Anyone had adjusted focus points from lens thread/mount wear?

[Pirate]

This question comes about from my 1952(ish) Canon III Rangefinder which uses a Leica Screwmount lens system. When screwed down, the center reference mark goes past the center a bit - I havn't finished a whole role through it yet, and I'm out in Iraq so I'm not having any film developed for a bit. I'm wondering if the wear of the threads on the body/lens effects the focus, or does the mechanics of this focus system will take up that slack and keep things where they need to be?

Anyone?

 

[Doug]

The answer is to have no worries about this. It's common for the lens to turn a bit beyond "center" when seated. Minor differences with different lenses on different bodies don't affect focus either, as the cam/roller behind still relate as they should. Some folks even suggest that turning past center is designed to help the user see the settings through the viewfinder. 🙂

If you can manage it, having one roll processed and printed/scanned would be reassuring.

 

[Ranchu]

I'm not an expert, but the crucial thing is the inner tube of the lens (the part on the back of the lens that moves in and out as you turn the focus when the lens is off) that contacts the little swing arm of the rf mechanism , which shouldn't be affected by the mount threads. I don't think it will matter, but you could post this also in the leica threadmount or canon rf forums.

Edit: Doug beat me to it, good, someone more experienced with these things.

 

[hans voralberg]

The center mark on Canon and Nikon go past center all the time, it'd be weird if they don't 😉

 

[Pirate]

Thanks guys. It makes sense that the roller would keep track of the focus even with wear on the threads, but I had to ask.

P^)

 

[payasam]

Wear of the threads does not affect the correct mating of the lens with the body. Unlike lenses with other kinds of mount, a screw mount lens can always be mounted firmly. As others have said, the position of engraved or painted scales can vary.