I am pretty new to pinhole photography and I need some advice.
I am almost finished putting the camera together.
The length from the pinhole to the film plane is 45 mm I expect to shoot Kodak tmax 100 film. The frame size will be 24 mm high and anything from 24 mm to about 50 mm wide. I included a removable mask so I can shoot wider than normal images.

I used a pinhole calculator ( http://www.mrpinhole.com/calcpinh.php ) and came up with a pinhole size of .283 mm and an f stop of 159 and an exposure time of a half second.

Now that seems to be a problem because how can I reliably expose the film with a manual shutter of a half second.

So I went back to the pinhole calculator and plugged in a couple of other pinhole sizes without changing any of the other parameters and found that if I reduce the pinhole diameter by about ten percent (down to .255 mm) then the exposure time goes up to 1.22 seconds. Using a manually operated shutter I’m sure I can approximate 1.22 seconds more accurately than one half of a second.

So the question comes down to the following:
Should I use an undersized pinhole diameter and a better approximation of the exposure time or should I use the correct pinhole diameter and a poorer approximation of the exposure time???

I understand that I could insert a neutral density filter inside the camera to extend the exposure time but I’d like to avoid that if possible.

Thanks for any suggestions.

Dick Bromberg

What if you rated the 100 at half the box speed and developed accordingly? Or go to a 50 asa film? But I use an old studio shutter and I can get shutter speeds at 1/2 sec very consistantly. Same with a Packard shutter. I've seen guys use the lens cap and get pretty consistant at 1/2 sec. 1/2 sec is still pretty slow.

What if you rated the 100 at half the box speed and developed accordingly? Or go to a 50 asa film? But I use an old studio shutter and I can get shutter speeds at 1/2 sec very consistantly. Same with a Packard shutter. I've seen guys use the lens cap and get pretty consistant at 1/2 sec. 1/2 sec is still pretty slow.


I am not familiar with this process. The pinhole calculator shows an exposure time of about two seconds for asa 50 film. That would be fine, but how do I adjust the developing time to accomodate this? Do I just cut the developing time in half??

Dick, Yes you would reduce the development time. By how much depends of a few variables, such as developer type, temp, technique...ect...ect. Your best bet would be to shoot a few sheets and test. You will dial it in eventually. Just develope a consistent work flow. Processing the film coming out of a pinhole camera is no different than shooting the same film in any other camera and processing. Also if the problem you are having in achieving 1/2 sec exposure or even a 1 second exposure is because you are trying to use a stop watch to time your exposures then I suggest you put the stop watch away and try just counting. Something along the line of..one one thousand. You'll find it much easier and with a little practice you can get extremely accurate. Also don't forget to account for film reciprocity which will increase your exposure times also.