Backfocusing 50mm Summicron v5

[Adalsteinn S.H.]

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Hi there.

 

I acquired a nice M262 body along with a 50mm Summicron v4 for a reasonable amount. The M242 is such a beautiful piece of equipment, weights less than my old MP240.

 

However, the Summicron backfocuses excessively something that the seller insists on not recognizing. I’m on the other side of the country (I live in Iceland) and have therefore not met up with him yet.

 

One thing I noticed when I had a further look at the lens is that it seems that a thin layer of metal has been cut from the ring you can see on the back of the lens. I have a hunch that this might be causing the extreme backfocusing. My theory is that this change had been made to fit another camera and the seller never tried the lens on the M262 before selling it to me.

 

You can see a picture here of the back of the camera where you can see how the ring has been cut a little shorter. https://ibb.co/f9SSuJ

 

Anyone here who knows if this is normal or if this could be the root cause of the backfocusing problem?

 

All the best, Al

[TomB_tx]

This kind of grinding has been normal for years, as each lens cam was ground to match the exact focal length, which varies slightly lens to lens. All my Summicrons (and most others) show the same.

[jdlaing]

Normal. It is on several of mine.

[Ko.Fe.]

If it has same focus shift at all apertures it is not normal.

All non aspherical Crons do focus shift, But they were optimized this way or another.

I had Rigid with focus shift and now v4 this same shaving on RF focus cam.

It is optimized for f2 and close distances. At smaller appertures it focus shifts, but it is compensated by DOF.

[lct]

+1. Sounds like your lens needs some calibration.

[AdamSinger]

I don't know if this helps, with my M10 ,my lenses 50mm and below focused accurately with the range finder, my 1.4 75 F2 90mm and 135 heavily back focused and had to send them back to Wetzlar to get accurate focusing.

Edited July 18, 2018 by AdamSinger

[Ecar]

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Can you rule out camera's RF misadjustment? In other words, do other lenses focus fine on the M262 body? 

[wizard]

Hi Al,

 

The area on your lens which has been ground (and so is shorter than the rest of the ring) is actually the area where the cam follower of any M camera contacts the lens. The cam follower will in normal operation never touch the remaining, non-ground area of the lens. So you may rest assured that this ground area is perfectly normal. However, your lens may still adjustment if it backfocuses badly as you say.

 

Cheers, Andy

Edited July 18, 2018 by wizard

[jaapv]

I suppose this lens has never been modified to use on a digital M. Send it to Leica or a third-party repair person to adjust and code.

[Adalsteinn S.H.]

Thank you all here for your help. I met up with a friend of mine who owns a M240 and we found out that the lens is to blame, not my M262. The lens has been send to Leica for fine tuning. 
 

Now for the long wait. 

[Guest]

On 7/20/2018 at 1:28 AM, Adalsteinn S.H. said:

Thank you all here for your help. I met up with a friend of mine who owns a M240 and we found out that the lens is to blame, not my M262. The lens has been send to Leica for fine tuning. 
 

Now for the long wait. 

Apologies for bringing up an old thread but how long did it take, and was it a significant improvement?

Many  thanks 😀