Question regarding infinity focus on 50Lux

[humerc]

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I have a strange behavior of my 50 Lux ASPH:

If I set it on infinity on my M10D it works as it should - I can align the rangefinder with the subject. Also my 28 Lux and 35 Cron work flawlessly on my M10-D.

On my MP (Film) the 28 Lux and 35 Cron also work as expected - but the 50 Lux cant be aligned on further away objects (but the same object with the same lens on the M10-D aligns) - it stops a bit before it should stop.

Can anybody tell me what that could be? Why is this only a problem of 1 out of 3 lenses at only 1 of the cameras? And why do all 3 lenses on the other camera work as expected? If the camera has a fault - shouldn't that be a problem with all 3 lenses? And if the lens has a fault - shouldn't it be a problem on all 2 cameras?

Help would be much appreciated - thx

Edited May 18, 2021 by humerc

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[stallus]

Hello,

It is hard to tell, where the problem comes from.
Questions: regardless of aligned or not aligned rangefinder patchfield, are the pictures ok when focused at infinity subjects(focus is at hard infinity stop) ?
For the film MP this is maybe not instantly testable, or do you have developed pictures with known settings regarding focus?

Maybe you can check the patch alignment with an artifical infinity target at home: 2 objects (cross or x) on a paper with a distance of exactly 69,25mm (rangefinder base)
If you align the 2 objects , the lens shall be at infinity.

regards

Reiner

 

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[humerc]

Thanks Reiner!

I cant be sure at my film photos if they where shot at infinity (and also I dont always remember the lens)

I just checked the 50 Lux and the 28 Lux on the M10-D - both align correctly in the rangefinder patch and also the photos look sharp (no scientifically testing).

On the Film MP if I move the 28 Lux to infinity the object aligns like on the M10-D.

If I try this with the 50 Lux on the MP and set it to infinity on the same object - the rangefinder patch doesn't align, it stops (remarkable) before I reach the object.

(I tried your suggestion with the cross on a sheet of paper - but it look like I am to stupid to get that done...)

 

Edit: After a few tries I figured your "artificial infinity target" test out - and it looks good on both - the digital and the analog M. - thanks for the tip!

 

But in real life I still have the problem with the 50 Lux not aligning infinity objects at infinity at the analog M. I will try a few test with the moon tonight (if visible).

Edited May 18, 2021 by humerc

[a.noctilux]

Hello Hemerc,

How "far" is the discrepency, at infinity, taking the MP's  RF patch width as 10 units ?

In which way ?

[humerc]

It stops before it reaches infinity - I would guess at about 10-15% of the width of the small rangefinder patch.

Edited May 18, 2021 by humerc

[a.noctilux]

So not much, really.

In my long use of Leica M, film use the 1/10th of discrepency would not impact the results, mainly in long distance.

For peace of mind in the past, I would take the camera to repair shop then wait for the mild adjustment.

 

But time changed, I would use without fear and try to live with this if I use fast film (my norm bynow).

 

To go further, can you try out at close distance, 1m then 2m, comparing the focus of your two Ms with the Summilux 50mm.

Edited May 18, 2021 by a.noctilux

[humerc]

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Sure, will try different distances on the weekend (and develop a roll to check).

It isn’t  be a big problem for me if I know it doesn't affect the photos - but it is strange that its only with one lens/camera combination and the same lens works on another camera - and other lenses work also - on both cameras, I just don’t understand it, as it is not logically to me. Normally I would say that also the other lenses should have problems on the MP.

[a.noctilux]

Simple explanation is "tolerance", why I asked you how much discrepency.

Anecdote, some years ago, I had same problem as you here, when I went for adjustment, the repair man showed me how he did it with Standards.

Adjustments for lens+camera only can lead to "errors" when we change lens or camera.

He talked about tolerance in adjustments and acceptable errors and mostly consequence in results which is the most important.

 

Here, I think it's small error on lens focus mechanism in opposite sign with the camera mechanism, but maybe in tolerances with both elements.