I plan to make a pinhole camera for pinhole day on sunday and would like to use some Polaroid Image cartridges that I found in my darkroom.
Those are 640 asa which will come in handy as the kids will have to pose .
Can someone give me an indication of the focal length that I need to use to make it wide angle? An aproximate pinhole diameter would also be welcome.
Depending on the size of the film carts you are using, you would want an effective focal length of 50 - 60 mm most likely. In simple terms, the measurment of the film's diagonal would give you the approximate "normal" focal length. Anything less will be wide angle.
A 60 mm FL would be a 0.327 mm hole, according to the above calculator.
Good morning Stefan,
Normal for that film is 118mm focal length using approx .46mm hole. One half normal for a wide angle would be a 60mm with a .34mm hole at f191. I think you could go as wide easily to 40mm with a .267mm hole at f150. Pinhole numbers are very flexible, so for fun don't get stressed about a exact sized hole.
Have fun,
Sam H.
At the Edun site I found the diameter list of my pinholes set because I erased one of the indications.
Then by using Pinhole Designer ( http://www.pinhole.cz/en/pinholedesigner/ ) and a calculator I converted them to millimeters and made a little excel sheet with the focal lengths, f nrs and EV's for all 12 holes.