Shutter mechanisms for pinhole

[OAPOli]

Here is the shutter on the Holga 120 WPC. Push to open.

 

[cliveh]

Well my zen pinhole camera uses magnets within the wood to hold the shutter open and closed:-

How simple can a camera be? - AlternativePhotography.com

No camera is simpler than the Zen Pinhole Camera according to Clive Heritage-Tilley. This is just about how simple a camera can get.

www.alternativephotography.com

 

[Aaalbores]

For my large format cameras I have an old Compur shutter that only does B. I have a Lennox Laser pinhole mounted in it using a Copal #0 mount. The unit is in a Wista-type lensboard. At 0.3mm the pinhole is a bit of a compromise to cover the possible formats (roll-film to 8x10)

There's a design for a 3D printed shutter on Thingiverse which I used on my WillTravel pinhole camera. You can see it in action at http://dotinthelandscape.org/three_d_printing/willtravel_3d_printed_cameras/ and a little movie at http://dotinthelandscape.org/three_...rinted_cameras/images/pinholeshuttermovie.mp4

To use something like this your filter mount would have to be secured to less than the full circle to let the shutter swing out of the way.

If the camera is going to be wide, you need to think about what might be in the line of sight. I had to thin the shutter blade on the WillTravel version to get the edge out of frame, and that has a pinhole to film distance of around 58mm. The camera can do 4x5 or roll-film formats. Putting a front filter on may require a much larger filter diameter than you expect.

You can always draw this out - a right angled triangle will give you half the format diagonal and the film to pinhole distance, then you project the hypotenuse through the pinhole location to see what clearance you will get, assuming the front of the camera is parallel to the film plane. I like to reduce the error part in my 'trial and error' approach!

Thanks for your comment. The 3D printed shutter you showed is closer to the idea that i had in mind, but of course that 3D printed contraption is too big to fit in the front of my camera and behind the filter. I take this as a fun challenge, to make a thin version of that mechanism with household materials. I can even try to hide the mechanism in the interior side.
Of course i have to make sure that i don't block the light. For that i just look through the big hole in the mdf piece from every angle (before installing the pinhole) and make sure that i can see nothing in the way blocking light

 

[Aaalbores]

I don't know where you shop, but around here you can get trashed-out, old, worthless cameras for next to nothing, or the cost of shipping -- whichever is more. See link above for plenty of examples.

The only places where i can shop for film cameras here in Spain (that i'm aware of, i may be missing something...) are second hand stores (whether they are physical or online). Physical second hand stores usually have film cameras in working conditions, but prices are not low (a folder camera in working condition: 90€). Then, second hand apps like Wallapop, there you can find more things, but never found a folder camera for less than 30€ (and then you add the shipping costs). Then there's ebay, but all the interesting things i find there come from Germany, France or UK, and shipping costs are high

 

[grahamp]

My Zeroimage has a nice manual shutter that slides, but also works as a pivot type with a cable release. That's nice for long exposures and means I do not have to risk peering at the front of the camera to see if the shutter is open. I actually got in my own picture by mistake doing this on a wide angle unit.

The elastic band and cable release shutter (see my links previously) on my 4x5/roll-film WillTravel is nice because that's the way I work with a regular 4x5. I can just about do a reliable 1/2 second with manual control of the release, so film ratings in the ISO 200 to 400 range is about viable in N. California. On really bright days I prefer ISO 50 to 100. The pinhole size is basically governed by the format and the depth of the body, and the pinhole size and a shutter open time of 1/2 second or longer dictates the film speed. For such a simple optical system, it has a lot of constraints. Part of the charm, I suppose.

 

[xkaes]

The only places where i can shop for film cameras here in Spain (that i'm aware of, i may be missing something...) are second hand stores (whether they are physical or online).

Around here there are thrift stores, yard / garage / neighborhood / moving sales all the time with people wanting to get rid of stuff ASAP. Most dead cameras end up in the trash. Maybe that's a place to look. All you need is the lens.

 

[Aaalbores]

Here is how the Noon pinhole camera I had dealt with this:
View attachment 361596

In case it isn't clear, the flap pivots on the screw.
Plus the above mentioned "one one-thousand, two one-thousand, three one-thousand,....".
A reasonably good tripod is important as well.

These wooden cameras are gorgeous. But when i see that shutter i just don't like it. Yes, it's a simple and elegant solution, but do they stay closed when you move the camera around?
And why don't pinhole cameras have a second layer of protection? Other cameras have.
In any case, when i knew how much those gorgeous wooden cameras cost, i decided to make my own version

It's not so pretty, i know that, but i made it with my own hands, and it was really fun, and it works like a charm, and it was dirt cheap

 

[MattKing]

But when i see that shutter i just don't like it. Yes, it's a simple and elegant solution, but do they stay closed when you move the camera around?

Yes. There is a fair amount of smooth friction between the shutter and the camera body - smooth because everything is well made, and the velvet/felt behind the "shutter" that moves across the face of the body is high grade.
In addition, I carried it around in a bag. Even if the shutter opens when you don't want it too, with an aperture around f/200, and being inside a bag, a short term problem with light leak is unlikely to cause a problem.
It also helps that the inside of the camera is well blacked.

 

[DWThomas]

@Hassasin, @MattKing sums up the situation well. My term "Angle of View" is perhaps from my use of PinholeDesigner, a Windows app that does all these calculations. There is another, Mr Pinhole, that runs on web script so it's platform independent. That is an advantage, but my experience is that it seems a bit pessimistic and also rather obscures some of the assumptions it makes.

Perhaps I was less than clear in some of my statements, although I think we mostly agree. The film format and angle of view/image circle/whatever establishes the "focal length"/pinhole-to-film distance needed. So then, solve for pinhole diameter. One can start from multiple points to get to a working set of data.

@Bronson Dugnutt brings up the wavelength effects which I decided to leave out in the upthread blather, but is also a valid point. Pinhole Designer defaults to 550nm, a sort of mid-spectrum green. Since the human eye is pretty centered on green and I use Fuji green sensitive X-ray film in my 8x10, that wavelength gets used without thinking about it.

If I'm understanding correctly (always suspect) the camera @Aaalbores shows, as it is configured, would appear to need the shutter mechanics sunk into a round area where there isn't much room for a swiveling blade to get out of the way. If the inner surface of that MDF/Masonite disk could come up to flush with the mount or a bit above, the lever and shutter could swing out beyond the edge of the mount which might help a lot. With the pinhole plate mounted behind that disk, there needs to be a fair amount of clearance around the optical axis when the shutter is open. You may note on my two wooden cameras there is a blackened counterbore on the front surface. (Part of the reason for doing a scale cross-section).

The pivoting flap shutters shown at my pinhole gallery have a cardstock washer under the pivot point, a nylon washer under the screwhead, and two screws serving as limits for open and closed. when all is well, the pivot screw is adjusted so there is a bit of friction that keeps the shutter flap where it's put. That said, my use is with sheet film in holders, so no significant light seal is necessary. In a roll film camera that might be more important. Those flaps were made from .020" matte black anodized aluminum; so with that and the pinhole mounting block flat black, I've not seen a problem.

Anyway, it's for fun -- and three of my 8x10 contact prints made it into a juried show a few years back!

​

 

[xkaes]

The film format and angle of view/image circle/whatever establishes the "focal length"/pinhole-to-film distance needed.

The angle of view and the image circle are normally separate entities with a typical lens. For example, one 100mm lens might have a 150mm IC and another a 250mm IC -- but they both have the same angle of view if using the same film format. Similarly, any pinhole, regardless of pinhole size, will have the same image circle if the distance between the film and the pinhole is the same -- in other words, if it's treated as the same focal length. And they will have the same angle of view if using the same film format. The only difference is that one of the two pinhole images will be sharper than the other because one of the pinhole sizes will be closer to the optimal focal length for the pinhole size.

Shorter focal length lenses have wider angles of view, and may or may not have larger image circles. They also have more light fall-off & resolution loss. Smaller pinholes have shorter focal lengths and have wider angles of view if you are willing to accept the light fall-off & resolution loss.

 

[DWThomas]

The angle of view and the image circle are normally separate entities with a typical lens.

Indeed, but we are not talking about lenses. As discussed, the limitation for coverage is mostly a function of what the pinhole camera maker will tolerate. Many lenses will essentially cut off with hard vignetting. The pinhole image circle is more of a soft continuum. Off axis the actual pinhole to film distance is varying and also the pinhole becomes an ellipse; I vaguely recall the the variance is the 4th power of the cosine or some triggy thing. Because what passes for a nodal point is exactly at the pinhole and not somewhere inside a multi-element lens sticking out the front of the camera a lot of stuff can create obstructions was one of my concerns here.

But truth be told, we are all perhaps overthinking this! For WPPD 2014 someone submitted a photo taken with the "Saltine 13" using a cracker for a multi-pinhole plate. (Purportedly a standard saltine has 13 holes in it!)

 

[xkaes]

Indeed, but we are not talking about lenses.

I agree, but I thought the discussion was drifting in that direction. A pinhole has a focal length, like a lens, but it does not have a angle of coverage like a lens -- and people should not think of short focal length pinholes as being "wide-angle" pinholes. And how wide the angle of coverage for any pinhole is simply how much light fall-off the user is willing to accept. Here's a Cosine-4 graph that shows how dramatic the fall-off is -- you can compensate to some degree with center filters.

 

[cliveh]

Does the above chart indicate an optimum range for pinhole camera width and height?

 

[Jim Jones]

No. It does show the loss in image brightness for (presumably) a perfectly sharp-edge pinhole. Most pinholes will show even more fall-off due to the thickness of the pinhole edge. The optimum characteristics of a pinhole depend on the photographer's preferences.

 

[Chan Tran]

I think pinhole favors large format. I tried pin hole with the 35mm and the result isn't good.

 

[TomS6]

I put a shutter from a decrepit folder on my 4x5 pinhole camera with a 50mm focal length. It works well and is very convenient, though between the thickness and diameter of the hole for the lens it vignettes a bit in the corners.

A box camera might be another good source for a shutter. I opened up my Brownie Target 616 which you can trip at the one speed of ~1/50 or pull a lever to trip at what amounts to B. The shutter mechanism is pretty flat and looks like it would be easy to transplant.

 

[DWThomas]

I think pinhole favors large format. I tried pin hole with the 35mm and the result isn't good.

That is the impression I get. I'm too old and lazy to spend too much time on some actual math , but I think the whole concept is to find an acceptable combination of resolution and diffraction. With shorter pinhole-to-film distance, a proportionately smaller hole is required to get a certain resolution, but then that increases the relative effect of diffraction which is related to the absolute hole dimension (and light wavelength).

I agree that a pinhole can be optimized to an acceptable combination for a certain pinhole-to-film distance, but IMHO it does not have a "focal length" because it doesn't focus but serves as a mask for ray tracing, only to be messed up by the diffraction. If diffraction disappeared, one could probably put some teeny-tiny pinhole on a 35mm camera and get sharp results.

 

[xkaes]

Pinholes are always going to have lots of diffraction -- one reason many don't like the images. The "focal length" is really the flange focal length that provides the LEAST diffraction for any given pinhole diameter. So if you really love diffraction, you can completely ignore the "focal length".

 

[xkaes]

I put a shutter from a decrepit folder on my 4x5 pinhole camera with a 50mm focal length. It works well and is very convenient, though between the thickness and diameter of the hole for the lens it vignettes a bit in the corners.

Adding a shutter certainly creates the possibility of vignetting, especially with shorter focal length pinholes. One more reason to use a lens cap instead.

 

[Donald Qualls]

Vignetting by a shutter can be designed out. I've got a pinhole in a spare shutter for one of my plate cameras; it's mounted so the hole resides just about the shutter leaves, so I'd have to back the front standard up to around 50 mm before vignetting would even be a consideration (this on 9x12 cm).

I've also got a pinhole converted plastic simple camera in 35 mm, with the original shutter mechanism modified to B-only and pinhole mounted behind the shutter paddle, where the original (fixed) aperture stop was. No vignetting despite everything being recessed back into the plastic body. I have a couple other pinhole converted cameras, same thing -- if the lens didn't vignette, the pinhole won't.

Now, if you mount a shutter in front of the hole on a very wide angle pinhole camera, you may include some lens threads or part of the shutter mechanism in every composition.

I might point out that the actual shutter mechanism in a simple "rotary" shutter like the ones in box cameras, Holga/Diana, etc. is very thin once you remove the unnecessary lens mounts and baffles. Remounting the parts from a Holga or Shur-Shot shutter in front of the pinhole even on a pretty wide angle setup ought to result in no vignetting.

 

[Chuck1]

I've seen .05mm laser apertures for sale, debating getting one to try with 35mm, or 120. Anyone ever tried something like that?
And silly question but is it possible to magnify a pinhole (like with a 2x teleconverter, or a magnifying glass? Or many magnifying glasses)

 

[TomS6]

Vignetting by a shutter can be designed out. I've got a pinhole in a spare shutter for one of my plate cameras; it's mounted so the hole resides just about the shutter leaves, so I'd have to back the front standard up to around 50 mm before vignetting would even be a consideration (this on 9x12 cm).

I've also got a pinhole converted plastic simple camera in 35 mm, with the original shutter mechanism modified to B-only and pinhole mounted behind the shutter paddle, where the original (fixed) aperture stop was. No vignetting despite everything being recessed back into the plastic body. I have a couple other pinhole converted cameras, same thing -- if the lens didn't vignette, the pinhole won't.

Now, if you mount a shutter in front of the hole on a very wide angle pinhole camera, you may include some lens threads or part of the shutter mechanism in every composition.

I might point out that the actual shutter mechanism in a simple "rotary" shutter like the ones in box cameras, Holga/Diana, etc. is very thin once you remove the unnecessary lens mounts and baffles. Remounting the parts from a Holga or Shur-Shot shutter in front of the pinhole even on a pretty wide angle setup ought to result in no vignetting.

Now I had to go find that camera.

My 4x5 pinhole camera has a Kodak/Compur shutter from a Kodak Six-20 folder. The pinhole is mounted directly in front of the aperture/shutter blades, but that still puts it 1/2" deep in a 1" diameter tube from the perspective of the film plane, which is 50-60mm away. So the vignetting is happening behind the pinhole, not in front of it - or maybe on both sides. I'll have to keep an eye out for something cheap (I like the box camera idea) to cannibalize and take my own advice.

 

[xkaes]

I've seen .05mm laser apertures for sale, debating getting one to try with 35mm, or 120. Anyone ever tried something like that?
And silly question but is it possible to magnify a pinhole (like with a 2x teleconverter, or a magnifying glass? Or many magnifying glasses)

My 75mm f230 pinhole has a diameter of .012 -- and that's pretty long for 35mm. A .05 pinhole is about a 200mm focal length for the best results.

Instead of a teleconverter, just get a pinhole with a wider hole.

 

[DWThomas]

a diameter of .012 -- and that's pretty long for 35mm. A .05 pinhole is about a 200mm focal

Umm -- your numbers sound like inches -- Chuck1 was talking 0.05 mm; that might suggest a sub-centimeter hole-to-film distance.

 

[Jim Jones]

I think pinhole favors large format. I tried pin hole with the 35mm and the result isn't good.

That is certainly true. The size of the blur in a pinhole image doubles as the pinhole to film distance quadruples. Thus, for equal size prints and equal scene coverage when moving from 35mm to 4x5, the print from 4x5 will be twice as sharp as from 35mm. You can see an even greater improvement in sharpness when going to extreme wide angle pinholes and larger film. A properly sized pinhole for 8 inch focal length on 8x10 film yields contact prints that, at first glance, look almost as sharp as a good lens photograph. Contrary to what some photographers say, the size of the pinhole is fairly critical. In my experience, a 10% error in pinhole diameter noticeably degrades the image.