Film canister camera

[ofofhy]

I figured that a quick and dirty way to get into the pinhole game would be to convert a film canister into a camera. So far, I have done the following: 1) Cut a square hole from an Ilford (all black) canister. 2) Using a needle, place a pinhole into an aluminum square from a can. 3) Using fine sandpaper to remove the burrs. 4) Epoxy the aluminum over the square hole and seal around the aluminum with electrical tape. 5) A flap of electrical tape will serve as a shutter.

I went to Mr. Pinhole's f-stop calculator, and got a value of about f/83, which translates into an exposure time of 1/4 sec for 100 speed film. I plan on using a piece of 35 mm film, curled around the inside of the canister. This seems short for an exposure, but make sense due to the small focal distance. Should I just pull the film enough to get a longer exposure, or does 1/4 second seem do-able with the shutter above?

[glbeas]

You would probably have problems with camera movement from such an arrangement unless you can make a mechanical shutter of some sort. You may be better off using a strip of print paper so the camera can sit long enough without being handled to get an unshaken image.

[ofofhy]

Yeah, the paper is another option. I am looking around our lab to see if there is any oddball microscopy film around that might rate out super slow.

[Greg_E]

ND filter? ND filter and 25 speed film?

[Jim Jones]

There are many ways to prevent movement of a pinhole camera during exposure. I usually incorporate a tripod socket. It is simpler to clamp or weigh the camera down to something solid.

The most common arrangement of pinhole and film in a cylindrical camera is with the pinhole in the side of the cylinder opposite the center of the film. Taking the diameter of a film cannister to be 30mm and using http://www.pinhole.cz/en/pinholedesigner/ with a user constant of 1.5, I get a pinhole diameter of almost .2mm and f/150. This should give near optimum sharpness in the center of the image. A pinhole of about the same diameter can also be placed in the end of the cylinder.

[ofofhy]

Jim,
Your description is pretty much what I have made. Although, I measured my pinhole closer 0.3 mm. It sounds like I should be able to pull the film a couple of stops ~ 25 speed, and when I account for reciprocity, I should get a shutter speed of over 1 sec. I could also use it less than sunny conditions to start. I am fairly confident that I can rig up a tripod mount to keep the camera steady for over a second. It was the 1/4 second that was worrying me.