a7x, a9 PDAF stripe noise technical analysis, part deux

Started 10 months ago | Discussions thread
Horshack Veteran Member • Posts: 7,003
Re: Off the backboard

ProfHankD wrote:

Horshack wrote:

ProfHankD wrote:

Horshack wrote:

I didn't have much time today to work on this but I wanted to get a no-lens G1 reflection, which required vertically angling the camera at greater than 45 degrees and then bouncing the light off the lens mount.

I just tried pretty much the same thing with my A7... and here's what I got:

The lines are there, but they're darker than the background, not brighter!

That's true for every one of a bunch of test shots done with a bright LED flashlight pointed at various odd angles relative to the open mount of my A7.

Not sure what this means. Should I be having KARWY-SR recognize and repair either brighter or darker lines, or is it virtually impossible for the darker lines to occur with a lens mounted?

Can the same sensor produce both brighter and darker lines or is this a per-sensor phenomenon?

Can you PM me that raw? Thanks!

I'll do better than that; I've put the raw up openly accessible at:


BTW, if you're trying to view it in RawTherapee, it's most visible doing "mono demosaicing" where it shows as slightly darker lines.

I should also add that I'm pretty sure the dark splotches mean it's time to clean the sensor -- i.e., I think they're just dust shadows drawn out by the extreme lighting angle.

Thanks. Took a while for the raw to download but I got it. All of  your A7 striping is two pixels wide and is indeed shaded instead of brightened. More importantly, the striping is in the red channel exclusively, which implies the PDAF are arranged over different pixels on the A7, which dovetails with a recent tech article saying Sony switched to a different pixel CFA position after their earlier PDAF implementations.

Btw, I have seen shading instead of brightening on the A7rII but only in the magic raw.

Something just occurred to me that has me seriously reconsidering the original reflection theory again. I'll post it shortly. Thanks Hank!

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