#185. A spotty flaw in the Zeiss FE 35/2.8 ZA & Sony A7r combo ?

By pascaljappy | Review

Dec 11
[Note : This post is part of the ongoing review of the Sony A7r system]

Shooting at low apertures against the produces sun stars that can add a lot to some pictures. The more open the diaphragm, the more blurry (scattered around the frame) the sun’s diffraction patter. Conversely, the less open the diaphragm, the better individual rays appear. 2 for every blade in the diaphragm.

But there seems to be a limit with the Sony A7r & Sony Zeiss FE Sonnar 2,8/35 ZA, as illustrated in the photograph below 🙁

Spotted reflections ?

Spotted reflections ?

The sun rays are there all right, prolonged by a play of light and shadows in mist produced by the sun’s heat on the morning frost. But so is an unwanted battalion of “spots” surrounding the sun in a geometrical pattern, shown here in high contrast.

I can only imagine the increased depth of field at f/20 has picked up reflections of the sun on the sensor ???

Whatever the reason, this is going to be a post-processing nightmare, if I can get rid of them at all …

It wouldn’t be so bad if these spots only appeared at f/20, but they are plainly visible, although in a more diffused manner at much more mundane apertures, such as f/11. See below, original jpeg :

Sun spots of a new kind ...

Sun spots of a new kind …

This one could be saved with a panoramic crop, but still, there’s a major (coating ?) problem that will pester all those fans of sun stars (probably astronomy fas as well) …

Note that these two pictures also display what Leica Boss called the bullseye colour shift (explanations on how to cure that are in the article).
Any clues ? Sony, perhaps ?

Crop da spots

Crop da spots

  • […] Pascal: “I tested low and high iso noise & noise reduction with long exposures. Also vibrations and a sidenote on coma (largely absent) in the Sonnar Lens. http://dearsusans.wordpress.com/2013/12/12/186-low-light-long-exposures-with-the-sony-a7r/” And: “there is a reflection problem with the A7r / Sonnar 35/2.8 ZA that produces spots around bright lights. It isn’t the bullseye colour shift reported by Leica Boss but something else. I wrote a quick piece here about it : http://dearsusans.wordpress.com/2013/12/11/spotty-flaw-in-zeiss-fe-35-28-za-sony-a7r-combo/” […]

  • Rich says:

    Yawn.
    Just don’t shoot into the sun…

  • Mark Hammon says:

    I wonder if this is the result of a rear element that is much closer to the sensor then you would normally find in a DSLR? The light reflecting off the sensor (no antialiasing filter may make this worse??) and hitting the rear element and reflecting back. This happens in all cameras, but the short distance of the Sonnar lens and maybe a more reflective sensor might amplify it. This is just speculation. I have yet to see this, but I have not shot this kind of shot yet. Interesting post.

  • Sim Hung Ho says:

    It doesn’t really matter what the problem is. Just work around it. Every camera has flaws. Perfection is reserved for the gods.

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