Do these pinhole design numbers look OK?

[adelorenzo]

I'm planning to build an 8x10 inch pinhole camera. I have a set of pinholes that range from 0.1mm, 0.2mm....1.0mm.

I went to the Mr. Pinhole site and plugged in the numbers. It suggested this would be the optimal design. I've never done this before so I was hoping someone more experienced could take a look at them before I start building.

 

[DWThomas]

It sounds workable. My 8x10 has a shorter "focal length" so the numbers are a little different (and I used Pinhole Designer), but I consider pinholery a rather inexact science anyway!

 

[Jim Jones]

For pinhole photographers who like the sharpest possible photos, wide angle cameras beat those with normal or longer focal lengths. The reason for this is the image sharpness with a optimal size pinhole is related to the pinhole diameter. The shorter the focal length, the smaller the pinhole and the sharper the image on the film will appear at a normal viewing distance. This does not mean small format pinhole cameras render the most detail. We tend to enlarge or at least look closely at small photographs. The detail in an optimally sharp pinhole camera does not increase proportionally to the focal length, but at a slower rate, .7 as fast as the focal length increases. A wide angle 8x10 pinhole camera can produce a photograph of some subjects that appears fairly sharp at normal viewing distances. Although I once struggled with a pinhole camera with a focal length of about 24 feet to shoot an eclipse, I almost always stuck to wide angle pinholes. They do have one disadvantage. The light falls off in the image corners. This fall-off is at least two stops when the camera covers 90 degrees. Sharpness also decreases. The charts below compiled decades ago show this.

 

[adelorenzo]

OK, you both have convinced me to try a shorter focal length. I went with the 0.5mm pinhole and this is what I got, it may not cover the entire negative but there is only one way to find out.I started building it last night.

 

[NedL]

There you go. When I started reading this, I was about to suggest a shorter "focal length" and a smaller pinhole. I've got an 8x10 pinhole camera with a 5 inch "focal length" and I used a 0.43mm pinhole ( I use a little smaller constant in the equation, and also use blue light wavelength since it's for paper instead of film ). For a 5.5" FL with 550 nm ( green -- a compromise for pan film ) and my smaller constant, I get 0.46mm for yours ( and 0.52mm using Rayleigh's constant of 1.9 ). I think 0.5 will be fine. If you use blue-sensitive x-ray film in it, you might try your 0.4mm pinhole and see which one you prefer, but 0.5 and 0.4 are both going to work pretty well I think. Have fun!

 

[awty]

My 8x10 is .5mm hole and only about a 50mm focal length. Gives a nice wide 110 angle.
If you can make to focal range adjustable I would recommend that. The calculator is just a guide.

 

[adelorenzo]

There you go. When I started reading this, I was about to suggest a shorter "focal length" and a smaller pinhole. I've got an 8x10 pinhole camera with a 5 inch "focal length" and I used a 0.43mm pinhole ( I use a little smaller constant in the equation, and also use blue light wavelength since it's for paper instead of film ). For a 5.5" FL with 550 nm ( green -- a compromise for pan film ) and my smaller constant, I get 0.46mm for yours ( and 0.52mm using Rayleigh's constant of 1.9 ). I think 0.5 will be fine. If you use blue-sensitive x-ray film in it, you might try your 0.4mm pinhole and see which one you prefer, but 0.5 and 0.4 are both going to work pretty well I think. Have fun!

Interesting, I didn't realize that the wavelength of light is a factor. What number do you use for paper? I tried the equation with 495nm and it suggests about 126mm would be optimal focal length for a 0.5mm pinhole.

 

[NedL]

I usually stick in 480 or 490nm wavelength -- but I also don't think of it as a super-exact science and when I like one pinhole vs. another I don't think it's about sharpness but more of an overall "look and feel". Over time I've found that I tend to like the images made with slightly smaller pinholes ( than suggested by the equations ) better. I don't really know why -- possibly the paper is UV-sensitive enough that it really is a matter of shorter wavelength, but I've played around with different size/shape pinholes enough to see that the "blur" caused by diffraction looks a little different from the blur caused by geometry, so it could be that I prefer the look of diffraction blur Anyway, I'm talking about very small differences here.. like using 0.23 instead of 0.26mm -- and not something you'd easily see if you compared them side by side -- I've just noticed that the ones I tend to like the most also tend to be slightly smaller than the calculated values. I only have one pinhole camera with a pinhole as big as 0.5mm and it's got a "FL" of 8-1/2 inches ( a big popcorn tin for 11x14 paper! )

You'll probably be surprised how much detail there is on an 8x10 inch pinhole image... it's impressive. They look really cool, you're going to have fun with it.

 

[narsuitus]

A few years ago, I made an 8x10 inch single-shot flat film plane sheet film camera from foam board (see black camera in attached image).

The pinhole diameter was .016 inches (.406mm).
The Pinhole/Film distance was 5 inches (127mm).
The horizontal angle of view was 115 degrees.
The f/stop was f/360.

My 8x10 produced great images but I stopped using it because it was so much easier for me to shoot and process 4x5 inch film instead.


Pinhole Cameras by Narsuitus, on Flickr

 

[adelorenzo]

Thanks everyone for the help! I ended up going with something around 130mm focal length for 8x10. So far I've tried a 0.5mm and a 0.4mm pinhole.

I have a box of old Ilford single weight paper that I'm using for negatives. The days are too short to do any exposure testing so I'm just winging it for now. These are scans of the paper negatives but I have contacted printed them and they turn out well.

Here's the camera:


My first ever pinhole exposure! My light meter died in the cold so I just guessed at about a 5 min exposure. This is the 0.5mm pinhole.



Here's my second try a couple of days later. This was 9 minutes using the 0.4mm pinhole.

 

[Nick Dvoracek]

https://pinholica.blogspot.com/2019/01/diffraction-action-six-pinhole-sizes-at.html

I'm planning to build an 8x10 inch pinhole camera. I have a set of pinholes that range from 0.1mm, 0.2mm....1.0mm.

I went to the Mr. Pinhole site and plugged in the numbers. It suggested this would be the optimal design. I've never done this before so I was hoping someone more experienced could take a look at them before I start building.

View attachment 233357

 

[Grandpa Ron]

I have read, studies and experimented with various pinhole cameras. I have discovered that often theory hits the cold light of reality.

While one can order laser cut pinhole of practically any size. I have found the pinhole is the easiest part of the set up. I have made very nice .014" (.356mm), .017" (.432 mm) and .025" (.635) with needles and pop cans. So far my best shot have been with an f number of about f 360 with a .014 pin hole and a 4x5 format view camera. I have used Lord Rayleigh's numbers as a starting point.

The real problems have been.
* Keeping things light tight.
* Processing 4x5 sheet film.
* Making a practical shutter.
* Reciprocity on exposures longer than 30 seconds.
* Scanning negative in to computer. I am working on a contact printer.
* and as strange as it sounds, reducing light reflection inside the camera and bellows once the shutter is open.

I made some really nice 35 mm pinhole photos but viewing then on a computer monitor is too large of an enlargement. so I switched to 4x5.

Attached is my latest photo of Chief Menomonee post elsewhere. This was shot during a brief period of sunshine on a cloudy day. it is a 14 second exposure.

Adelorenzo, you first shots look very nice. Keep us posted.

 

[Andrew O'Neill]

I'll bet those numbers are fine. I used that site to work out exposures and they have been good so far...

 

[Deleted member 88956]

Interesting, I didn't realize that the wavelength of light is a factor. What number do you use for paper? I tried the equation with 495nm and it suggests about 126mm would be optimal focal length for a 0.5mm pinhole.

In theory it does, in practical terms it doe snot. There are way too many accuracy issues with camera itself, pinhole QUALITY in particular, and overall put-together exactness, that wave length is last thing to tinker with. When you get the rest into level of perfection where wave length becomes the limiting factor, please do let me know.

And to start your build, while calculators will get you in the right area, make (or purchase) the pinhole FIRST, then measure its actual size, then reverse-engineer that into original camera idea, so adjustments are made after the pinhole itself is on hand. This would be a required step before wave length were to be tinkered with, but again ... there is no need for either. Three is no agreement in science on what makes pinhole imaging tick 100% and as such there are only approximations and compromises, and every box made makes the final result different.

The latter is not meant as discouragement, this is fun, results are worth it, even if the model will have chased you with a fork for the rest of your life