How to describe the problem with this M lens?

[Jon Warwick]

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I have an M 75m Summarit. It's been to Germany already for repair, but still has the same problem, and hence i will be sending it back (3rd time lucky now!).

Any idea what's occurring here, and what can I say when dropping it off to underline the issue i'm seeing - is a good description simply to say that it's "front focusing", or something else?

- when the lens ring is at infinity, what is tack sharp is only located about 50 metres away

- indeed, the lens cannot ever get to true infinity - ie, the focus ring can't be turned any further to get to where it needs to be to achieve precise focus for very far distances 

- the lack of sharpness at distant objects with this 75mm Summarit is apparent when using the Visoflex 2 on my M11s and comparing "in camera" to other lenses (and obviously in the files on the computer!)

- if i use the rangefinder, what is tack sharp is closer to me than the subject that i've focused on

- I can achieve perfect focus on objects - obviously only up to about 50 metres away - when using liveview

Thanks for any suggestions 

 

 

Edited March 23 by Jon Warwick

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[jaapv]

11 minutes ago, Jon Warwick said:

I have an M 75m Summarit. It's been to Germany already for repair, but still has the same problem, and hence i will be sending it back (3rd time lucky now!).

Any idea what's occurring here, and what can I say when dropping it off to underline the issue i'm seeing - is a good description simply to say that it's "front focusing", or something else?

- when the lens ring is at infinity, what is tack sharp is only located about 50 metres away

- indeed, the lens cannot ever get to true infinity - ie, the focus ring can't be turned any further to get to where it needs to be to achieve precise focus for very far distances 

- the lack of sharpness at distant objects with this 75mm Summarit is apparent when using the Visoflex 2 on my M11s and comparing "in camera" to other lenses (and obviously in the files on the computer!)

- if i use the rangefinder, what is tack sharp is closer to me than the subject that i've focused on

- I can achieve perfect focus on objects - obviously only up to about 50 metres away - when using liveview

Thanks for any suggestions 

 

 

I had exactly the same problem with a 90 AA. Leica never managed to solve it and I traded it in.

[Jon Warwick]

21 minutes ago, jaapv said:

I had exactly the same problem with a 90 AA. Leica never managed to solve it 

i'm a bit surprised the issue with my lens hasn't been resolved - ie, clearly i would assume their testing equipment is amazing, and yet it's really obvious where the issue still sits (to my eyes at least). Maybe whatever is going on is really not easy to fix? 

Edited March 23 by Jon Warwick

[TomB_tx]

1 hour ago, Jon Warwick said:

- when the lens ring is at infinity, what is tack sharp is only located about 50 metres away

I recently had the opposite issue with a new Chinese 35mm "clone": the RF focused fine close-up, but "infinity" objects were sharp at scale / RF marking for about 35 ft. Almost like the RF cam didn't match the true focal-length. DAG has it now to see what's up.

[Maarten]

Your lens is front focussing and quite severely. So please ignore what @Al Brown suggested.

Your explanation of the problem is crystal clear and tech service should have no problem to understand what needs to be done.
When that is not possible (for one reason or the other) they better tell you so you can find an alternative solution, like a sale or trade-in of your lens.

[PhotoCruiser]

Some years ago i bought the 50$ DataColor LensCal device to check lenses for front or back focus.
Some cameras can correct fron/back focus in-camera, Leicas can not 😞
Amazon sells similar device from JJC for about 40$
You can make on for free downloading and printing the many available test charts.
Chris

[PhotoCruiser]

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vor 47 Minuten schrieb Al Brown:

So if your focus is closer to you than to what you focus on, the technical term actually is front focus.

This!

Chris

[Ecar]

Front focus indeed. I'm surprised Leica sent it back with such an obvious issue. Also, the Summarit is not a particularly difficult lens to adjust. I'd insist.