Re: Building my first serious pinhole

I have been using my homemade 5x7 pinhole camera for over a year now with
both film and paper negatives. I have a focal distance of 120 mm with a pinhole
diameter of .016 inches (.406 mm) for an aperture of f/295. I am starting to
see falloff at the corners, however it is not objectionable and many do not
notice it at all. The 35mm equivalent to the 120 mm I have is 24mm based on the
height of the negative.

I used 1/2 inch (12mm) plywood from a model shop for the body because this
plywood has 7 layers of wood. The lensboard is 1/4 inch (6mm) plywood. The
pinhole was made from a soft drink can and was taped to a 25mm square piece of
matboard. Because of the wide angle view of this camera, I had to make the opening
in the lens board 25mm in diameter to avoid vignetting. All of the joints for
the top, bottom, sides, and lensboard are rabbeted joints in order to create
light traps. The rear portion of the top, bottom and left panel are also
rabbeted for about 38mm to form a ledge for the film holder to rest against. The
shutter is a sample of countertop material cut to an appropriate shape which
pivots to cover and uncover the pinhole. The right side panel is shorter to
create the 30mm opening for the film holder. The back fits within the top, bottom
and left panels and is held in place with screws from the top and bottom. The
back has two springs from metal picture frames to hold the filmholder up
against the ledge. The tripod socked in the bottom is a 1/4x20 T-nut which is
covered on the inside with a scrap of plywood. The interior is painted flat black
and the exterior is varnished. I drew sighting lines on the top and both sides.

Good luck with your camera and I hope you enjoy it as much as I have enjoyed
this one.

Jim Stewart

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Received on Wed Dec 1 06:40:53 2004