Image from the Star Eater Petition which asks Sony to fix the issue
David Kilpatrick from Photoclubalpha tested the Sony A7RIII pixel shift with a vintage Takumar lens. The conclusion:
Multi-shot pixel shift images, though only 120MB uncompressed, are so detailed that some won’t compress much at all. I have only ever seen this before from medium format, and that includes the Extra Fine single shot regular files.
And Jim Kasson found a Sony a7RII star-eater workaround:
The good news: The a7RII star-eating spatial filtering that takes place at 4 seconds and longer exposures does not occur in continuous low or continuous high shutter modes.
The bad news is that you have to put up with a little more noise and 12-bit precision. As bad news goes, that’s pretty good. The increase in noise is small, and the read noise at ISO 640 provides sufficient dither that you won’t miss those missing bits (at higher ISOs there will be even more read noise, and the increaded noise from the 12-bit conversions will be less significant). There is some question about what that horizontal periodicity means for astrophotography, and I would be interested in hearing from people who use this workaround on real stars.
Join the A7rIII facebook group to discuss the camera features and tests.