Quote Originally Posted by Dr Croubie View Post
Zörk also do a pinhole set, it's meant to be mounted on a lens filter thread and act as a tiny aperture. I got a set cheap off fleabay, I'm just mounting mine direct-to-shutter.

These are no pinholes in the common meaning.

They rather are apertures intended to substitute the original one for a smaller one. To yield larger DOF.

Due to its position it likely is to introduce vignetting and also distortion.