Issue with APO Summicron 90

[ianman]

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I don't use the lens very much in these conditions so I've never noticed this issue. Maybe it's been there all along but I've never noticed it before.

The "eye" is always looking towards the center of the image, so the closer it is to the center, the more it looks like a fried egg !

 

Does anyone know what's going on here ?

 

 

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Another example

 

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[01af]

Maybe there's a speck on one of the internal lens elements, close to the diaphragm. Dust, dirt, and specks on the outer surfaces of the front or rear element usually won't show up in the pictures. But when it's in or near the plane of the diaphragm then it may possibly give effects like those seen in the pictures above.

[ianman]

Thanks!

I can't see anything... maybe time for a CLA... hopefully it can be cleaned inside?

[jaeger]

did you buy your lens used?  I guess Leica can fix it if it's under warranty.

 

Thanks!

I can't see anything... maybe time for a CLA... hopefully it can be cleaned inside?

[adan]

"Onion-ring bokeh" from the 90 APO's press-molded ASPH element.

 

https://www.imaging-resource.com/news/2014/05/02/the-end-of-onion-ring-bokeh-panasonic-beats-the-curse-of-aspheric-lenses

 

With luck, once Leica does their next revision of the 90 APO (now a 20-year-old product) they will leverage their technology partnership with Panasonic to improve their ASPH molds.

Edited April 18, 2018 by adan

[ianman]

Thanks Andy! It's strange that I'd never noticed - or even heard about - this before. Of course, now I know, I'm seeing it everywhere!! But these two examples are quite extreme.

[ianman]

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did you buy your lens used?  I guess Leica can fix it if it's under warranty.

 

No. I got it secondhand 9 years ago... all the more embarrassing that I've never seen it before. But like it I wrote, I don't use it in such conditions often, or ever really, and I'm not a pixel peeper. It's just that in these photos, the effect is unmissable!

[mmradman]

Summilux M 50mm ASPH, APO Summicron M90mm ASPH, also APO Summicron M 50mm ASPH all three in my hands exhibit “onion rings” discussed and well known phenomenon with, you guessed it, ASPH lenses.

 

One of advantages of vintage lenses like Leica R providing not ASPH like APO Summicron R 90mm. As a counter to latest crop of M and L primes, all ASPH, I have purchased Zeiss ZF.2 APO Sonnar 2/135mm which is spherical design, trait shared with Leicas finest R APO and non APO lenses.

 

If any current L lens is onion ring free than Panasonic is behind.

Edited April 18, 2018 by mmradman

[adan]

Thanks Andy! It's strange that I'd never noticed - or even heard about - this before. Of course, now I know, I'm seeing it everywhere!! But these two examples are quite extreme.

 

Bokeh for a given lens varies with scene contrast, and the relative distances to the in-focus and out-of-focus planes, and other things. Because of the ways the light rays criss-cross in different focusing settings, and how tonally-separated such things as the bright/dark onion rings are reproduced (note the difference between your first and second examples, for example). And of course the aperture setting (which has implications for both how big and how "sharp" the effect is). So it's not surprising it isn't always this visible or noticable.

Edited April 19, 2018 by adan

[Herr Barnack]

I have a 90 Summicron APO that I bought new in 2003 but don't recall ever seeing it produce onion ring bokeh.  Ianman's example images are backlit, which makes me wonder if the onion ring bokeh occurs only (or mostly) when photographing a strongly backlit subject.

 

Can anyone shed some light on this? 

[adan]

I would think only to the extent that in this case, the backlighting contributes to the subject contrast range (white backlit flower against inky black tree trunk and forest, with blurs from pinprick light sources (individual forest leaves or gaps showing the sky).

 

Same flower against a bright field and sky (still backlit) might show nothing, or substantially less.

[spydrxx]

I noticed the same phenomenon a few weeks ago as I was photographing (with non-Leica lenses) some cameras to put up for sale. By further closing down the diaphragm the issue disappeared.