Apo Summicron 75mm Focusing Problem

[Cobram]

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On 5/12/2020 at 1:43 PM, Stein K S said:

Just one more technical question. Do you always need to tap to make it work... or do you also experience a difference whether you focus in on the object clockwise (from infinity) or against the clock (from closer distance)? Still a problem since fine tuning always is needed, but I am curious about how the inside of this lens behaves. Will also make some testing myself.

Do you still own the Summicron 75 or you purchased Summarit again?

I experience similar focusing problems resulting in almost no keeper from my daughter musical performance - frustrating lens (my copy).

[anonymoose]

Resurrecting an old thread here as I just purchased an APO-Summicron-M 75mm. There's something wrong with how light is getting focused at f2. It cleans up significantly at f2.8 and above, but at f2 something is clearly going awry. I set focus on the little bush using the RF and Live View and here's how the image came out (this is about 200% zoom) at f2 and f2.8

It almost seems like it's front-focusing at f2 even though RF/Live View show the focus being exactly where I want. Then when I shift to f2.8 and higher the focal plane ends up where it's supposed to be. Not sure if that's even physically possible?

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Edited February 4 by anonymoose

[wlaidlaw]

I had a similar problem with my 0.95 50 Noctilux, when new. I could not believe how far out of focus it was. I christened the Leica technician who signed off on the QC card, Mr. Magoo (I see no wabbits). It was also aperture shifting very badly, which is exactly what its floating lens element (FLE) was supposed to minimise if not wholly cure. I arranged for a Leica pick up via UPS to return to Solms and it came back some three weeks later totally cured for both faults. I suggest you return the lens if new to Wetzlar or if second hand to the seller, as not being of merchantable quality. There will always be another and almost certainly better lens available. 

Wilson

[anonymoose]

3 minutes ago, wlaidlaw said:

I had a similar problem with my 0.95 50 Noctilux, when new. I could not believe how far out of focus it was. I christened the Leica technician who signed off on the QC card, Mr. Magoo (I see no wabbits). It was also aperture shifting very badly, which is exactly what its floating lens element (FLE) was supposed to minimise if not wholly cure. I arranged for a Leica pick up via UPS to return to Solms and it came back some three weeks later totally cured for both faults. I suggest you return the lens if new to Wetzlar or if second hand to the seller, as not being of merchantable quality. There will always be another and almost certainly better lens available. 

Wilson

Thanks for the comment--very helpful! I'll be sending this back to the store I purchased it from. They fortunately have another one, so hopefully that one doesn't have issues as I really like the size and optical character of this lens...at least at f2.8 and higher