Shutter mechanisms for pinhole

Hi! I'm looking for ingenious ways to open and close the shutter of my camera (but hopefully diy friendly, because my skills and tools are really limited) My hope is that you can share ideas or examples of shutter mechanisms that can fit in a small space. I had some ideas, using one or two pivot points to move a thin piece of plastic or aluminium, but i'm sure i can find a better method if i take some inspiration from others.

- In the first photo you can see that i'm trying to convert a broken Diana plastic camera into a super wide angle 6x6 pinhole camera. There's not much space there for a shutter. Besides, I want to put that filter ring on top, so the shutter must fit between the mdf piece and the filter ring.

- In the second picture, i proudly show my big pinhole camera (made by me with my limited skills and tools) It has a sliding shutter and a filter ring so i can put a lens cap on it (or filters, or both). That's just to show that i like some redundancy. A piece of black tape, or just the lens cap is not enough for me. My idea was to use the sliding shutter to take the pictures, but the problem is that it has too much friction to operate smoothly (my awesome skills, again... but at least it stays closed), so i just use it as a safety mechanism, and instead i remove the lens cap to take the picture

If you're curious, my plan for this converted Diana is to get a professionaly made pinhole. The focal length is just 24mm, so the pinhole must be smaller than 0,2mm. I made docens of pinholes with the needle method, and never got anything smaller than 0,27mm. Besides, for a pinhole this small and a large negative i want it really thin and clean. The space for this shutter mechanism i want to make is just that circle over the mdf piece, about 42mm diameter and 5mm height

Any comments will be appreciated!

See this recent thread:

Dustin McAmera said:

See this recent thread:

6x9 DIY PINHOLE camera

I am thinking on making some kind of a pinhole camera front on which i could attach my 6x9 roll film back (the Graflex 23 type). Any suggestions?

www.photrio.com

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I skimmed through the thread and found the idea of using a fridge magnet. Interesting, and worthy of further exploration, no doubt, but there's not much more about shutter mechanisms in that thread, really... I'll keep exploring on previous posts when i have some time, of course. Thank you!

Call me a conservative simpleton, but I'd just use a lens cap (or something fashioned into a cap shape) and call it good. Pinhole exposures are generally long anyway, so there's sufficient time to fidget with a cap.

koraks said:

Call me a conservative simpleton, but I'd just use a lens cap (or something fashioned into a cap shape) and call it good. Pinhole exposures are generally long anyway, so there's sufficient time to fidget with a cap.

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BINGO!!!

At f200 who needs a shutter?

If you want cute, buy a messed up folder with any cheap shutter that has a T or at least B setting (to be cost effective, can go up with Compur etc), strip it off of its lens and use shutter in T. Typically "T" almost always works on these old folders, just be sure it does have a T (B is almost as good for this).

It's just a matter of mounting pinhole in it.

xkaes said:

BINGO!!!

At f200 who needs a shutter?

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If you want a shutter may as well make it auto exposure. It's easy enough.

I have an ancient shutter that I ripped the meniscus lens from, It has T and B settings (don't bother with the 'I' setting. In place of the lens I put a pinhole plate in the back. I've used it on a couple of pinhole cameras with success.

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!

grahamp said:

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!

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How do you determine hole to film distance?

Hassasin said:

How do you determine hole to film distance?

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Measure from the film plane to the surface where the pinhole plate will mount. This might have to be done in a couple of measurements (and without the pinhole plate in place). Whilst writing, I'll attempt to attach a couple of my versions of a fairly generic drawing similar to what @grahamp describes. This was done because at wide angles it is surprising what 'stuff' can get in the way!

The dimensions in those drawings were specific to plans being considered and not absolute recommendations by any means. The little 'pincers' out at the front represent the minimum clear diameter needed at that distance to avoid vignetting.

I have built a number of swiveling flap shutters, but they were on flat surfaces that had lots of room. I also did one spring loaded cable release sliding flap shutter on a pinhole body cap for my Bronica SQ-A, but alas, that was not a trivial exercise (and I've since sold the metalworking equipment). So I would say working in a shutter assembly with pinhole instead of a lens is likely your best approach, especially if you want to use a cable release.

The thumbnails in the fifth row in my Thru a Pinhole gallery will take you to the construction details for four items I've made.

xkaes said:

BINGO!!!

At f200 who needs a shutter?

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Wel-l-l, my first shot at pinhole in this millennium I figured '3-digit f-stops -- I'll need some FAST film' and bought some 400 ISO stuff. Came to find out that put the exposure times down at the barely 1 second level which is hard to time accurately with a wonky flap shutter and also makes camera shake more likely fumbling around. So I bought some 100 ISO stuff. (This was when I was messing around with a pinhole lens board for my B&J 4x5.)

DWThomas said:

Measure from the film plane to the surface where the pinhole plate will mount. This might have to be done in a couple of measurements (and without the pinhole plate in place). Whilst writing, I'll attempt to attach a couple of my versions of a fairly generic drawing similar to what @grahamp describes. This was done because at wide angles it is surprising what 'stuff' can get in the way!

I have built a number of swiveling flap shutters, but they were on flat surfaces that had lots of room. I also did one on a pinhole body cap for my Bronica SQ-A, but alas, that was not a trivial exercise (and I've since sold the metalworking equipment). So working in a shutter assembly with pinhole instead of a lens is likely your best approach, especially if you want to use a cable release.

The thumbnails in the fifth row in my Thru a Pinhole gallery will take you to the construction details for four items I've made.

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I asked because hole to film plane OPTIMAL distance is directly governed by pinhole size and nothing else. So both, the post I responded to and your diagrams continue to have me confused how your approach is supposed work.

koraks said:

Call me a conservative simpleton, but I'd just use a lens cap (or something fashioned into a cap shape) and call it good. Pinhole exposures are generally long anyway, so there's sufficient time to fidget with a cap.

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Even when taking exposures of 3 seconds or less? Yes, there's sufficient time, but for me it's really combersome

Hassasin said:

If you want cute, buy a messed up folder with any cheap shutter that has a T or at least B setting (to be cost effective, can go up with Compur etc), strip it off of its lens and use shutter in T. Typically "T" almost always works on these old folders, just be sure it does have a T (B is almost as good for this).

It's just a matter of mounting pinhole in it.

Click to expand...

I appreciate the idea, and i'll look for old cameras, but i don't expect to find anything under 40 or 50€, even if they're beaten up. My plan didn't include any buying, only DIY

Hassasin said:

I asked because hole to film plane OPTIMAL distance is directly governed by pinhole size and nothing else. So both, the post I responded to and your diagrams continue to have me confused how your approach is supposed work.

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That's right. The size of the pinhole determines the focal length -- which determines the flange focal length for infinity. Divide the focal length by the diameter of the pinhole, and you have the f-stop. E-Z-P-Z:

http://www.subclub.org/fujinon/pinhole.htm

Aaalbores said:

I appreciate the idea, and i'll look for old cameras, but i don't expect to find anything under 40 or 50€, even if they're beaten up. My plan didn't include any buying, only DIY

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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.

Aaalbores said:

Even when taking exposures of 3 seconds or less? Yes, there's sufficient time, but for me it's really combersome

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I know what you mean. Taking off and putting on those lens caps really wears me out. The only thing worse is having to recite "one one-thousand, two one-thousand, three one-thousand,....".

Hassasin said:

I asked because hole to film plane OPTIMAL distance is directly governed by pinhole size and nothing else. So both, the post I responded to and your diagrams continue to have me confused how your approach is supposed work.

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My working method is to start with the film format (usually actual dimensions of the exposed area) and the angle of view I want, which might be limited by the camera body used if I'm not making that, and then determine the pinhole diameter.

If one already has a pinhole plate, one could work backwards from that to determine the required distance, then see if it's approximately equal to what the camera supplies. Then if the optimum distance is longer, do some sort of extension for the pinhole mounting. But as I slightly alluded too above, for wide angles, it's really easy to run into trouble. Wide angle lenses get entangled in retrofocus and such; sort of a bundle of rays being squeezed into a funnel and then sprayed out again inside the camera body. Pinholes are purely a direct ray trace that needs clear space surrounding the central axis, a dimension that grows rapidly at dimensions perpendicular to the pinhole plate. (Something I have first hand experience with! )

It's also worth noting that different folks have different opinions about a certain constant used in the calculations for a pinhole. That and the fact that the equation produces a rather broad curve seems to make the numbers less than hyper-critical -- at least that's my approach!

To return to the subject of making a DIY shutter to be low-profile and go behind the filter, which is sort of appealing since one doesn't really need the blade mechanism of a full shutter. My opinion is that your sliding shutter, though a neat design, is bigger and more overbuilt than necessary and that's one reason it doesn't operate smoothly.

It may be easier to make a blade shutter out of some thin material on an axle, so that it pivots over the lens rather than slides. It only needs to be somewhat larger than the pinhole recess to prevent light leaks - you could put some felt on the front of the MDF piece to create a light seal between it and the shutter. The shutter blade would only have to pivot by a fairly small angle to cover the pinhole recess. The other end of the blade would stick out beyond the original lens mount, forming a handle you use to open/close the shutter.

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


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.

DWThomas said:

My working method is to start with the film format (usually actual dimensions of the exposed area) and the angle of view I want, which might be limited by the camera body used if I'm not making that, and then determine the pinhole diameter.

If one already has a pinhole plate, one could work backwards from that to determine the required distance, then see if it's approximately equal to what the camera supplies. Then if the optimum distance is longer, do some sort of extension for the pinhole mounting. But as I slightly alluded too above, for wide angles, it's really easy to run into trouble. Wide angle lenses get entangled in retrofocus and such; sort of a bundle of rays being squeezed into a funnel and then sprayed out again inside the camera body. Pinholes are purely a direct ray trace that needs clear space surrounding the central axis, a dimension that grows rapidly at dimensions perpendicular to the pinhole plate. (Something I have first hand experience with! )

It's also worth noting that different folks have different opinions about a certain constant used in the calculations for a pinhole. That and the fact that the equation produces a rather broad curve seems to make the numbers less than hyper-critical -- at least that's my approach!

Click to expand...

I may be reading your post wrong. But key is you are happy with your results, and that is all that counts

Pinhole camera design runs on a catch 22 principle. I think you may be saying this in some parts of your post.

But first, I have no idea what you mean by "angle of view" and how that (apparently) changes with "pinhole size".

The point here is that coverage angle of a pinhole is a relative "constant", meaning it does not change all that much with pinhole size. If one were to change pinhole size thinking it would alter "angle of view" that is not how it works, as increasing hole size in order to "allow" more of a "side" view and enlarge "angle of view" quickly simply ruins image IQ in every part of the frame, not just peripheral areas.

A "circle of confusion" logic can be used in all this, as a "cone of light" that renders each point to recreate image in front, changes its characteristics with pinhole size AND pinhole to film distance, both are mutual, one affects the other.

A pinhole size is generally safest to be smallest possible, but this brings up two issues that need to be accounted for in compromises we make.

Diffraction kills IQ very quickly so there is a point in "smallest pinhole size that ought not be crossed, but also in some hole / negative size pairings, and resulting longer focal distance, that same diffraction that would have been unimportant at smaller focal distance, becomes additional image IQ hindrance, and hole size must be increased to compensate, the latter degrading image IQ on its own.

I basically use 125 degrees as pinhole "angle of view" or as I like to call it "coverage angle" in early design stages.

If we take away curved film plane idea, light fall off, as we move away from main "optical" axis, takes the cake for determining how far we want to go with compromises, or how far away we want to move from film plane with pinhole. So this is indeed a first step in design, the film to pinhole distance, based on "my" 125 coverage angle, which can be used to get starting hole size (being derivative of focal distance). My 125 angle is just a ball park figure allowing for some really bad light fall off to be cut out.

And once a pinhole size is picked, it's the game of finding the best compromise.

Part of this compromise is how good the pinhole is in itself, and is it really the size we think it is. Microscope based examination and direct measurement can go a long way figuring this out, just to rest any potential questions.

As things change with environmental conditions (air temperature/humidity) there is no best answer, no single-always-optimal hole to film plane distance, even if the difference in. the extremes is not all that great. That's where the two competing, and very very old, researches could not arrive at same "constant".

In the end, there is a hole, there is a film, image is created, and we are either satisfied, or we go get a Leica and sleep with free spirits.

Along these lines, the "angle of coverage" or "Image circle" is limited only by how much light fall-off you are willing to accept. If you don't mind a lot -- or have a CND filter -- the image circle can be very large. But that has nothing to do with angle of view -- that's determined by the focal length or distance between the film and pinhole. The closer the pinhole is to the film, the wider the angle of view -- on that size film. The same pinhole, placed farther away from the film, has the exact same angle of view, but the picture angle is much less because only the central part of the image fills up the film.

There also is the circle of acceptable resolution/quality of the image -- which is always smaller than the image circle. Just as with the light fall-off, the quality of the image falls off too, and that's a personal decision -- but the best quality is obtained by letting the size of the pinhole determine the focal length of the pinhole.

So "angle of view" with pinholes depends on what the photographer is willing to accept with light & quality fall-off.. Picture angle is a more pertinent word, but still depends on what's acceptable.

There are three main variables to consider when designing a pinhole camera:
1) film/frame size;
2) the distance between the film and the pinhole - the "focal length"; and
3) the size of the pinhole.
The fourth variable - the angle of view - is determined by a combination of the film/frame size and the focal length. You figure it out by doing ray traces from the centre of the pinhole to the corners of the frame.
The optimum size of pinhole is a function of the focal length.
If you start with a blank slate - all three/four variables are within your control - you can pick which one or two to start with, and then calculate the others to use with them.
If, however, one or more of the variables are picked for you, the desire for optimum results will determine the others.

MattKing said:

3) the size of the pinhole.

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I'm getting pedantic here but the optimal size of the pinhole is also a function of the wavelength of light in which you're imaging. Most calculators use a happy medium as color and panchromatic film is the norm. If you're using primarily orthochromatic or strictly blue sensitive films you can in theory tune the pinhole size to give better performance at those wavelengths.