c-mount lens : infinity focus is not working

[noplacia]

i have a WIDE ANGLE C-MOUNT LENS BOLEX KERN HOWELL 1.3/12.5mm, using it on my gh-1 with a c-mount adapter made in hongkong, and infinity focus is not working..

is it the adapter? or the lens?

or do i have to 'filed down' the lens? btw : what is exactly 'filing down' the lens? do i have to machining the back of my lens?

when i hold the lens by hand to the sensor, i can have the infinity focus..

is there a c-mount adapter with a good size to get infinity focus without 'filing down' the lens?

 

[Chibs]

This is a Cosmicar TV lens, and has nothing to do with Bolex, Kern, or Howell. You have to check if it fits the adapter completely, the back of the lens has to be no more then 37mm (If I recall correctly?) to fit completely in the adapter.

 

[noplacia]

thanks Chibs, i think the lens is not fit completely to the adapter..

do i have to machining the back of the lens?

 

[gmoe]

you betcha, you got to machine that lens to achieve infinity focus... if you have a lathe or dremel you can try it otherwise you have to go to a machine shop and have them do it..