Weird pattern appeared in photos with focus length above 100mm taken by a7rii

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AC02 New Member • Posts: 21
Weird pattern appeared in photos with focus length above 100mm taken by a7rii
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New to DPReview here, because recently I discovered this serious problem and really need some help.

I do a lot of aviation photography, so the photos requires removal of all the dust spots/small objects like tiny birds. What I usually do is just to add clarity and dehaze heavily in Lightroom in order to see those spots, but last year when I got the new a7Rii and 100-400 GM and did a shoot, this is what I discovered:

100-400 GM, ISO 200, 1/800s, f/9.0, 400mm, AF-C(or A, can't remember), Continous shooting(Hi), Compressed RAW, Electronic Front Curtain Shutter On, Live view On, Screenshot from LR

Weird eh? At that time I didn't take it seriously, but It made me recall another pattern appears at 144mm with 24-240 I rented before I got the 140GM:

24-240, ISO 100, 1/640s, f6.3, 144mm, AF-C(or A, can't remember), Continous Shooting(Lo), Compressed RAW, Electronic Front Curtain Shutter On, Live view On, Screenshot from LR

You can see the white arc flare in the corners. The rental company's explanation to me is that because the lens hood of 24-240 does not have flocking. It might be caused by reflection from the hood.

But with more usage of 140GM, I discovered a similar pattern as well:

100-400 GM, ISO 100, 1/800s, f/8.0, 100mm, AF-A, Continous shooting(Hi), Uncompressed RAW, Electronic Front Curtain Shutter On, Live view On, Screenshot from LR

And 140GM does have flocking in the hood, so the explanation by the rental company doesn't make sense.

Then I tried to relate those two patterns together. They seems to be caused by a same reason, because the longer the focus length is, the pattern is more concentrated in the middle.

Check this shot at 240mm with 24-240:

24-240, ISO 100, 1/640s, f/6.3, 240mm, AF-C(or A, can't remember), Continous shooting(Lo), JPEG, Electronic Front Curtain Shutter On, Live View On, Screenshot from LR

The other point I found is the darker region around the circle is divided in 16 symmetrical region, which means it has no relationship to the aperture(although it looks similar).

100-400 GM, ISO 100, 1/1000s, f/8.0, 400mm, AF-C, Continous Shooting(Hi), Uncompressed RAW, Electronic Fronted Curtain Shutter On, Live View On, Screenshot from LR

Because my friend tried my 140GM on his a7rii, I asked him to do a similar adjustment in LR in order to control the variable of body differences. He saw a similar pattern as well:

I searched online and found no similar problem was discovered among Sony users. I guess maybe it is because no one do this kind of heavy post like me? Or I got lucky and got a quality issue?

Both of my 16-35 ZA and VM40 1.4 work fine and don't have this pattern appears in photos. The 24-240 only has this pattern in photos that are taken with focus lengths above 100mm.

I also did some test. The pattern seems to be not related to AF/MF setting, continuous shooting setting, live view setting, aperture setting, or Steadyshot setting. (Or maybe there are some relationships but only occurs in a very specific condition)

Only few of my 140GM photos don't have this pattern, and they're taken in a studio:

100-400 GM, ISO 100, 1/60s, f/16, 100mm, AF-S, Single shooting, Uncompressed RAW, Electronic front shutter On, Live View Off, Taken with Strobes, Screenshot from LR

Hope someone can do some test as well.

Jerry

 AC02's gear list:AC02's gear list
Sony Cyber-shot DSC-RX10 Sony Alpha a7R II Voigtlander 40mm F1.4 Nokton Classic Sony Vario-Tessar T* FE 16-35mm F4 ZA OSS Sony FE 100-400mm F4.5-5.6 +1 more
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