Screw mount (how tight?)

[Rurouni]

I just acquired a Nokton 50 (yay!) and was wondering how tightly the lens should be screwed into the mount. I usually try to align the 'dot' on the lens barrel at 12 O'clock with the Bessa's meter, but I can tighten a little bit more and the 'dot' ends up a little to the left of 12 O'clock but not by much.

In general should all LTM lens be tightened up to only a 12 O'clock reference? Will there be any performance issues if I don't do so?

Thanks!

 

[FrankS]

A srew mount lens may or may not align perfectly to the 12 o'clock reference dot. Screw the lens tightly with your finger strength without staining. Using hand or arm strength is way too much torque.

 

[petebown]

If you unscrew the lens slightly, it will be further from the film plane and will therefore have a closer focussing distance. The rangefinder coupling should take account of the tightness of the lens. In other words, it makes no difference how tight the lens is, focussing via the rangefinder should always be correct.

I wouldn't overtighten a lens as it may damage the threads. However, I do tighten my lenses onto M converters as these don't need to be unscrewed very often.

 

[Rurouni]

Thanks Frank and Pete for the help, yeah I was wondering if I'm messing up the screw threads. 🙂

I've also realised how spoiled I've been with the Nikon F mount, lenses are so easy to attach! I spent 5mins trying to attach a LTM lens to my Bessa finally realising in horror that I was turning it in the wrong direction... agh! : P

 

[goo0h]

I've also realised how spoiled I've been with the Nikon F mount, lenses are so easy to attach! I spent 5mins trying to attach a LTM lens to my Bessa finally realising in horror that I was turning it in the wrong direction... agh! : P

Does "righty-tighty, lefty-loosey" apply?

 

[doubs43]

Most of my LTM cameras are pretty positive when the lens seats and further tightening would obviously be too tight. I have one - a IIIf - that requires approximately 10 degrees of a turn to properly seat. I plan to have it CLA'd before too long and I'm going to have the mount face checked for flatness.

Walker

 

[pvdhaar]

Most important is not to overtighten when screwing in a lens. This puts a lot of stress on the mount, or in case of an M-LTM adapter on the lens release mechanism. Letting a lens sit loose isn't good either. It may fall off or not get you sharp pictures.

Many of the CV LTM-mount lenses don't align at the 12 O'clock position when they leave the factory, but fortunatly there is something that can be done about it. I've made a couple of picture how I've repositioned the CV25: http://www.rangefinderforum.com/forums/showthread.php?t=14413

Hope it helps..