35mm film camera

prusaprinters

A simple, all-manual 35mm film camera compatible with Nikon F mount lenses. The only non-printed parts you will need are:-24 6-32 x 3/8 button head screws-1 rubber band-a sheet of 3mm light seal foam To assemble:Place the rewind stem through the left-most tapered opening in the top plate of the body. Cap the square end with the rewind knob and secure it with a screw. Do the same for the winder knob in the right-most opening.Drop the frame counter into the central tapered opening of the chassis.Insert the tube of the top plate into the non-tapered opening in the chassis. The keyway may need to be lightly filed to clear the boss on the tube. Before fully seating the top plate, place the hinge of the door between the slot halves in the top plate and chassis. Then attach the top plate with screws.Slide the stem of the shutter into the tube. Lift the shutter lever over the pin next to the base of the stem, the pin should fit into the slot in the shutter lever.Wrap a rubber band between the boss on the tube and the base of the shutter stem.Get carried away playing with the shutter for a few minutes.Drop the lens locking pin into the recess next to the shutter, on the left.Place the lens lock spring over the lock pin with the nub facing down, and attach it with a screw.Add the film idler cog onto the frame counter. No adhesive should be necessary.Insert the bottom of the body and attach it with screws. It is a tight fit but should go together with some gentle persuasion, lightly sand or file the part if it really doesn't want to go together. Attach it using 11 screws, 6 on the bottom and 5 on the front.Add the 3 door latches to the bottom of the body using screws. They should turn freely but stay firmly in place when rotated over the divots in the door. You may want to file a shallow groove where the latches cross the lip of the bottom plate.Apply a strip of light seal foam around the back of the body where the door contacts.The cable release adapter is optional. I don't have the cable release finalized yet but the basic idea is to use m5 pneumatic fittings with a length of PTFE tube and some filament with a plunger on the opposite end. Focus calibration:Due to variations in printer tolerances, the camera will likely show focus shifts as printed (for example, the test shots I took are without calibration and are therefore quite soft.) To account for this the flange focal distance (the distance from the lens to the film plane) is slightly oversized as designed to allow for the camera to be fine tuned without needing to add material. To test and adjust focus without using film:Mount the camera on a tripod and point it at a bright high contrast scene such as test on your computer monitor and measure the distance from the subject to the film plane (~46.5mm behind the front of the camera. Slight errors in measuring here aren't critical) and set the lens's focus ring to that distance (I test at 5 feet.)Lock the shutter open. I did this by jamming a small screwdriver into the mechanism at the pivot for the shutter lever. Not an elegant solution but it works.Place a ground glass with the matte side against the film gate. A ground glass can be made by taking a flat piece of clear plastic and scuffing one side with fine sandpaper (I use a scrap of 1/8" lexan sanded with 600 grit). You should see an image projected onto the ground glass upside down (turn your room lights off if it is faint.)Move the focus ring on the lens towards infinity, focus should improve somewhat. Return the lens to your starting position. Pull the ground glass away from the camera a small distance, focus should get worse. This means the lens is further from the film than it needs to be. If the opposite is true then the lens is too close and material will need to be added such as a shim between the film and film gate (this shouldn't be the case however.)Slowly sand or file material away from the flat area immediately above and below the film gate. Make sure to keep this area flat and even on both sides. Removing the bottom plate from the camera will make this much easier. Check your progress frequently, You shouldn't need to remove more than a fraction of a mm in total. Once you feel the focus is acceptable you are done. Bear in mind that stopping the lens down will also help account for small errors by expanding the depth-of-field. If you are having trouble evaluating the focus by eye, try using a loupe.To use the camera:Acquire an empty film cassette with a small “tongue” of film sticking out. Tape the leader of your film onto this tongue and make sure it passes the light trap of the take-up cassette.Slip the cassettes into their slots. Twist the take up and rewind knobs until the end of the stems fully seat into the cassettes. Make sure the sprockets of the film line up with the cog of the frame counter and close the back, closing the locks as well.To use the frame counter, turn the winder knob counter-clockwise and make sure the counter spins. If it doesn't, rewind the film and double check the sprockets line up. when the mark on the counter stem lines up with the mark on the top plate you have advanced 1 frame.Advance a couple frames and you are ready to shoot.The only shutter speed is ‘Bulb’, meaning how long you press the button is how long the shutter stays open. You'll probably want to use a small aperture and a slow film to prevent overexposing (a fast actuation is probably 1/10 sec.)Focusing is done by scale, guesstimate the distance to your subject and set the lens for that distance. A smaller aperture will help account for small errors as the depth of field will still cover your subject.As this camera does not have a viewfinder, a wide angle lens (less than 50mm) is probably going to be your best bet. I use a 28mm.Due to the size of the opening in  the shutter mechanism, lenses with large rear elements will likely vignette at faster apertures. The Soligor 28mm f2.8 that I have on mine has a rear element just over ½" in diameter and still vignettes slightly at wider apertures. Update:added version of chassis with clearance for the aperture rings of some lenses. If you plan to use a lens with an aperture ring that sits proud of the mounting surface of the lens use version “chassis- aperture ring clearance”