a7III PDAF striping in practice

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JimKasson
JimKasson Forum Pro • Posts: 19,556
a7III PDAF striping in practice
24

Let's review the bidding.

  1. We have seen images taken with the a7III that show visible striping associated with PDAF pixels in backlit situations with lens flare.
  2. We have several fixes for the striping (eg. Prof Hank, Raw Therapee)
  3. I wrote instrumentation that can find the striping in the raw files, and it finds striping in other a7x (and a9) camera files, with the a9 being one of the most susceptible, right up there with the a7III. But the instrumentation is much more sensitive than we poor humans, so it tends to be alarmist.
  4. Horshack has found, with lens-off testing, that rays far from perpendicular to the sensor tend to cause the most striping.

But we don't know exactly what circumstances cause visible striping in the field, or whether the a7III striping is about the same as the a9's, which doesn't seem to be a problem for almost anyone.

Today the big brown truck delivered an a7III to me, and I can now start to address those issues.

My first experiment was to put a Batis 85 on the a7III, open it up all the way, and put a bright light source in the corner.

Then I applied a brutal curve (and some WB):

This makes the flare form the light more apparent.

I went looking for the striping. I couldn't find it. Can you?

Then I deliberately set up a situation with obviously reflective flare, which, I thought,  might get the ray angles further from perpendicular to the sensor:

The flare is a little hard to see here but just wait.

I hit the above image with another, ahem, aggressive, curve:

Now you can see the reflective flare at about 5 o'clock.

I can't see any striping there, either.

I will start trying other lenses. I do not have the Sony 85/1.8 that RIshi used in earlier tests.

Comments and ideas are welcome.

Jim

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