4x5 Pinhole Camera Design...

Greetings,

 

I had posted a question back a short while ago in regards to pinhole cameras. I received a

lot of great suggestions from some of the more knowledgeable folks on this forum. To

them... I raise a glass of wine to say, "Thank you!"

 

I've recently gotten ahold of a standard wooden graftlock 4x5 back and an appropriate

pinhole (f350 - produced with a Number 8 needle.) Now, my question is, "what depth

should I build this camera (from pinhole to film plane)? What about the height and width?

The plan is that the camera will be built out of mahogony or oak so it'll be fairly stable (as

opposed to a shoe box or similar container.)

 

Ideally, I'd like the entire sheet of film to fall within the image circle of the lens thus

avoiding the vignetting look of some images I've seen.

 

I'll apologize in advance if the answers to my questions "should be" absolutely apparent

but this line of thinking is something I'm entirely uneducated about. Has anyone on this

forum built a camera with a 4x5 back on it before? What were the dimensions of your

camera? I've seen some of the cameras on the various links previously recommended but

I'm still not entirely sure of the appropriate dimensions required for a 4x5 filmback.

 

Thanks in advance.

 

Cheers

Greetings HC.

 

I recently built a 4x5 pinhole camera by using a wooden "craft" box that's designed to

cover a square tissue box with a decorated cover. The back is (currently) a 4x5 polaroid

back.

 

It's 13cm deep (about 5 inches). The image has no vignetting and is pretty "normal" in

focal length.

 

Incidentally, I notice it's world wide pinhole day soon: http://www.pinholeday.org/org/

 

Best wishes,

 

Peter<div></div>

Pretty much whatever focal length you want, or even with a zoom! However the optimal size of the pinhole itself changes with the focal length (a balancing act between adequate illumination and adequate focus) so be prepared to make more holes.

<p>

In "Adventures with Pinhole and Home-Made Cameras" (John Evans, 2003, Rotovision) optimal pinhole sizes are given for focal lengths between 5mm and 1000mm - and they range from 0.08mm and 1.20mm.

<p>

This one I made a couple of years ago has two focal lengths 90mm and 200mm - one reason for the double option was that I want (at some point, not done yet) to try using slits instead of holes, and two slits rather than one alone.<div></div>

You can see that I used a covering plate for the film holder - and that the rear face is open. Reason for that is if I turn the cover plate around (which closes both ends) I can clip on a Polaroid holder.

<p>

If you design your camera around the film holder you should have no problem with vignetting.<div></div>

Since the definition of f-number is focal length divided by aperture diameter, when you say that your pinhole has f-number 350, you are implying a specific focal length. A table I found on the internet gives the diameter of a Number 8 needle as 0.58 mm (<a href="http://jerryo.com/formula/pinhole.htm">http://jerryo.com/formula/pinhole.htm</a>), so if you want your pinhole to be f/350, the focal length should be 200 mm. This is one possible answer to your question about "what depth should I build this camera (from pinhole to film plane)?" This focal length is modestly longer than normal for 4x5. But nothing need be exact in pinhole photography, so feel free to use the pinhole for a different focal length.</p>

 

<p>The other way to approach your camera depth (focal length) question is usually referred to as the "optimum pinhole diameter" question.

For a given focal length, there is an optimum diameter for image sharpness. Flipping this around, for a given diameter, there is an optimum focal length. These ideas are based on balancing the two factors that reduce sharpness in a pinhole. A pinhole that is too large will reduce sharpness because the pinhole wil geometricaly cast a large blur circle. A pinhole that is too small will produce an unsharp image due to diffraction. So the "optimum" pinhole is neither too small nor too large, so neither of these two effects dominate. The first equation was developed by Lord Rayleigh (e.g., <a href="http://www.pinhole.cz/en/pinholecameras/pinhole_01.html">http://www.pinhole.cz/en/pinholecameras/pinhole_01.html</a> or <a href="http://www.geocities.com/markhahn2000/pinhole_concepts.html">http://www.geocities.com/markhahn2000/pinhole_concepts.html</a>).

Using this equation and the diameter d=0.58 mm, the equation gives the optimum focal length as F = 170 mm. This is a bit shorter than the other reasoning, but the idea of "optimum" pinhole is rather indefinite, so the two values are completely consistent.</p>

 

<p>Probably most users of pinholes prefer a wide view, which suggests a shorter focal length than 200 mm. "Normal" for 4x5 is about 150 mm. You might make the depth of your camera adjustable, so that you can experiment with different focal lengths -- or make two cameras of differing depths. If you want to try a focal length much shorter than 150 mm, you might want to try a smaller diameter pinhole.</p>

 

<p>If the material that you made the pinhole from is sufficiently thin, there shouldn't be any problem illuminating all of a 4x5 film, when you use the pinhole at 200 mm from the film. As long as you make the height and width larger than 4x5, the camera box shouldn't cause vignetting.</p>

 

<p>If you want your pinhole to fall on the standard f-number sequence, you might want to call it f/362 -- this is 8 stops less light than f/22.</p>

Good answers. In practice, I have found longer "focal length" cameras relative to film size to be less sharp. Stick your camera right in the face of something to exploit the pinhole quality. A lot of large format photography would do well to get closer, as Kodak always admonished. Besides Mr. Briggs, the best source on the geometry of pinhole photography that I know is G. Penate. He can be reached through the Pinhole Resource web site and he has made pinholes for me. The fellow in the upper Midwest is also excellent. My article on Luminous Landscape shows a 4x5 camera like you suggest. I always build them right around film holders, as another post shows and which is right in the spirit of pinhole photography. You don't need old, weighty, bulky cameras or fancy Leonardo kits. Just do it yourself and it will be more fun and rewarding. Virtually anything can be turned into a pinhole camera: mailing tubes; holiday cookie tins; paint cans; cigar boxes; oatmeal containers, but it is nice working with a film holder out in the field to get multiple exposures per camera. I am not a big fan of Polaroid film but it is also an option. The vintage 4x5 falling plate cameras like the Western Cyclone would make a great pinhole camera, if we go the conversion route. There is a whole slew of recent stuff featuring non-planar film planes and, of course, multiple pinholes per image is always popular. Pinhole photography is also great for multiple exposures and "time and motion" work. Don't rule out color negative and even color transparency materials-the exposures can be timed appropriately. The larger the negative size, the better the result.

Excellent answers, all.

 

I'd just like to add that in my recent images I've taken to shooting closeups of toy soldiers and other miniature figures, with a near-optimal pinhole aperture camera.

 

I've noticed in the resulting images that objects close-in to the pinhole (we're talking ~2 inches) are noticably less sharp than background detail. Keep in mind this is with a near-optimal pinhole camera.

 

Complex math aside, simple ray tracing on paper shows that pinhole images lose sharpness when the subject is very close to the aperture.

 

Which leads me to believe that the optimal pinhole diameter is assumed to work for objects at infinity. Significanly closer, and you should make the aperture somewhat smaller.

 

If the majority of a your work will be done with close-in subject matter, and image sharpness is important, I'd recommend a pinhole aperture about 20% smaller than what the Rayleigh Criteria would suggest.

If the majority of a your work will be done with close-in subject matter, and image sharpness is important, I'd recommend a pinhole aperture about 20% smaller than what the Rayleigh Criteria would suggest.

 

Thanks for that observation. I will try and look for it.

I recently made a pinole camera out of a 4x5 microscope attachment. I was almost done taking the 4x5 back off of the microscope attachment, one day, in preparation of making a wooden pinhole box when it dawned on me... I have the box already. I measured for the pinhole and made a pinhole that is right for a 250mm pinhole camera. I then wanted to play more and took a used (unused) copal shutter and with the help of the machine shop artisan's, had a turret made and a few more pinholes drilled leaving one of the holes wide open for a viewing hole. It's almost as fun as my Holga!

Whats wrong with simply mounting a pinhole on your field/view camera lensboard?

Greetings All,

 

Thank you all for sharing your knowledge on this fascinating topic... and I really appreciate

the pictures of your cameras, Peter and Sandeha. Were your cameras designed through

trial and error or through some method(s) of calculations?

 

It looks like there's a LOT more to pinhole cameras than what first meets the eye. So, I'll be

doing some more research into these cameras.

 

And, Michael, thank you kindly for your information... your response provides much food

for thought (as usual.) I wasn't aware of how to do the calculations and thought it was

based more on trial and error. So, it sounds like the way to get the sharpest image is to

have a smaller focal length (and, therefore, a smaller pinhole.) The only drawback to this is

that it'll take a lot longer to make the exposure and there will be some distortion at the

edges...

 

I also like the idea of the "adjustable" focal length... I'll have to give this a try.

 

Thanks again...

 

Cheers

Greetings All,

 

Thank you all for sharing your knowledge on this fascinating topic... and I really appreciate

the pictures of your cameras, Peter and Sandeha. Were your cameras designed through

trial and error or through some method(s) of calculations?

 

It looks like there's a LOT more to pinhole cameras than what first meets the eye. So, I'll be

doing some more research into these cameras.

 

And, Michael, thank you kindly for your information... your response provides much food

for thought (as usual.) I wasn't aware of how to do the calculations and thought it was

based more on trial and error. So, it sounds like the way to get the sharpest image is to

have a smaller focal length (and, therefore, a smaller pinhole.) The only drawback to this is

that it'll take a lot longer to make the exposure and there will be some distortion at the

edges...

 

I also like the idea of the "adjustable" focal length... I'll have to give this a try!

 

Thanks again to all of you...

 

Cheers

I work in 3D rather than by design, but all I had to work out were the practicalities to support the pinhole holder at one end and the film holder at the other - with no obstructions in between. I made the first one with shoebox card, glue and gaffer tape, and then later I made a 60mm from strips of light craft bass wood like the one above. Careful measurement and cutting counts for a lot, but trial sketches of the angles in a plan drawing can help. This kind of light wood turns out to be quite strong if the angles are properly reinforced and it paints up very easily with a matt black emulsion.

Sandeha,

 

Thank you again for your suggestions... I'm looking forward to building my first! :)

 

Cheers

I have made many pinhole cameras. My first was in a quaker oats box. I built a square platform on the "front" on which to mount the shutter which was constructed of cardboard in the guillotine fashion. In front of that was a cardboard holder where you could put in various diameter pinholes sandwiched between more cardboard like a waterhouse stop. I painted it black with India ink because everybody knows pros use black bodies. Then I cut out letters to spell "Nikon" from more cardboard and painted them red with my mothers nail polish. A light trap was built inside the lid and a piece of plywood drilled for a 1/4-20 Tee nut made a tripod mount. Later cameras up to 30x36 format using paper negs which contact print just fine, and interchangable cardboard film holders with dark slides in 20X24 format were cool, but never as pleasing as that little black oat box. Now I manufacture fine quality folding field cameras in ULF sizes, but your discussion has taken me back to what was a very enjoyable part of photography for me. Thank you all.