"PinZIN" - My Pinhole Folding Camera
Veijo Vilva
A Zeiss Icon Nettar 517/16 6x6 folding camera converted into a pinhole camera.
In this photo, the shutter is open and the stainless steel pinhole plate
visible.
I removed the partially broken lenses from a flea market camera leaving just the shutter and inserted a laser-drilled photo pinhole made by Lenox Laser in place of the back lens, which happened to have exactly the same diameter as the pinhole frame. I punched a 3mm hole into a piece of black, self-adhesive velour foil (d-c-fix), fixed it on the anodized back side of the pinhole frame, cut the foil to slightly too large a size along the edge of the frame and pushed the whole into the lens opening behind the shutter. The edge of the foil keeps the assembly quite firmly in place but allows its removal without a danger of breaking anything. I'll probably add some more foil to around the hole in order to reduce the reflections within the camera.
The pinhole to film distance F is about 72 mm and the pinhole diameter D = 0.3mm, which is optimal as calculated from F = sqrt(D/750). The f-stop is 240. The angle of view is 42.5 degrees both horizontally and vertically, and 57.6 degrees diagonally. The photos taken with this camera aren't quite as sharp as those taken with the Zero 2000 because of the relatively narrow field of view, for F = 72mm the negative ought to be about 95mm wide to get the same number of lines/negative width as Zero 2000 gets with its F = 25 mm (the diffraction limit is about 6 lp/mm for f/240 and 11 lp/mm for f/138). However, about 5" x 5" prints ought to be, for many purposes, large and sharp enough, sometimes even larger prints will be OK.
The pinhole diameter of 0.30mm has a tolerance of +/-0.012mm which adds a certain amount of uncertainty to the focusing.
Some of the First Photos
As expected, these photos are much softer than the ones taken with the Zero 2000. In theory, the resolution is only about 0.58 times the resolution of a Zero 2000.
A 10.6mm wide direct crop from the original 3260 x 3260 scan covering
a about 54mm x 54mm area of the negative (a 10 Mpixel file).
The height of the red rectangle equals the pinhole diameter. There
are about 60 pixels/mm.
In the following photos, the camera is almost on the ground.
These are not run-of-the-mill macro photos as the focus is undefined.
The "river" is only about half a meter wide, dewy clover leaves in the
foreground.
A direct crop. The red spot shows the theoretical size of the diffraction
spot at f/233.
Note the dew drops, some of which are smaller than the
diffraction spot.
The very small, sharp, white spots are just dust in the scanner.
A direct crop. It should be noted that the grass wasn't stationary
during the exposure.
The diffraction spot is about 0.25mm at f/233, i.e. narrower than the
0.3mm pinhole. The width of some of the lines in the photo is less
than a third of the width of the diffraction spot.
The nearest rock is only about 5cm high. In the background, flowing water.
A small chess set. The squares are 24mm wide, and the nearest piece is
31mm high,
the distance from the camera is 85mm. The flower pot is 170mm wide at the top.
(a 1024x768 wallpaper,
printable demo photos)
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