Pinhole Lens Board - Compatible with all helicoid lens cones (not Mamiya Press/Holga)

This is a replacement threaded lens board, in either standard (M65) or large (M77) helicoid mount. The pinhole lens board contains a professionally laser drilled high quality brass pinhole plate with a standard 49mm filter thread and push on lens cap.

The pinhole can be configured in either 0.2mm or 0.4mm diameter, which is combined with the lens cone to calculate the effective aperture (F number) for metering. 

For example, if the lens cone you are using is for a 90mm lens, you would divide the focal length by the pinhole diameter to obtain the F number;

90 / 0.2 = 450

90 / 0.4 = 225 

You would then use this F number with your film ISO to meter the scene. As the pinhole is mounted to a focusing helicoid, you can also extend the cone by up to 14mm to adjust the equivalent focal length (re-calculating your F number too).

The push on lens cap is used a traditional simple shutter. Alternatively, cover the pinhole with your hand before removing the lens cap and use your hand as a shutter.