My spouse is looking for a special-purpose lens for scientific purposes, and I don't know enough about weird lenses to help. I hope someone here can...
They are looking for a 50mm C-mount lens (or they can adapt to other mounts - they don't need autofocus or iris control) that's as fast they can get (to use in very low light conditions). The tough part is that they need a minimum focus distance of less than 270mm (10.6 inches). They don't care if it's pretty soft. Very fast is important, though. They aren't very cost sensitive; they can spend several thousand dollars. It is to be used with a 1/2" sensor in an industrial video camera.
He's found a Zeiss f/2.0 (Makro-planar T 2/250 ZF). However, is there any other ~50mm lens available, usable for that short focus distance, that's even faster?
Thanks for any help you can provide,