a7x, a9 PDAF stripe noise technical analysis, part deux

Started 7 months ago | Discussions thread
ProfHankD
ProfHankD Veteran Member • Posts: 6,167
These aren't the stripes we're looking for.

I got the bright idea (and bad pun) of trying to get the stripes in the sensor reflection that my Tamron 52B SP 90mm f/2.5 macro likes to give when photographing strongly backlit things.  So, I stuck the Tamron on my A7 and this lovely model in my lightbox:

Horizontal lines! Big fat stripes!  Wait. Fat?

Shutter speed of 1/500s with LED lights using a variable-brightness controller that probably has the lights flickering. Shots at different shutter speeds have different width lines. Drat.

So, I still haven't gotten my A7 to show the stripe defect, have I? Other Sonys that haven't produced good stripe artifact images in my tests yet (at least a couple dozen test scenes each):

  • NEX-7: no PDAF, so no surprise here?
  • A7
  • A7II

Thus far, these are the stripes we're looking for:

  • RX100-V: moderate stripes, easy to get
  • A6000: heavy stripes, easy to get
  • A6500: light stripes, easy to get
  • A7RII: heavy stripes, very hard to get

I'm posting sample images at http://aggregate.org/DIT/KARWY-SR/images.html

My most reliable test scene is a halogen lamp photographed with a Sony A-mount Samyang 85mm f/1.4 lens wide open on an LA-EA3 adapter. This lens has big front and rear elements that should allow more diverse light angles, but it also has really excellent coatings, so it doesn't flare very easily.

 ProfHankD's gear list:ProfHankD's gear list
Canon PowerShot SX530 Olympus TG-860 Sony Alpha a7R II Canon EOS 5D Mark IV Sony a6500 +30 more
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