LTM Adapters on Leica M

[David Murphy]

I've been using my M2 lately with some LTM lenses using Leica and Voigtlander adapters. I may be imagining this, or perhaps I don't have enough images yet to make a sound judgement, but my impression is that the image sharpness is slightly lower than when the lenses are used on a pure LTM camera. The lenses in use have been mostly wide angle 28-35mm F2-F3.5.

Just how good are LTM adapters at preserving the focal plane location? Anyone else have any problems with this?

 

[ferider]

Which adapters are you using, David ?

They can be quite different, which matters particularly for wide angles.

I have had only reliably good results with original Leica adapters. And I use many non-Leica lenses, so I assure you, the brand doesn't matter to me.

Roland.

 

[raid]

I once had to throw away a Japanese adapter as it messed up my camera.

 

[David Murphy]

Well I need to check, but at least one is a Leica-made adapter -- the others are Japanese as I recall. I'm beginning to like the idea of using only native bayonet lenses on my M2.

 

[FrankS]

Why would adaptors matter more on wide angle lenses, Roland? Don't they have more DOF at each f stop than normal and longer lenses at those same f stops?

 

[ferider]

Why would adaptors matter more on wide angle lenses, Roland? Don't they have more DOF at each f stop than normal and longer lenses at those same f stops?

DOF and focal plane sensitivity are two different things, Frank. Wide angles are much more sensitive to focal plane shifts than longer lenses.

Roland.

 

[FrankS]

If that's the case then I've learned something new! 🙂

Focal plane shift via an adaptor is somehow different than moving the lens with the focus helical?

 

[ferider]

Focal plane shift via an adaptor is somehow different than moving the lens with the focus helical?

No that's the same. But the relations are different.

Take a 90 and a 35mm lens. Change focus from infinity to 1m. They both (physically) get longer, FOV decreases. But the 35mm lens, in absolute terms moves only very little (2-3mm, maybe ?) from infinity to close up, much less so than the 90 (a cm maybe ?).

Roland.

 

[FrankS]

Ah, thank you! I don't mind being shown that I'm wrong about something because it means I've learned something.

 

[ferider]

No problem. Vince explained this once to me a while back, kind of counter intuitive .... 🙂

 

[raid]

It makes sense ... now.
I prefer using LTM lenses on LTM bodies, and also FSU LTM lenses on FSU LTM bodies.

 

[David Murphy]

It turns out that the adapter that seems sharper was a Leica-made one. I'll check the run-out of the adapter thicknesses with a micrometer and report back.

 

[Ronald M]

Off brand adapters sometimes are made not exactly 1 mm thick.

I have measureed my Leica and CV ones and they are perfect.

 

[Axel]

My experience with a 50mm Jupiter and a Leica-adapter on my M6 is that there are no differences in terms of sharpness or focussing or anything else to my summicrons with the direct thread mount.

Regards, Axel

 

[Erik van Straten]

I've noticed that original Leitz adapters mount more easely on the camera. Mouting my cv-ones allways make me fear that I will damage the camera. I have to mount the cv-ones exact parallel on the camera, while I can put on the Leitz-ones as easy as an original bayonet Leica-M lens.
I will replace my cv-adapters with Leitz-ones as soon as I can find them.

Erik.

 

[delft]

As I understand it, the adapter doesn't have to be exactly 1 mm thick. The rangefinder is coupled to the thing that moves forward & backward inside the main barrel; so if the adapter were too thin, you would only loose a few cm in close-focus distance.

Greetings,
Dirk

Off brand adapters sometimes are made not exactly 1 mm thick...

 

[ferider]

Again, the movement of RF cam and lens barrel are not the same for either wide angle or tele. For a wide angle the cam moves more than the lens barrel. If the adapter is only a little off, you will loose noticably resolution at infinity.

 

[Sonnar Brian]

As I understand it, the adapter doesn't have to be exactly 1 mm thick. The rangefinder is coupled to the thing that moves forward & backward inside the main barrel; so if the adapter were too thin, you would only loose a few cm in close-focus distance.

Greetings,
Dirk

This is true only for 50mm "normal" lenses where the optics move 1:1 with the RF cam. As Roland stated, When a translation is involved, the difference in thickness will knock the focus off.

 

[delft]

After a good nights sleep, and making a little drawing, it fainally makes sense to me.

Greetings,
Dirk

 

[ray*j*gun]

I agree. If you have the time and resources to plan, I believe that its best to reduce the variables e.g. manufacturing compromises. Sometimes circumstances force compromise but I would never buy an adapter as part of a kit.

Ray

It makes sense ... now.
I prefer using LTM lenses on LTM bodies, and also FSU LTM lenses on FSU LTM bodies.