is merely some more simple slide projector for my own use. To just work off film strips, which I could probably just press against etched glass for both diffusion and ANR. No slide mounts, no transport, just a strong light, a film support, and some way to hold a lens. I could just get a 2ndhand projector lens. Does that sound like a better concept?

The projection testing idea was just a similar idea that I figured would naturally be possible with something like this.

Thank you all for the help!

There were film-strip slide projectors... in the 50s i think. There also were multiformat slide projectors, being for 6x6 but having an exchangable holder for 35mm slides - some even having an exchangable film-strip holder for 35mm. Havn`t seen a film-strip projector for uncut medium format film though.
Otherwise get an enlarger for whatever your biggest slide format is. Turn it to a wall - and viola you can project any slide strips you have. The enlarger should have glass holder and masks for different slide sizes, a swing head, and rather fast lenses matching format by focal length - but then you had an all-in-one multiformat-film-strip slide projector.

I get what you mean. You want a small device you can test the lens of a camera with by turning the camera into a projector - so you can judge lens quality on a flea market for example.

Also if you have something machined, it may have the required precision, but it also should not scratch the film rails in the camera you press it against. There are problems and problems.
I don`t think that`ll work, due to the reasons mentioned. Even if, you needed a high quality testing slide inside the camera. Some film can resolve up to 150ll/mm and your test slide had to have this sharpness - up into the edges. Your light source had to be very even in illumination so you can check brightness fall off of the camera lens into the edges.
You needed a very dark room with a white, unstructured wall to project the image on. If the lens can resolve 100ll/mm, you`d have to enlarge by x100 to have one line on the film to be 1mm on the screen. If you enlarge a 35mm neg by x100 you end up with a picture being 3,6m or about 12feet wide. Then you can judge whether the lens does 100ll/mm or not. You needed a strong light source to project 35mm to 12feet, a dark room and a big wall or screen. Also the camera had to be on a tripod, as you cannot hold the camera still enough to enlarge by x100 and see 1mm on the screen sharp. Also, when enlarging 35mm by x100 the distance between camera and screen is (usually, for wide angle lenses it was less) so big that you cannot judge sharpness of the projected image when holding the camera. You had to move closer to the screen, while the camera had to remain distant to the screen. The camera body had to be parallel to the screen or the image would get unsharp edges - though the lens may be excellent.
...

And even if you'd get all this right - imagine you going to a flea market or camera store, asking the seller to open the camera so you can press a home-built apparatus into the back of the camera... into a camera you *might* buy.

I get your idea, it was great if it worked (easily), but i`m afraid it wouldn`t work (easily) - if it did such devices were around for decades or even a century.
Get a film-strip projector or turn an enlarger into a multiformat projector. Lens test on the fly...

EDIT:
Ok, you needed an enlarger with some sort of "double-swing-head" so you can switch between horizontal and vertical format. That would be a problem. On the other hand i don`t know if these film-strip slide projectors did have a swing head... maybe these were fixed too...

 

[koraks]

and viola

A viola is a type of violin, slightly larger, with a C string on the low end instead of the violin's E-string on the high end. "Voila" is a French exclamation that translates as "see there".

 

[Crysist]

Is this merely a project, or do you need a slide projector and want one on the cheap? Lots of slide projectors available via trhift stores for not much money.

You could definitely give it a go. I expect there will be challenges, but it can be a fun project and I can see how it might end up sort of working.

Right, it's not just to get a slide projector, but rather something more useful for my situation. I have multiple formats I'm interested in projecting (35mm, half-frame, submini) and want to avoid needing to do any mounting. And I'm feeling the weight of getting more and more photography stuff and am trying to be a bit more wary of large items lol

If you want to limit light falloff in the corners, I think you'll have to tackle the challenge of collimation of the light as @Mr Bill also mentioned.

Could a simple Fresnel lens work for that purpose, or are proper condensers more elaborate and I should use an existing one?

There were film-strip slide projectors... in the 50s i think. There also were multiformat slide projectors, being for 6x6 but having an exchangable holder for 35mm slides - some even having an exchangable film-strip holder for 35mm. Havn`t seen a film-strip projector for uncut medium format film though.
Otherwise get an enlarger for whatever your biggest slide format is. Turn it to a wall - and viola you can project any slide strips you have. The enlarger should have glass holder and masks for different slide sizes, a swing head, and rather fast lenses matching format by focal length - but then you had an all-in-one multiformat-film-strip slide projector.

That actually sounds like a very great idea! Heck, I could even get a color head and do live color correction as well, lol

I've shot rather little MF though, so I probably won't have a big need to project it. Additionally, what I last shot on 6x6 had some bad focus errors cause I used a Super Ikonta whose lens wasn't parallel with the film plane. It's been relegated to a shelf for now.

Does the output of the bulbs in an enlarger differ from a slide projector? I'd imagine that it'd be less powerful because you have the benefit of time when printing, while when projecting you want to be able to output through higher density positives and project them over a larger area. Maybe changing the bulb would help in that case.

I get what you mean. You want a small device you can test the lens of a camera with by turning the camera into a projector - so you can judge lens quality on a flea market for example.

Right, exactly, just making sure! Or even testing my own stuff. It merely seems easier to judge than the opposite case, if you had some gate-focuser like device that you'd pop on the film plane and instead analyze the aerial image formed by the lens. I do that in a very casual sense sometimes by holding a loupe at the backside of a lens (if it can be unmounted from a camera), but again those are differences that are not visible at that scale.

Also if you have something machined, it may have the required precision, but it also should not scratch the film rails in the camera you press it against. There are problems and problems.
I don`t think that`ll work, due to the reasons mentioned. Even if, you needed a high quality testing slide inside the camera. Some film can resolve up to 150ll/mm and your test slide had to have this sharpness - up into the edges. Your light source had to be very even in illumination so you can check brightness fall off of the camera lens into the edges.
You needed a very dark room with a white, unstructured wall to project the image on. If the lens can resolve 100ll/mm, you`d have to enlarge by x100 to have one line on the film to be 1mm on the screen. If you enlarge a 35mm neg by x100 you end up with a picture being 3,6m or about 12feet wide. Then you can judge whether the lens does 100ll/mm or not. You needed a strong light source to project 35mm to 12feet, a dark room and a big wall or screen. Also the camera had to be on a tripod, as you cannot hold the camera still enough to enlarge by x100 and see 1mm on the screen sharp. Also, when enlarging 35mm by x100 the distance between camera and screen is (usually, for wide angle lenses it was less) so big that you cannot judge sharpness of the projected image when holding the camera. You had to move closer to the screen, while the camera had to remain distant to the screen. The camera body had to be parallel to the screen or the image would get unsharp edges - though the lens may be excellent.
...

Those are very good points, but some of it isn't quite impractical. When I project the image of my phone's flashlight against a wall, just handholding a lens, I am able to hold it on okay focus just with my hands. I can blow up the light shining through the Fresnel like surface with lines 0.1-0.2mm apart to be nearly 1 cm apart at a very close range. I can tell the differences in stopping down on spherical aberration and contrast quite well. But you're very correct, I needed to do this in my room with the lights out. Also since I used my phone I can't share a pic of the fun projection trick with my friends lol

Another idea I thought of was to find some kind of transparent "test target". First I was just trying some film itself but I couldn't hold them all aligned with my hands, and the light was far too weak. Instead, noticing test targets are pretty expensive, I bought a glass microscope scale reference slide. It just shows some 1/100 mm divisions in the middle. Holding this together is hard too, but I've made good use of it taping it to the film place of a camera and checking infinity focus on it by pointing another camera focused on infinity at the lens and seeing if the scale was sharp behind the lens.

I had also thought about using a laser in some way, much smaller area but far stronger. Something like those little laser projector pens that shoot a tiny image on the wall. Haven't tried that yet.

So your main points about struggles to overcome are right, but I see some value possible with a setup like that.

And even if you'd get all this right - imagine you going to a flea market or camera store, asking the seller to open the camera so you can press a home-built apparatus into the back of the camera... into a camera you *might* buy.

I get your idea, it was great if it worked (easily), but i`m afraid it wouldn`t work (easily) - if it did such devices were around for decades or even a century.

Hey - I have bothered my local camera shop guy successfully quite a lot thankyouverymuch!

Most of what I check out are free to pick up and look through, test, etc. Of course, with the shop owner knowing. So, perhaps I'm more focused on the lenses I own, lets say.

And projection testers do exist of course. Just not tiny!

Get a film-strip projector or turn an enlarger into a multiformat projector. Lens test on the fly...

EDIT:
Ok, you needed an enlarger with some sort of "double-swing-head" so you can switch between horizontal and vertical format. That would be a problem. On the other hand i don`t know if these film-strip slide projectors did have a swing head... maybe these were fixed too...

You mean whether the part you slot the film into being able to be rotated by 90 degrees? So as to right an image that was taken in a different orientation? Is that required for enlargers if you can just rotate the paper instead? I last used an enlarger 15 years ago, I forget if the negative holder could be turned on the ones I used.

Right, normal slide projectors do have the advantage that the slide mounts are square, you can just turn each to make the image upright, so that wasn't needed.

A viola is a type of violin, slightly larger, with a C string on the low end instead of the violin's E-string on the high end. "Voila" is a French exclamation that translates as "see there".

You're even helpful on such minor things, haha! Sometimes I think "oh, I hope someone like one of the mods or someone very experienced replies to my post/thread with the answer" but end up surprised at how active you all actually are! C:

 

[koraks]

Could a simple Fresnel lens work for that purpose, or are proper condensers more elaborate and I should use an existing one?

I expect you could construct a good enough condenser using a pair of fresnels.

You're even helpful on such minor things, haha!

Ah, it was pedantry really, but as an ex/recovering violinist (not a violist!), the 'viola' mistake constitutes an itch that I find difficult not to scratch. I also find it somewhat hilarious as it brings up the image of an old-fashioned waiter with a white napkin over one arm held to his body while with the other hand triumphantly thrusting a viola in someone's face, screaming "VIOLA!!"

 

[Harry Callahan]

A viola is a type of violin, slightly larger, with a C string on the low end instead of the violin's E-string on the high end. "Voila" is a French exclamation that translates as "see there".

Ah, ok. I meant the French exclamation.

...

That actually sounds like a very great idea! Heck, I could even get a color head and do live color correction as well, lol

I've shot rather little MF though, so I probably won't have a big need to project it. Additionally, what I last shot on 6x6 had some bad focus errors cause I used a Super Ikonta whose lens wasn't parallel with the film plane. It's been relegated to a shelf for now.

Does the output of the bulbs in an enlarger differ from a slide projector? I'd imagine that it'd be less powerful because you have the benefit of time when printing, while when projecting you want to be able to output through higher density positives and project them over a larger area. Maybe changing the bulb would help in that case.

...

Enlargers usually have weaker bulbs and slower lenses, so it does depend on how big you want to project. Depending on what enlarger you have/get you could put in a stronger bulb (LED also should be possible) and adapt a faster projection lens to it.

...

Right, exactly, just making sure! Or even testing my own stuff. It merely seems easier to judge than the opposite case, if you had some gate-focuser like device that you'd pop on the film plane and instead analyze the aerial image formed by the lens. I do that in a very casual sense sometimes by holding a loupe at the backside of a lens (if it can be unmounted from a camera), but again those are differences that are not visible at that scale.


Those are very good points, but some of it isn't quite impractical. When I project the image of my phone's flashlight against a wall, just handholding a lens, I am able to hold it on okay focus just with my hands. I can blow up the light shining through the Fresnel like surface with lines 0.1-0.2mm apart to be nearly 1 cm apart at a very close range. I can tell the differences in stopping down on spherical aberration and contrast quite well. But you're very correct, I needed to do this in my room with the lights out. Also since I used my phone I can't share a pic of the fun projection trick with my friends lol

...

I don`t know if the aerial image would help you ahead. There are movie cameras, S8 cameras, which have an aerial reflex finder, but looking through it won`t tell you how good or bad the camera lens will perform. You could put a ground glass on the film plane, but apart from scratching the film plane of the camera, a ground glass has grain and this grain will prevent you from judging sharpness of the lens (unless its a really bad lens).

Ok, then you have really steady hands - but if you enlarge 0.1mm to 1cm you have an enlargement factor of 100, what focal length did the lens have? You say Fresnel surface, do you mean the light of your phone having a Fresnel like surface? If so, does the light have some sort of lens in front?

...

Another idea I thought of was to find some kind of transparent "test target". First I was just trying some film itself but I couldn't hold them all aligned with my hands, and the light was far too weak. Instead, noticing test targets are pretty expensive, I bought a glass microscope scale reference slide. It just shows some 1/100 mm divisions in the middle. Holding this together is hard too, but I've made good use of it taping it to the film place of a camera and checking infinity focus on it by pointing another camera focused on infinity at the lens and seeing if the scale was sharp behind the lens.

I had also thought about using a laser in some way, much smaller area but far stronger. Something like those little laser projector pens that shoot a tiny image on the wall. Haven't tried that yet.

So your main points about struggles to overcome are right, but I see some value possible with a setup like that.

...

Did you try to project this microscope scale? This would show how good or bad it works. Lasers could be problematic again as they concentrate a lot of energy on a small area. Projector pens probably not, but if you find these to be too weak you again run into danger of damaging the camera.

...

You mean whether the part you slot the film into being able to be rotated by 90 degrees? So as to right an image that was taken in a different orientation? Is that required for enlargers if you can just rotate the paper instead? I last used an enlarger 15 years ago, I forget if the negative holder could be turned on the ones I used.

Right, normal slide projectors do have the advantage that the slide mounts are square, you can just turn each to make the image upright, so that wasn't needed.

...

Yes. I`m not into these film-strip projectors, maybe there were some where you could rotate the film holder - but if you decide to get one check this before you buy.
Some enlargers can rotate their head, so they don`t project the image down on the easel but to the wall, but enlargers cannot rotate the negative holder - and that`s what you needed to project different orientations on a film-strip.

Slides mean some work as you have to mount them, but then you`re good. You can change orientation, order, blown shots and even format. If you have a 6x6 projector you also can adapt 35mm slides into the mount - or even smaller formats.

...

I also find it somewhat hilarious as it brings up the image of an old-fashioned waiter with a white napkin over one arm held to his body while with the other hand triumphantly thrusting a viola in someone's face, screaming "VIOLA!!"

Sometimes i`m exactly in this mood... but i am not sure if i was when i made this typo...

 

[Crysist]

I expect you could construct a good enough condenser using a pair of fresnels.

A pair of lenses are needed? I mean, I know that single elements are very limited in terms of quality, but wouldn't putting a light source at the focal point of a lens be enough to collimate it?

I suppose that's good in my case, as when I went to buy a fresnel lens on ebay, a seller sold them in pairs so I have two.

Ah, it was pedantry really, but as an ex/recovering violinist (not a violist!), the 'viola' mistake constitutes an itch that I find difficult not to scratch. I also find it somewhat hilarious as it brings up the image of an old-fashioned waiter with a white napkin over one arm held to his body while with the other hand triumphantly thrusting a viola in someone's face, screaming "VIOLA!!"

ELEGANT!!!

Enlargers usually have weaker bulbs and slower lenses, so it does depend on how big you want to project. Depending on what enlarger you have/get you could put in a stronger bulb (LED also should be possible) and adapt a faster projection lens to it.

Right, I figured. But if it is easy to swap that might be okay! Also, besides the shape being perhaps odd and needing to swap out a the bulb/lens, are there any other main things to look out for? Or do you suppose that's a good enough setup?

I don`t know if the aerial image would help you ahead. There are movie cameras, S8 cameras, which have an aerial reflex finder, but looking through it won`t tell you how good or bad the camera lens will perform. You could put a ground glass on the film plane, but apart from scratching the film plane of the camera, a ground glass has grain and this grain will prevent you from judging sharpness of the lens (unless its a really bad lens).

I thought that's the point and thus the advantage, no? Avoiding ground glass just as you can avoid using film to assess a lens in isolation. GG is definitely important for finding and assessing the plane of focus in particular, but I don't mean to do that for judging the quality that much.

Oh, and I never knew some cameras had such reflex finders! That's very interesting! I figure it's much easier because, from such tiny lenses, you can capture more of the light from the exit pupil to show the operator. Meanwhile, for larger lenses you only see a smaller exit pupil, and to get the entire field of view of the lens you have to look back along the axis the light came from. To get the light that strikes the far edge of the film, you need to be focused at the film plane at that point and point towards the exit pupil.

I've seen old documentary shorts from Kodak and others on making cameras and lenses, and when they get to showing how they assess the quality of them, among other techniques like projection out the test lens, one is where they mount the lens on a special microscope. The focal point of the microscope objective seems to be at the film plane and the operator can swivel the microscope about the back half of the lens. I think one use of this and similar tests was for centering and setting focus (besides using a collimator).

Ok, then you have really steady hands - but if you enlarge 0.1mm to 1cm you have an enlargement factor of 100, what focal length did the lens have? You say Fresnel surface, do you mean the light of your phone having a Fresnel like surface? If so, does the light have some sort of lens in front?

I redid it just to verify. I can cup a 50mm lens (specifically a Contax 50/1.5 Sonnar) in my hand, put it in front of my phone's flashlight, usually resting my cupped hand against my phone, and project and image on the wall 5-10ft away in a dark room. At that distance they're enlarged closer to 5mm, but I am able to point it out the door to another room's wall that's around 20ft away. Then the details are around 1cm in diameter.

I have a Samsung Galaxy Note 20, there's an image on the Samsung website which shows it just close enough to start to see the surface texture. There doesn't seem to be an actual lens, just a layer of glass over what you see.

For reference, the flash is 4mm across. I used a measuring microscope with 1/2000'' divisions and counted the width of each "ring", the upward or downward slope of the surface, to be 5 divisions in width to correlate to what shows up as a solid ring on the wall. That's around 0.06mm.

Unfortunately, the light is so close to the cameras that I can't take a picture of the image I project. And my old phone's battery died, so this is the only digital camera I have with me currently :/

Did you try to project this microscope scale? This would show how good or bad it works. Lasers could be problematic again as they concentrate a lot of energy on a small area. Projector pens probably not, but if you find these to be too weak you again run into danger of damaging the camera.

I did! I was able to make the scale project through the lens far more easily.

Also, aren't lasers and lenses more dangerous if they create a smaller point of focus than the laser? I think most examples where people's sensors get fried at laser light shows, they magnification ratio is probably so low that the already bright lasers get squeezed onto a far far tighter area and thus become dangerous. How can this be a problem inside the lens though? Or coming from the rear of the lens, where it will be magnified?

Yes. I`m not into these film-strip projectors, maybe there were some where you could rotate the film holder - but if you decide to get one check this before you buy.
Some enlargers can rotate their head, so they don`t project the image down on the easel but to the wall, but enlargers cannot rotate the negative holder - and that`s what you needed to project different orientations on a film-strip.

You don't like them? They seem to also do a good job at fitting my needs. I just don't know if they were a lesser-quality option and might offer less options for upgrading. But in terms of being the rather simple layout I was thinking about, something that would also just accept smaller formats, they look like a good option. And aren't too expensive.

I suppose the remaining question is which would likely be better, a filmstrip projector or an enlarger head? Hmm. I suppose I can just try both.

Slides mean some work as you have to mount them, but then you`re good. You can change orientation, order, blown shots and even format. If you have a 6x6 projector you also can adapt 35mm slides into the mount - or even smaller formats.

The destructive aspect never sat well with me. Especially as I've massacred a cut between frames a handful of times when cutting strips to put in sleeves. Even after getting a film slicer to use instead of a scissor, I still occasionally get one that the slicer doesn't cut through and damages the emulsion at the end of the cut.

Sometimes i`m exactly in this mood... but i am not sure if i was when i made this typo...

Consider yourself lucky that you weren't part of the group who had no clue how to spell it and thought it began with a W!

 

[Harry Callahan]

...

Right, I figured. But if it is easy to swap that might be okay! Also, besides the shape being perhaps odd and needing to swap out a the bulb/lens, are there any other main things to look out for? Or do you suppose that's a good enough setup?


I thought that's the point and thus the advantage, no? Avoiding ground glass just as you can avoid using film to assess a lens in isolation. GG is definitely important for finding and assessing the plane of focus in particular, but I don't mean to do that for judging the quality that much.

...

If you use an enlarger you only can project vertical format, if you have 35mm film strips. In theory you could built a different column, which has a 90° angle at the top end, then you had the head in a position to project on the wall and you could swing the head for vertical and horizontal images on the strip.

With these S8 cameras it is not about assessing the (technical) quality of a lens, but to have a less distracting image in the viewfinder. If the viewfinder did have a ground glass the grain of the glass would distract to some extend - that`s probably why many S8 cameras have an aerial image only.

...

Oh, and I never knew some cameras had such reflex finders! That's very interesting! I figure it's much easier because, from such tiny lenses, you can capture more of the light from the exit pupil to show the operator. Meanwhile, for larger lenses you only see a smaller exit pupil, and to get the entire field of view of the lens you have to look back along the axis the light came from. To get the light that strikes the far edge of the film, you need to be focused at the film plane at that point and point towards the exit pupil.

I've seen old documentary shorts from Kodak and others on making cameras and lenses, and when they get to showing how they assess the quality of them, among other techniques like projection out the test lens, one is where they mount the lens on a special microscope. The focal point of the microscope objective seems to be at the film plane and the operator can swivel the microscope about the back half of the lens. I think one use of this and similar tests was for centering and setting focus (besides using a collimator).

...

S8 cameras often don`t have tiny lenses. Quite some have lenses that are longer than a 50mm lens for 35mm still.
I don`t know how to test lenses for quality other than doing test shots - i just wanted to point out that an aerial image probably won`t help you ahead. Especially when light is low the image in the viewfinder of a S8 camera looks better than what you capture on the film.

...


I redid it just to verify. I can cup a 50mm lens (specifically a Contax 50/1.5 Sonnar) in my hand, put it in front of my phone's flashlight, usually resting my cupped hand against my phone, and project and image on the wall 5-10ft away in a dark room. At that distance they're enlarged closer to 5mm, but I am able to point it out the door to another room's wall that's around 20ft away. Then the details are around 1cm in diameter.

I have a Samsung Galaxy Note 20, there's an image on the Samsung website which shows it just close enough to start to see the surface texture. There doesn't seem to be an actual lens, just a layer of glass over what you see.

View attachment 400230

For reference, the flash is 4mm across. I used a measuring microscope with 1/2000'' divisions and counted the width of each "ring", the upward or downward slope of the surface, to be 5 divisions in width to correlate to what shows up as a solid ring on the wall. That's around 0.06mm.

Unfortunately, the light is so close to the cameras that I can't take a picture of the image I project. And my old phone's battery died, so this is the only digital camera I have with me currently :/


I did! I was able to make the scale project through the lens far more easily.

...

Hm... it looks to me that there is some sort of Fresnel lens on the light of you phone. If you shine this through a camera lens it probably will interact optically and may give you a different enlarging (factor) than a negative or slide.
On the other hand if you can make 0.06mm to about 1 cm you`re having quite an enlargement factor there.

When you projected the scale, did you get about the same enlargement of the divisions on the wall like 5mm or 1cm?

...

Also, aren't lasers and lenses more dangerous if they create a smaller point of focus than the laser? I think most examples where people's sensors get fried at laser light shows, they magnification ratio is probably so low that the already bright lasers get squeezed onto a far far tighter area and thus become dangerous. How can this be a problem inside the lens though? Or coming from the rear of the lens, where it will be magnified?

...

Yes, but lenses usually concentrate light at the focal point. That`s why you still get an image on your film up to the edges when the aperture is stopped down.
But my point rather is that lenses also can suffer heat damage. Someone once told me that there were problems when a light head for 4x5 cameras was offered - to convert the 4x5 camera into an enlarger. They used the taking lens on the camera, but the light head apparently produced enough heat to somewhat damage the (taking) lens.
Also cameras on display, close to a window with the sun shining into the lenses for hours every day can suffer lens damage. This of course does take a while and may not apply to every lens, but if you use a laser to point only at a section of the lens you may introduce too much heat/energy onto that spot of the lens and damage the coating or even the glass.
And as you point the laser on lenses some of which will concentrate the laser beam even more... i got a bad feeling about that.

...

You don't like them? They seem to also do a good job at fitting my needs. I just don't know if they were a lesser-quality option and might offer less options for upgrading. But in terms of being the rather simple layout I was thinking about, something that would also just accept smaller formats, they look like a good option. And aren't too expensive.

I suppose the remaining question is which would likely be better, a filmstrip projector or an enlarger head? Hmm. I suppose I can just try both.

...

No, i just wanted to make clear that i don`t have experience with them and cannot guide you into the right direction.
As far as i have noticed some of them were cheap. There were exposed and developed film strips you could buy, having pictures and texts of fairy tales - for kids. So some of these film strip projectors will have toy-quality.
But i think there also were film strips for educational purposes, so there also should be better film strip projectors.

The film strip projector will be for 35mm only/the most. You cannot put in a bigger film format and a smaller format... well should be possible but depending on the construction it may be hard to put a 16mm strip in or get it out again... also the question was if the strip projector does have glass plates for film flatness or whether the gate is glassless... then 35mm stripes would work but 16mm stripes may curl too much making it hard to project them sharp.

This would not happen with an enlarger (if it has glass carriers), you could project bigger sizes, but you had to tinker to get a swing head for horizontal and vertical images, to adapt a faster lens to project bigger... and it was bigger and heavier overall.
I`d get a good film-strip projector first, as this was less worksome for being able to project - and if this does not suffice i`d convert an enlarger into a projector. A film-strip projector also was much more portable than a converted enlarger, so if you wanted to project some slides elsewhere you needed one anyway.

...


The destructive aspect never sat well with me. Especially as I've massacred a cut between frames a handful of times when cutting strips to put in sleeves. Even after getting a film slicer to use instead of a scissor, I still occasionally get one that the slicer doesn't cut through and damages the emulsion at the end of the cut.


Consider yourself lucky that you weren't part of the group who had no clue how to spell it and thought it began with a W!

I see... with me it`s rather the opposite. "Slide film is meant to be cut" and i didn`t have problems with ordinary household scissors... i may be in for a "clean projection". Never needed/had a slicer.

Yes, i got the letters right, but the sequence... did produce a funny image of an old-fashioned waiter...

 

[Mr Bill]

I suppose that's good in my case, as when I went to buy a fresnel lens on ebay, a seller sold them in pairs so I have two.

Hi, I'm guessing that you have not been successful with your projector yet. If not, can you give me an approximate focal length of one of your Fresnels? I can probably give you a rough layout to experiment with. Also, what are you planning for a light source? (Need to know, optically, where the light appears to be coming from.)

 

[Crysist]

Hi, I'm guessing that you have not been successful with your projector yet. If not, can you give me an approximate focal length of one of your Fresnels? I can probably give you a rough layout to experiment with. Also, what are you planning for a light source? (Need to know, optically, where the light appears to be coming from.)

I put it aside for a bit. I need to see whether I can source an enlarger head locally or not. Otherwise I'd buy something on ebay. As you said, I'm gonna start with a filmstrip projector and look into whether I'd need an enlarger later on.

I got these Fresnels, one is a 185mm and the other is 120mm. I'm not sure if they'll be a part of my final version, but I had originally gotten them to see what I could use them for with my CS-Lite.

If you use an enlarger you only can project vertical format, if you have 35mm film strips. In theory you could built a different column, which has a 90° angle at the top end, then you had the head in a position to project on the wall and you could swing the head for vertical and horizontal images on the strip.

With these S8 cameras it is not about assessing the (technical) quality of a lens, but to have a less distracting image in the viewfinder. If the viewfinder did have a ground glass the grain of the glass would distract to some extend - that`s probably why many S8 cameras have an aerial image only.

That makes sense, you'd need a very very finely-ground GG otherwise. I wasn't saying it'd be used for the purpose of assessing quality in this case, I was just noting it because that was interesting.

S8 cameras often don`t have tiny lenses. Quite some have lenses that are longer than a 50mm lens for 35mm still.
I don`t know how to test lenses for quality other than doing test shots - i just wanted to point out that an aerial image probably won`t help you ahead. Especially when light is low the image in the viewfinder of a S8 camera looks better than what you capture on the film.

Eh, I guess 8mm is besides the point. But it really does show a lot compared to a GG or test shots! I've seen others put macro lenses or microscope objectives up to the image plane of lenses and are able to measure performance far better than just regular test shots.

Hm... it looks to me that there is some sort of Fresnel lens on the light of you phone. If you shine this through a camera lens it probably will interact optically and may give you a different enlarging (factor) than a negative or slide.

On the other hand if you can make 0.06mm to about 1 cm you`re having quite an enlargement factor there.

When you projected the scale, did you get about the same enlargement of the divisions on the wall like 5mm or 1cm?

So the slide is a fair bit smaller in detail at 0.01mm per division, and with the ticks being quite a bit thinner, and honestly seems at the limits of my old Sonnar lens. Even though not able to focus the scale so sharply, the divisions seem to be on the order of individual mm when thrown up against my wall. Hard to say if a bit less or a bit more than 1mm. But that gives an idea of the magnitude of increase.

Yes, but lenses usually concentrate light at the focal point. That`s why you still get an image on your film up to the edges when the aperture is stopped down.
But my point rather is that lenses also can suffer heat damage. Someone once told me that there were problems when a light head for 4x5 cameras was offered - to convert the 4x5 camera into an enlarger. They used the taking lens on the camera, but the light head apparently produced enough heat to somewhat damage the (taking) lens.
Also cameras on display, close to a window with the sun shining into the lenses for hours every day can suffer lens damage. This of course does take a while and may not apply to every lens, but if you use a laser to point only at a section of the lens you may introduce too much heat/energy onto that spot of the lens and damage the coating or even the glass.
And as you point the laser on lenses some of which will concentrate the laser beam even more... i got a bad feeling about that.

Good thing I'm more focused on the other methods now!

No, i just wanted to make clear that i don`t have experience with them and cannot guide you into the right direction.

As far as i have noticed some of them were cheap. There were exposed and developed film strips you could buy, having pictures and texts of fairy tales - for kids. So some of these film strip projectors will have toy-quality.
But i think there also were film strips for educational purposes, so there also should be better film strip projectors.

Ah, gotcha.

Yes, some do seem like that, but many that come up actually seem for "serious" slide projection.

The film strip projector will be for 35mm only/the most. You cannot put in a bigger film format and a smaller format... well should be possible but depending on the construction it may be hard to put a 16mm strip in or get it out again... also the question was if the strip projector does have glass plates for film flatness or whether the gate is glassless... then 35mm stripes would work but 16mm stripes may curl too much making it hard to project them sharp.

This would not happen with an enlarger (if it has glass carriers), you could project bigger sizes, but you had to tinker to get a swing head for horizontal and vertical images, to adapt a faster lens to project bigger... and it was bigger and heavier overall.
I`d get a good film-strip projector first, as this was less worksome for being able to project - and if this does not suffice i`d convert an enlarger into a projector. A film-strip projector also was much more portable than a converted enlarger, so if you wanted to project some slides elsewhere you needed one anyway.

That seems like a good idea. Yeah, the ability to use glass carrier would be very helpful for smaller formats. But starting with a film-strip projector seems like a better first step for the reason you gave.

Also, some of what I read about enlarging lenses vs projector lenses is that enlarger lenses are more suited for closeup work, while a projector can do farther distances and retain quality. I might get one of those special projector lenses like the Leica Colorplan if I get to a stage of being really into it and wanting to assess quality.

I see... with me it`s rather the opposite. "Slide film is meant to be cut" and i didn`t have problems with ordinary household scissors... i may be in for a "clean projection". Never needed/had a slicer.

I don't see myself as uncoordinated, as I can do some very fine stuff. Yet for some reason, scissors on film I'm BAD at. I have a similar issue slicing bread. I put the blade a set distance from the end, start cutting, and the slice is thicker than I expected. And yes I'm looking at where it meets the bread.

 

[MattKing]

I don't see myself as uncoordinated, as I can do some very fine stuff. Yet for some reason, scissors on film I'm BAD at. I have a similar issue slicing bread. I put the blade a set distance from the end, start cutting, and the slice is thicker than I expected. And yes I'm looking at where it meets the bread.

Turn the bread upside down on the cutting board, press down, and then cut.
Photrio is a great resource, isn't it

 

[Harry Callahan]

...

I got these Fresnels, one is a 185mm and the other is 120mm. I'm not sure if they'll be a part of my final version, but I had originally gotten them to see what I could use them for with my CS-Lite.


That makes sense, you'd need a very very finely-ground GG otherwise. I wasn't saying it'd be used for the purpose of assessing quality in this case, I was just noting it because that was interesting.

...

Well Fresnels... i`ll come back to that later in response to your findings - apart from that you could try to use such a Fresnel to concentrate the light onto the test slide in the camera, but i`m not sure whether it would work that well. I`d start with a smaller light source than a light-panel.

I... don`t really get what you meant then about the S8-cameras... all i could add was that ground glasses have technical limits. The finer you grind a ground glass the finer the grain gets but the less light the glass will collect. The image on the glass gets darker the finer you grind it... but this does not seem to be the point here anyway.

...


Eh, I guess 8mm is besides the point. But it really does show a lot compared to a GG or test shots! I've seen others put macro lenses or microscope objectives up to the image plane of lenses and are able to measure performance far better than just regular test shots.


So the slide is a fair bit smaller in detail at 0.01mm per division, and with the ticks being quite a bit thinner, and honestly seems at the limits of my old Sonnar lens. Even though not able to focus the scale so sharply, the divisions seem to be on the order of individual mm when thrown up against my wall. Hard to say if a bit less or a bit more than 1mm. But that gives an idea of the magnitude of increase.
...

So they use the aerial image of the taking lens to asses its quality... interesting. On the other hand how can you judge lens quality better than by doing test shots? A test shot shows how this very lens will act under this very light situation with this very film (and developer)... ain`t an aerial image test more like an academic test?

Ha! That`s what i assumed. As the light of your phone seems to have a Fresnel lens above the LED, this Fresnel lens probably will interact with the camera lens you`re trying to test. The patter of the Fresnel lens on your phone probably got projected bigger onto the wall, because the pattern acts like a (magnifying) lens itself.
If you project the glass microscope scale you have no interaction - so this is how a test slide inside the camera would be projected to the wall.
I am not trying to laugh at you, i`m just trying to explain why i said in the beginning that projection-testing a camera lens should be difficult.
Now you had to project the microscope scale as sharp as possible onto the wall - should be difficult because the scale and the camera lens should be entirely stationary - and then you had to judge whether the 1/100m pattern is tack sharp, sharp, slightly blurred or blurred but still recognizable.
Tack sharp did mean that your lens does resolve over 100ll/mm, sharp did mean about 100ll/mm, slightly blurred did mean a little less than 100ll/mm and blurred but recognizable did mean, well, maybe 85ll/mm.
To get this as sharp as possible you had to turn the focusing ring of the lens (assuming you test lens-on-camera) down to a fraction of a mm, to judge sharpness you had to move your eyes closer to the wall so the camera had to be on a tripod or alike...
...that's why i said in the beginning it should be difficult.

...

Good thing I'm more focused on the other methods now!


Ah, gotcha.

Yes, some do seem like that, but many that come up actually seem for "serious" slide projection.


That seems like a good idea. Yeah, the ability to use glass carrier would be very helpful for smaller formats. But starting with a film-strip projector seems like a better first step for the reason you gave.

...

Also i am no expert on lasers, maybe there is a way but... you had to dive into this and lens damage by heat/light shining into the lens is a thing.

Surely there will be some good film-strip projectors, but as said i `m not into these, the only thing i am aware is that some were meant for kids. You probably will be able to judge quality of the projector by the lens attached. On toy projectors lenses often don`t have any engraving at all or just a name, no focal length etc. .

I also meant to look for a film-strip projector having a glass gate. I am pretty sure i once seen one, such a projector would enable you to project smaller formats too.

...

Also, some of what I read about enlarging lenses vs projector lenses is that enlarger lenses are more suited for closeup work, while a projector can do farther distances and retain quality. I might get one of those special projector lenses like the Leica Colorplan if I get to a stage of being really into it and wanting to assess quality.


I don't see myself as uncoordinated, as I can do some very fine stuff. Yet for some reason, scissors on film I'm BAD at. I have a similar issue slicing bread. I put the blade a set distance from the end, start cutting, and the slice is thicker than I expected. And yes I'm looking at where it meets the bread.

Yes, enlarging lenses are optimized for close range as the enlarging paper is pretty close to the head - but the better lenses also work on greater distances as you can use them for big enlargements. In the end it does depend on how big you want to project. If you wanted to project in a cinema hall where the projector is like 50ft away from the screen, yes then a "real" projection lens may be suitable - but if you project a few feet onto your wall at home a good enlarging lens should do the trick.

Hm, strange... maybe you`re better at merging things than at separating. I mean when i cut bread i also sometimes miss a slice, but cutting slides...
Anyway, film-strips also have advantages. They need way less space than mounted slides in magazines. A film-strip projector basically has no moving parts that could jam or wear out. And mounting 36 slides into frames... i can do that for an hour or two but then... i need a break!

 

[Crysist]

Well Fresnels... i`ll come back to that later in response to your findings - apart from that you could try to use such a Fresnel to concentrate the light onto the test slide in the camera, but i`m not sure whether it would work that well. I`d start with a smaller light source than a light-panel.

I... don`t really get what you meant then about the S8-cameras... all i could add was that ground glasses have technical limits. The finer you grind a ground glass the finer the grain gets but the less light the glass will collect. The image on the glass gets darker the finer you grind it... but this does not seem to be the point here anyway.

Yeah, I was really just commenting on it lol. I feel bad when people make an exhaustive reply and I skip parts of it!

So they use the aerial image of the taking lens to asses its quality... interesting. On the other hand how can you judge lens quality better than by doing test shots? A test shot shows how this very lens will act under this very light situation with this very film (and developer)... ain`t an aerial image test more like an academic test?

Yes, but you're able to isolate the film a lot more in such a test. This is usually used non-photographically, but you could also just use it to photograph the image formed by a lens.

Ha! That`s what i assumed. As the light of your phone seems to have a Fresnel lens above the LED, this Fresnel lens probably will interact with the camera lens you`re trying to test. The patter of the Fresnel lens on your phone probably got projected bigger onto the wall, because the pattern acts like a (magnifying) lens itself.
If you project the glass microscope scale you have no interaction - so this is how a test slide inside the camera would be projected to the wall.
I am not trying to laugh at you, i`m just trying to explain why i said in the beginning that projection-testing a camera lens should be difficult.

Heh, none taken, but I think you misunderstood what difficulty I was describing. This lens is 90 years old, I don't expect it to resolve 200lp/mm wide open. Despite it being a very well-regarded lens.

And your figuring with the fresnel doesn't seem right. Regardless of what way the light is converged/diverged by the fresnel pattern, I place the light at the focal point of the lens. Remember, I am not measuring the width of the light, I am measuring the image of the fresnel pattern itself. The fresnel wouldn't have an effect after the light has gone through it. If you look at the light, that fresnel still is 4mm wide, it didn't change size when the light was turned on.

Also, an online calculator says a 50mm focal length at 2m would produce 0.026x magnification on the film plane. Thus, going in the opposite direction, that's nearly a 40x magnification.

Now you had to project the microscope scale as sharp as possible onto the wall - should be difficult because the scale and the camera lens should be entirely stationary - and then you had to judge whether the 1/100m pattern is tack sharp, sharp, slightly blurred or blurred but still recognizable.
Tack sharp did mean that your lens does resolve over 100ll/mm, sharp did mean about 100ll/mm, slightly blurred did mean a little less than 100ll/mm and blurred but recognizable did mean, well, maybe 85ll/mm.
To get this as sharp as possible you had to turn the focusing ring of the lens (assuming you test lens-on-camera) down to a fraction of a mm, to judge sharpness you had to move your eyes closer to the wall so the camera had to be on a tripod or alike...
...that's why i said in the beginning it should be difficult.

It certainly isn't the best for determining sharpness at that scale difference, but you might be overestimating how hard it is to hold these together. It's not fun or easy, but I just put a rubber band on my phone to hold the slide over the flashlight, then just aligned it to the focal plane of the lens. You can make a very shallow leveraging motion between the lens and the slide to get the right distance. It's not hard to hold things that small and light still within under 1mm, especially if they're resting against something else.

Also i am no expert on lasers, maybe there is a way but... you had to dive into this and lens damage by heat/light shining into the lens is a thing.

Surely there will be some good film-strip projectors, but as said i `m not into these, the only thing i am aware is that some were meant for kids. You probably will be able to judge quality of the projector by the lens attached. On toy projectors lenses often don`t have any engraving at all or just a name, no focal length etc. .

I also meant to look for a film-strip projector having a glass gate. I am pretty sure i once seen one, such a projector would enable you to project smaller formats too.

So one common one that shows up a lot are these Dukane projectors in multiple form-factors. They have plastic loops to hold filmstrips and they have metal apertures with glass gates. The only odd thing is they have these rather strict warnings about using specific 300W bulbs. I still wouldn't mind trying to play around with it to use more available bulbs, if needed.

Also, if it's any context, one of these is what I was imagining "making" at the start of this thread: https://elevanfilm.com/product/elevanfilm-mini-projector-4-0/

Compared to the fears of how well it works, I see some images of some guy using it to project IMAX filmstrips. The site says it uses a "150W equivalent 365nm" bulb, whatever that means. I guess it's a lower wattage LED but comparable to an incandescent 150W bulb used in a slide projector? I know LED bulbs can run on far fewer watts and produce as bright of light.

Yes, enlarging lenses are optimized for close range as the enlarging paper is pretty close to the head - but the better lenses also work on greater distances as you can use them for big enlargements. In the end it does depend on how big you want to project. If you wanted to project in a cinema hall where the projector is like 50ft away from the screen, yes then a "real" projection lens may be suitable - but if you project a few feet onto your wall at home a good enlarging lens should do the trick.

Ah, that's good! No, I don't expect to project on a 50ft screen anytime soon. And that'd need a VERY powerful light, no?? But if I learn something from that other thread I made about increasing the density of slides beyond what they're usually capable of, I might be able to rival the contrast ratios only possible with OLEDs! That'd need a good light!

Hm, strange... maybe you`re better at merging things than at separating. I mean when i cut bread i also sometimes miss a slice, but cutting slides...
Anyway, film-strips also have advantages. They need way less space than mounted slides in magazines. A film-strip projector basically has no moving parts that could jam or wear out. And mounting 36 slides into frames... i can do that for an hour or two but then... i need a break!

Slides and slices are too difficult for me, it figures they're named so similarly!

I respect that kind of dedication, there are very repetitive things I enjoy.. or don't mind doing for an hour or so. Mounting slides seems like I'd be doomed to fail!

Turn the bread upside down on the cutting board, press down, and then cut.
Photrio is a great resource, isn't it

It really is! I salute you and @koraks for being so helpful, even in the culinary arts!

I should give back there. Did you know you can use a peeler backwards and forwards so you don't need to lift it between passes? Move a zester over a lemon/lime while rotating it to avoid doing just many tiny patches?? Get eggs to room temperature in water?? And frozen meat too!!

 

[Harry Callahan]

Yeah, I was really just commenting on it lol. I feel bad when people make an exhaustive reply and I skip parts of it!


Yes, but you're able to isolate the film a lot more in such a test. This is usually used non-photographically, but you could also just use it to photograph the image formed by a lens.


...

Oh i also feel bad, so... lol.

I mean that an aerial image will show you how good the photograph would be if there was a film that is as good as your eye. I see that an aerial image test does make some sense, but i don`t see what sense it does in "real life photography" - but anyway.

...

Heh, none taken, but I think you misunderstood what difficulty I was describing. This lens is 90 years old, I don't expect it to resolve 200lp/mm wide open. Despite it being a very well-regarded lens.

And your figuring with the fresnel doesn't seem right. Regardless of what way the light is converged/diverged by the fresnel pattern, I place the light at the focal point of the lens. Remember, I am not measuring the width of the light, I am measuring the image of the fresnel pattern itself. The fresnel wouldn't have an effect after the light has gone through it. If you look at the light, that fresnel still is 4mm wide, it didn't change size when the light was turned on.

Also, an online calculator says a 50mm focal length at 2m would produce 0.026x magnification on the film plane. Thus, going in the opposite direction, that's nearly a 40x magnification.


...

Ah, good. Also i assumed the lens to be newer, f1.5 sounded like pretty new. Is this lens for 35mm still or a smaller format?

Well you said that when projecting the Fresnel pattern of your phone light you get a pattern on the wall being 5mm or 1cm wide (depending on what distance there is to the wall), while the pattern of the Fresnel lens itself is about 0.06mm... ah and the microscope scale is 0.01mm so they are smaller. Yes, then i got this wrong.
On the other hand if you wanted to projection test lenses you needed a tight pattern making it harder to judge when projected to a wall.

...


It certainly isn't the best for determining sharpness at that scale difference, but you might be overestimating how hard it is to hold these together. It's not fun or easy, but I just put a rubber band on my phone to hold the slide over the flashlight, then just aligned it to the focal plane of the lens. You can make a very shallow leveraging motion between the lens and the slide to get the right distance. It's not hard to hold things that small and light still within under 1mm, especially if they're resting against something else.


...

Well, as i don`t have a microscope, i sometimes look at a negative with a strong magnifying glass - and when it gets to 1/100mm it is so hard to hold this still enough so i can see anything. I decided to lay the negative onto a light source and rest my arm holding the lens on the table and still it is hard to judge the sharpness of the neg - so when projecting 1/100mm to a wall i cannot imagine this to be a lot more steady.
You say holding it still under 1mm - yes that`s possible, but if you want to judge if that 1/100mm on the neg is sharp on the wall you need to hold this still down to 1/100mm; otherwise you may mistake shake for blur.

...

So one common one that shows up a lot are these Dukane projectors in multiple form-factors. They have plastic loops to hold filmstrips and they have metal apertures with glass gates. The only odd thing is they have these rather strict warnings about using specific 300W bulbs. I still wouldn't mind trying to play around with it to use more available bulbs, if needed.

Also, if it's any context, one of these is what I was imagining "making" at the start of this thread: https://elevanfilm.com/product/elevanfilm-mini-projector-4-0/

Compared to the fears of how well it works, I see some images of some guy using it to project IMAX filmstrips. The site says it uses a "150W equivalent 365nm" bulb, whatever that means. I guess it's a lower wattage LED but comparable to an incandescent 150W bulb used in a slide projector? I know LED bulbs can run on far fewer watts and produce as bright of light.


...

These Dukanes look pretty "new" - 70s i`d say, i think i`ve only seen film-strip projectors from the 50s and 40s. Glass gates are good for flatness and should help on smaller formats, but the strip moving through the projector vertical does indicate that these projectors are not for full frame (24mmx36mm) but only half frame (18mmx24mm) and therefore cannot project ordinary 35mm slides. Even if, you only could project vertical format as the head cannot be rotated...
unless you lay it on the side to project horizontal, but it doesn`t look like it can/should be layed on the side.
I think i`ve seen a film-strip projector where the film moved horizontally through the projector - or it was a film-strip-attachment for an ordinary slide projector.
This link is of a Dukane 500 using 500W bulbs and no warnings about special bulbs... but playing around may be needed anyway as some projector bulbs no longer are made. LEDs are an option, if there is enough space inside the housing (what it usually is), they also have the advantage of producing fewer heat so the slide film itself can benefit from a modern light source, too.
The "elevanfilm" link doesn`t load, so i cannot take a look at this projector. "365nm" sounds like 365 nanometer, which should be a special spectral color - should be blue. It could mean "cold white" light, which would make sense.
A 30W LED should have about the same light output as a 150W bulb.

...

Ah, that's good! No, I don't expect to project on a 50ft screen anytime soon. And that'd need a VERY powerful light, no?? But if I learn something from that other thread I made about increasing the density of slides beyond what they're usually capable of, I might be able to rival the contrast ratios only possible with OLEDs! That'd need a good light!


Slides and slices are too difficult for me, it figures they're named so similarly!

I respect that kind of dedication, there are very repetitive things I enjoy.. or don't mind doing for an hour or so. Mounting slides seems like I'd be doomed to fail!


...

Well, you also could use a long focal length to project a rather small image on a screen being 50ft away, but if you wanted to fill such a screen, yes, then you needed a little more light...

Good there is sliced bread - and at least some years ago you could have your slides mounted... but bread is more important... i think.

 

[Crysist]

Oh i also feel bad, so... lol.

I mean that an aerial image will show you how good the photograph would be if there was a film that is as good as your eye. I see that an aerial image test does make some sense, but i don`t see what sense it does in "real life photography" - but anyway.

Yeah it's more of a scientific measurement. But it's the same mechanism by which microscopes work soooo... yeah! I seem people attach microscope objective lenses to their cameras via another lens focused on its focal point.

Ah, good. Also i assumed the lens to be newer, f1.5 sounded like pretty new. Is this lens for 35mm still or a smaller format?

Well you said that when projecting the Fresnel pattern of your phone light you get a pattern on the wall being 5mm or 1cm wide (depending on what distance there is to the wall), while the pattern of the Fresnel lens itself is about 0.06mm... ah and the microscope scale is 0.01mm so they are smaller. Yes, then i got this wrong.
On the other hand if you wanted to projection test lenses you needed a tight pattern making it harder to judge when projected to a wall.

It's a Contax Zeiss 50mm/1.5 from 1932, mine is from 37. It is quite sharp in the center for such a fast lens.... and for the time. But it does lose quite a large bit of contrast wide open and suffers some spherical aberration.

No worries, I've gotten confused reading the scale on this thing too many times.

Well, as i don`t have a microscope, i sometimes look at a negative with a strong magnifying glass - and when it gets to 1/100mm it is so hard to hold this still enough so i can see anything. I decided to lay the negative onto a light source and rest my arm holding the lens on the table and still it is hard to judge the sharpness of the neg - so when projecting 1/100mm to a wall i cannot imagine this to be a lot more steady.
You say holding it still under 1mm - yes that`s possible, but if you want to judge if that 1/100mm on the neg is sharp on the wall you need to hold this still down to 1/100mm; otherwise you may mistake shake for blur.

Ah, right, no I have loupes for all that! I even got this 75x Peak Stand Microscope to use as it combines the worst features of both: a small, inverted image and a plastic part you need to press against the sample!

Ok, I mean I wanted a microscope that wasn't gigantic, just the optics! Basically a "super loupe", and that fit my needs! I tried a few cheap ones from amazon and they were either marked higher magnification than they actually were, or too low quality.

These Dukanes look pretty "new" - 70s i`d say, i think i`ve only seen film-strip projectors from the 50s and 40s. Glass gates are good for flatness and should help on smaller formats, but the strip moving through the projector vertical does indicate that these projectors are not for full frame (24mmx36mm) but only half frame (18mmx24mm) and therefore cannot project ordinary 35mm slides. Even if, you only could project vertical format as the head cannot be rotated...
unless you lay it on the side to project horizontal, but it doesn`t look like it can/should be layed on the side.
I think i`ve seen a film-strip projector where the film moved horizontally through the projector - or it was a film-strip-attachment for an ordinary slide projector.
This link is of a Dukane 500 using 500W bulbs and no warnings about special bulbs... but playing around may be needed anyway as some projector bulbs no longer are made. LEDs are an option, if there is enough space inside the housing (what it usually is), they also have the advantage of producing fewer heat so the slide film itself can benefit from a modern light source, too.
The "elevanfilm" link doesn`t load, so i cannot take a look at this projector. "365nm" sounds like 365 nanometer, which should be a special spectral color - should be blue. It could mean "cold white" light, which would make sense.
A 30W LED should have about the same light output as a 150W bulb.

Well.... I have shot mostly half-frame in the past 8 months so no problems there! Well, except that it'd need to be on its side most of the time.

And sorry, there were quite a few and I thought that one was similar. The ones I see all had 300W. Those are the Dukane 300, 28A33, 28A55. You need to take the cover off to see that warning it seems. Here's a video with a timestamp of someone opening one:



Here's a couple of images from the site:

Shows how it mounts to the back of many MF cameras to convert them to a projector.

Well, you also could use a long focal length to project a rather small image on a screen being 50ft away, but if you wanted to fill such a screen, yes, then you needed a little more light...

Lucky me. I'll come back when I do need that kind of juice.

Good there is sliced bread - and at least some years ago you could have your slides mounted... but bread is more important... i think.

I love film but bread has been a staple in my life for far longer! I would have to agree.

 

[jeffreyg]

crysist
I know you are considering a dys projector. I have had this for over fifty years so it might give you some ideas.

 

[Mr Bill]

I got these Fresnels, one is a 185mm and the other is 120mm. I'm not sure if they'll be a part of my final version,...

I understand that you've put off your projector project for the time being. Just in case I'm not around when you possibly resurrect the project...

If you combine your two Fresnels the resulting focal length is gonna be about 70 to 75mm. (Let's say 75 for ease of the math.) There is a general rule for lenses, that to get a same size image, the optical distance between object and image should be about 4 focal lengths (the lens is right in the middle). So in this case 4×75mm = 300mm.

Per my post #5 you want to project an image of your light source into the "pupil" of your projection lens. (I'm presuming it's the 50mm f/1.5 lens you have mentioned.) So, if you arrange a light source, say the filament of a tungsten lamp, about 300mm (~12 inches) from said lens, and place your Fresnel lenses in the middle, you should be able to do this.

Please don't try to hand hold; it'll just lead to frustration. Find a way to prop things up on your kitchen table, perhaps. Maybe a bean bag, or whatever, to hold the projection lens. The Fresnels, maybe tape them between a couple of cereal boxes, or whatever (maybe you have a couple of corn muffin mix boxes). A couple of feet or so in front of the projection lens set up a "projection screen." This could be a sheet of white paper taped to another cereal box, etc. I dunno how you're gonna deal with the lamp, but I'm sure you can find a way.

Observe where the image of lamp is with respect to the projection lens. Move things around until you get this image, the bright spot, into the projection lens.

Now all you're missing is something to project. Instead of film let me suggest something like a black hair comb. (You won't have to worry about dropping and scratching it, etc.) Holding the comb in your hand, move it somewhere between the Fresnels and the projection lens until it comes into focus on the screen. You might have to dim the room somewhat to see it.

Ok, hopefully you did this successfully. If so, now to refine the system. First is the light source (which is horribly inefficient). But now that you have an idea how the setup works perhaps you could try a flashlight (aka torch). Modern LED units typically have their own optical system, so you might have to fiddle around a bit.

If you get something bright enough to work with, then maybe you can build something a little more sophisticated.