Paper negative enlarger prototype

[bergytone]

I have just finished a prototype of a paper negative enlarger. Inspired by member 'blindpig''s version of an opaque projector that he posted last year, I decided to try my hand at making one. Here's what it looks like:

I started with an old Vivitar enlarger (the one I used in high school) and used it's easel and lens holder with bellows. I wanted to be able to enlarge my paper negatives from the 6x6 or 6x9 vintage folders I've been playing with, as contact prints from them lose some sharpness, and are kind of small.

The light sources are made from energy drink cans and pepsi cans carefully cut up. (that energy drink tastes awful by the way) I had to cut the ends out to fit the lamp socket, and cut the other end out so I could get the bulb in and out. The nice thing about aluminum cans is that they are easy to work with, and they can be jammed inside each other for a perfect light tight fit.

I used aluminum sheet to make the 'light box'. The aluminum I used must be some grade of aircraft aluminum, as it was very hard to bend up. There's an upper and a lower section, with the lower section being glued to the bellows from the Vivitar.

I painted the inside black and used automotive grade black silicone to caulk up the joints to make it light tight. The initial tests were very exciting. I am using my Omagar 80mm enlarger lens, which limits the size of the print I can make. It's nice, because it screwed right into where the vivitar 50mm lens was. The negative is placed right onto the top opening, and a piece of glass is used to keep it flat. I was impressed that with a piece of white paper in the opening, the resulting projected image was pretty evenly white.

I put a text doc on the top with fine print (the back of the Ilford Multigrade filter box) and enlarged it to 8x10 size and I could see the letters were sharp and crisp. Putting some paper negatives up there projected them beautifully, and I think this is going to produce nice prints. Contrast of the image seemed normal.

Can't wait to see how it works... the proof's in the printing

 

[Joe VanCleave]

This is very interesting. I've also been wanting to make one of these.

I'd be interested to hear around how you prevent glare and hot-spots on the shiny, glossy negatives, that would show up on the prints.

Very interested in seeing your resulting prints.

~Joe

 

[NedL]

very cool! I hope it works well and look forward to seeing some prints!

 

[AgX]

Enough "power to win".

 

[AgX]

Once there was a commercial enlarger that allowed either to use a paper- or a film-negative.

 

[bergytone]

Joe, I just tried something. I put a mirror on the top, where the negative would go. I saw a small amount of flaring near the sides, but otherwise it showed up dark. The flaring was due to my 'reflector' on the lower edge of the light tubes. I put a couple pieces of black felt down on them and almost all the flaring went away...
here's the reflector I was talking about:

The only thing I see that is a distortion is that the side edges show a small shadow... due to the thickness of the aluminum plate. But that can be cropped out.

Here's a question to you and earlj.... the bulbs I'm using are the 'daylight' florescent CFL. Will these have too much blue light for printing on MGiV? Will I be better with the 'soft white' bulbs, as they have a color temperature closer to tungsten?

 

[bergytone]

agx... enough power to win... you saw that! there's enough caffeine drank in the making of this to develop three rolls of Tri-x

 

[Joe VanCleave]

...Here's a question to you and earlj.... the bulbs I'm using are the 'daylight' florescent CFL. Will these have too much blue light for printing on MGiV? Will I be better with the 'soft white' bulbs, as they have a color temperature closer to tungsten?

I don't have any direct experience in printing with either of those light sources, so you're best to experiment a bit with both kinds.

~Joe

 

[SMBooth]

So let me get this right, the light is reflecting off the paper negative instead of through the traditional negative. Hmmm, can i get a image from the front showing the light mounted?

 

[bergytone]

Shane, the light is reflecting off the negative, or whatever you put up on the top. I can put my hand up there and I get a perfect image (in color) of my hand on the easel. The concept of reflected light casting an image is a little hard to grasp, but your scanner does that when you scan in the reflective mode. It has a light that travels down the platen and the sensor just picks up the reflected light and dark areas reflected off the paper. I'll try to get a front view image up tomorrow.

I did a few quick tests with the enlarger tonight. Didn't have a lot of time, but I ran some test strips through. I am seeing slightly more light at the edges, meaning the illumination isn't uniform. One of the problems I have is that I don't have any really sharp paper negatives just yet. I'm still learning exposure times with the paper negatives and It's hard to get outside shots right now with snow all over, and sunny days just produce blown out paper negatives. I have a bunch of pinhole paper negs, but as we all know, they are a bit soft.

If someone wants to send me a nice, sharp 6x9 paper negative with good tone, that will save me some time. PM me if that's something that you can help me with.

 

[SMBooth]

Thanks for that. I'm in Australia but happy to send you some step wedges if you wish. May take a while getting there.

 

[NedL]

My enlarger has a fluorescent light that is extremely blue. I usually do split grade printing with a green filter and a deep blue (47B) filter, and it works great. I read that normal multigrade filters might not work well with my light ( the steps not evenly spaced, with some of the steps being too large and some not doing much at all ). So, if the light is really blue, you could try reading about split grade printing and doing part of the exposure with a green filter.

 

[AgX]

Once there was a commercial enlarger that allowed either to use a paper- or a film-negative.

... by switching from reflective to transmissive lighting.

 

[bergytone]

One thing I don't like about these CFL florescents is that they have that warm up time before they reach full brightness. To get consistent results I'll have to let them warm up good with the lens cap on. then quickly get the print going before they cool down. I may try some incandescents, but heat will be a real problem.

 

[NedL]

I hold a black card under the lens for 30 seconds, then use it to time the print as well, with a metronome. That might work. Actually, my card is black underneath and white on top.

 

[bergytone]

I was experimenting last night with trying to make the image cast on the easel even. When I put a white piece of paper on the negative opening, I get a pretty even white light image. I used my Ilford exposure meter to measure the light levels from edge to edge and with the lens open all the way, the image was very close to even. Within a couple of small graduations on the meter. But when I stopped the lens down, I could plainly see a darker spot in the middle of the image, like a 'reverse vignetting'. For each increase in lens stop I could see the darker spot in the center grow larger. I used the Ilford meter and could see that there was now 10 to 12 divisions of difference edge to edge.

Can anyone explain why stopping the lens down effectively creates a darker center image? Being that this enlarger arrangement has no 'condenser' for the light, maybe that has something to do with it. I can probably do my exposures with the lens wide open, maybe I'll have to just get lower wattage bulbs to give reasonable exposure times. Focusing will be much more critical too.

Does anyone have any thoughts on how I can stop down the light without 'reverse vignetting'?

 

[AgX]

The less point-like the light source is, the less effect a condenser will have. Thus the lack of a condenser could not be the reason behind that dark spot.

Is that spot actually circular?

 

[bergytone]

Yes...very circular

 

[blindpig]

Sorry about being slow to respond but have been away for a while and am just now catching up.
From my experience with the reflective enlarger there hasn't been a reflective problem causing uneven or hot spots in the illumination.I suspect that the light inside the head is getting to the lens without bouncing off the negative,try shielding the lens from direct light.Another problem could be the closeness of the lens to the negative( if you recall I mentioned that you might need a 150mm or longer lens to allow proper light angles for the area being copied). It could be necessary to forgo the glass in your negative carrier as the circle you are seeing that gets sharper when stopping down is probably the lens it'self reflecting off the glass(which would be made easier with non image forming light striking it)
Having trouble with computer so will send this and try to add more later.
Don.

 

[blindpig]

Back,hope" puter "will behave.
Eric the reason for the distance from the lens to negative in my enlarger is to allow for proper light coverage needed to copy the reflective original(actually this is a small copy camera layout). The ideal would be for the center of the light sources be aimed toward the opposite edge of the original being copied so the center would be illuminated by the falloff from the center of the light beams. The optimum angle for this light path would be 45 degrees to prevent reflections at 90 degrees,which the lens is using.I'm attaching a crude drawing showing this setup.



As you can see the lens is protected from direct light and so is unused areas in the box.Hope this helps some.
Don

 

[Andrew O'Neill]

This is so cool. I passed it on to a colleague of mine who teaches high school film photography. Thank you!

 

[Bob Carnie]

I knew Don (blindpig) in a previous life, when I was doing photcomp and we were both using a very unique camera system..


I know his capabilities... so for the uninformed . ME. what are the advantages of a paper negative enlargers???

 

[Andrew O'Neill]

The main advantage is that you can make an enlarged print from a paper negative without having to print through its paper fibres. Probably a bright projected image for faster printing… I really would like to see a print, say up to 16x20!

 

[blindpig]

Hey Bob,
Andrew is right about enlarging without the paper texture showing.You might consider it a copy camera set up because basically that's what it is.
As for making clear enlargements it will depend on the lens and lighting setup.
Andrew you might consider that all color separations for offset and lithographic printing were made with copy cameras before scanners came along and were capable of sharp enlargements as well as reductions.I'm not claiming my little prototype is capable of what those precise instruments were but the idea is the same so !6X20 prints aren't out of the question,IMHO.
Eric keep on working with your set up and you will be surprised at the results......
Don

 

[bergytone]

As an update, I ran some tests the other night. I first needed some good paper negatives to start with, so I shot a series of pictures of my Jeep in the snowy driveway... I figured since the jeep is kind of slate colored it was like a giant grey card. This was also an interesting way to shoot paper negatives. I cut up a strip of paper about 30" long and 1.1 inches wide and rolled it into a re-usable 35mm fim can. I put it in the Nikon FM and shot some bracketed exposures. Same subject, repeated with various F stops so I could get a range of negative densities. I used ilford MGiV pre-flashed.

The resulting negatives turned out good. I could see a some sharp detail, but the highlights were still a little blown out. Obviously too small to contact print. So I made a 35mm sized mask for my new enlarger, and ran a test print at 4x6" size. Here's my result: (click on it to make it bigger)



The print is very contrasty, and was also printed on Ilford MGiv paper. There is a notable lack of detail in the shadow areas, and a scan of the negative shows this. (look at the rear window reflections) :

An examination of the projected image on the easel shows that these details are there, I just lost them in the printing. It is not at all an effect of my enlarger. Being that I have no means of putting a multigrade filter over the two light sources, I may have to resort to graded paper to get the contrast in line. Unless someone wants to give me some larger sized pieces of filter gel that I could put in the lamp housings. I wish I had one of you guys that have been printing for many years in the darkroom with me to help with taming the contrast shrew.

Here's a shot of the negative next to the enlargement to show the degree of enlargement, and the paper negative strip technique. That's a story in itself, how to advance the paper negative without sprockets. Keep in mind, this is the first pass at this... hopefully it will get better as I learn how to print with this contraption.