Canon 35mm LTM lens made from ''trash''

OlivierAOP said:
Just to clarify: you filed/ground the little wedge on the cam follower that's inside the camera?
Click to expand...

NO. The focusing cam follower in the camera must not be changed. The surface on the back of the lens which the cam follower touches is what needs to be ground to a specific angle, according to focusing throw and nominal focal length.

Phil Forrest
 
Phil_F_NM said:
NO. The focusing cam follower in the camera must not be changed. The surface on the back of the lens which the cam follower touches is what needs to be ground to a specific angle, according to focusing throw and nominal focal length.

Phil Forrest
Click to expand...

Yes exactly!
 
Oh ok thanks. I think one can figure out an angle. The lens/cam movement is f*f/(D-2*f), and the cam follower draws an arc according to the pivot length.
 
Could you share a pic of the modded cam? It seems the cam angle would need to be very steep given the tiny lateral movement of the follower and the ~1.5mm the cam needs to compensate. But maybe I'm missing something...
 
Ahh I'm dumb... I thought the cam on the Industar didn't rotate as you focused. In does, and in that case the cam angle to convert 50mm to 35mm should be approx 3.5 degrees (at 17mm cam radius and 6mm per turn helicoid pitch)
 
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