Gianfranco_R
Newbie
Hi to everyone! I'm just new member here on RF! and I take the occasion to present myself! I'm Gianfranco, 23years old, from Bari, Italy! I have to make you a question, I joust bought a Navitron 75mm f1,3 on ebay, it arrived some days ago... well, It's a tv lens, so it's C mount... Since I'm not loocking for closeup shots I would like adapting this lens to the M39 mount, so I could use it on my Zorki 4 and on my Fed 5b!! I did some calculus of compensating the different flange focal distance, and I would be able to make an adapter for the mount... what worries me is how to focus with this lens!! HELP please! 
bmattock
Veteran
Hi to everyone! I'm just new member here on RF! and I take the occasion to present myself! I'm Gianfranco, 23years old, from Bari, Italy! I have to make you a question, I joust bought a Navitron 75mm f1,3 on ebay, it arrived some days ago... well, It's a tv lens, so it's C mount... Since I'm not loocking for closeup shots I would like adapting this lens to the M39 mount, so I could use it on my Zorki 4 and on my Fed 5b!! I did some calculus of compensating the different flange focal distance, and I would be able to make an adapter for the mount... what worries me is how to focus with this lens!! HELP please!
I think you are going to have some problems. If this is a true 'C' mount lens, the flange-to-film distance is 17.526 mm, while a LTM camera flange-to-film distance is 28.8mm. This means that the lens must be sunk into the camera body nearly 10mm.
I think you may also find that the image circle cast by the lens you have will not cover a 35mm frame of film. So even if you manage to create a mount that holds the lens nearly 10mm into the body of the camera, the resulting image will be a small circle in the center of the 35mm film frame.
I'm sorry, but c-mount lenses are not really adaptable to 35mm film cameras.
Gianfranco_R
Newbie
yes man I know this, but suppose I just want a circle in a 35mm frame... how could I combine this lens to the zorki RF??