50mm Summicron v4 - blurred at infinity

[BarberShop]

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Hello,

I have a 50mm Summicron v4 which I've been using on film but haven't developed any rolls with yet. Recently I mounted it on my Sony camera and realised that when the focus ring is rotated to infinity, the whole image becomes blurred - much like what happens when you rotate the focus ring of a modern autofocus lens all the way. If I rotate back a little bit, then infinity becomes in focus.

My question is, is this likely to be a phenomenon that only happens when this lens is mounted on a Sony body, or will it likely be happening on my film body too? Note that none of my other M-mount lenses present this issue when mounted on my Sony.

If it's likely happening on film too then is there anything I can do to fix this myself or does it have to be sent for repair?

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[jankap]

That means, that the adapter, that you use the Summicron for the Sony, is a little bit too short. I think, that with your Leica camera (without adapter) infinity will be sharp at the infinity mark. If the adapter were too long (too thick), it would be bad, because then you could never focus at infinity even.

[rocheung]

Gotta get a good quality adapter.

[hansvons]

3 hours ago, BarberShop said:

Note that none of my other M-mount lenses present this issue when mounted on my Sony.

The lens barrel is off. The chance isn’t low that on your film, Ms., the range finder system produces perfectly sharp images, only that at far distances, the marks on the barrel show lower numbers, e.g., 8 metres instead of just about infinity. 

[hansvons]

8 minutes ago, rocheung said:

Gotta get a good quality adapter.

Always a good idea. But this isn’t the culprit as your other M lenses work as expected.

[BarberShop]

11 hours ago, jankap said:

That means, that the adapter, that you use the Summicron for the Sony, is a little bit too short. I think, that with your Leica camera (without adapter) infinity will be sharp at the infinity mark. If the adapter were too long (too thick), it would be bad, because then you could never focus at infinity even.

Any ideas why the problem only presents with this lens and not my other M mount lenses?

[jankap]

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What are the other M-lenses, you mention? Have you tested them very critically at infinity? The moon, a far antenna or building.