Customizable Yashica / Bay 1 lens hood

thingiverse

This is a hood for an external Bayonet I mount on a Yashica-12 with 80mm lens with 23.3mm front glass. I made this hood to be as narrow as possible without vignetting on 56mm x 56mm film, so it would provide as much protection as possible without getting in the way of the sighting lens. If your front glass is set back further from the front of the lens assembly, or has a larger diameter, or a shorter focal length, you will need to adjust focal length, glass diameter or glass inset parameters to avoid vignetting. On my Yashica, the shutter speed and aperture knobs are very close to the lens, so I had to make the bottom of the hood pretty thin to clear them. I don't know much about optics, so I hope I computed the hood shape right. I imagined a cone with cross-section equal to the film size (with 2mm of tolerance added) at one focal length distance from the optics, and then took the union of all these cones over the points on the front glass. I then made the hood surround the union of these cones. The code uses my Bezier library for the mount tabs: https://www.thingiverse.com/thing:2207518 And it uses my tubeMesh library for morphing the shape between the bottom and top: https://www.thingiverse.com/thing:2406760 **May 14, 2023 update:** Changed shape to avoid vignetting.