Softness - both edges?

[Jon Warwick]

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I have a 50mm f2 non-apo summicron. Purchased new in 2002. Very well looked after.

 

It's not a problem for many images (by getting lost in the bokeh) but for things like landscapes or architecture it is noticeable especially with high res digital cameras and with large drum scanned images.

 

The issue? Imagine I've taken an image of a mountain landscape. The precise middle at infinity focus is tack sharp. But both edges (from top to bottom) of the image in landscape format have drifted into a softer / slight out of focus. In a given image, I'd say 10-15% of the image is softer on each side. This seems across many apertures and for some I'm definitely stopped down to f5.6 or f8.

 

Is this normal for this specific Summicron lens? Or is my lens a dud ? (ie, should I expect it to be fully sharp across the image width?) If there is a prob, what could the issue be?

[NJH]

No I got the same with an Elmar-M stopped down, Fuji Acros scanned on my KM5400. Its tack sharp in the centre but is a touch softer and less contrast outside the central third or so.

 

Erwin Puts reckoned the Zeiss Planar had better field flatness which is surprising as I noticed mine was definitely softer away from the centre on even the M8, the guys at RobertWhite's reckoned I was seeing field curvature which seemed to me contrary to what mr Puts was saying but if I stopped down to F8 and beyond diffraction starts to dull things anyway.

 

How much does this actually matter in practice, I mean by that is it limiting how big you can print? For me I felt that whilst I can see it pixel peeping a 5400 dpi scan from the Elmar-M its not enough of an effect to cause me to think its a problem worth bothering about.

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[spydrxx]

Puts suggested that the extreme edges at about f5.6 might show a slight loss of contrast when compared to the central zone at high magnification, but not drifting off to to softness. It sounds like your particular lens isn't a dud by any means, but perhaps better described as a sample variation showing the more traditional Summicron 50 fingerprint.

[tobey bilek]

There is something wrong with it . Decentering perhaps.

 

Always the possibility the sensor is not positioned correctly. Check with a second lens or second camera.

[luigi bertolotti]

It is NOT normal, expecially in one situation you quote (infinity focusing, not wide open) ; just a question : you said you bought the in 2002... has it been always like this ?

[Jon Warwick]

; just a question : you said you bought the in 2002... has it been always like this ?

 

Not sure, but I'd guess yes. It became very apparent when I started to get "digital", ie, drum scans done off M7 film images, and then VERY apparent in images of landscapes off the M240.

 

If it is decentering, any rough idea how much Leica would charge to hopefully perfect it?

 

It is also non 6-bit (I manually put that data in the settings), so might get that done at the same time.

Edited January 1, 2015 by Jon Warwick

[Jon Warwick]

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I've looked at more images with my 50mm f2 Summicron ..... i'm more certain now that something is not right. It's pin sharp in the middle of an image, but quickly goes slightly off focus around that (fairly small) area. Any idea how much Leica might charge to fix?

 

I also compared it to the images that I took in the past via Leica Mayfair with their 35mm Lux FLE and with their 50mm Lux. Those were generally pin sharp right to the VERY edge of the frame, making me more confident that something is wrong with my 50mm Summicron.

 

What i also realised is that the pop and rendering of those more modern Lux Asph lenses really is BEAUTIFUL. I think they work better than the 50mm Summicron on digital .... they were pin sharp but almost more "cinematic" than what i currently use.