Strange "Blur" Using R7 with RF 100-400 Lens

[danfaz]

Hey everyone, was wondering if anybody knew what might cause this weird "blurring"?
This is a snip of a RAW file zoomed to 100%. Using an R7 with RF 100-400 lens, fully electronic shutter.
When I edit this photo, the effect is more pronounced, almost looking like multiple lines, or ghosting.
This only seems to happen on the blurry parts of the bird.
Could the electronic shutter be causing this?

 

[becceric]

My first thought is motion blur which is more noticeable at wing tip because they move more distance than portion closer to the bird’s body. If focus is on the head/body and wingtips are slightly out of focus, this result would be more pronounced.

 

[EricN]

I think part of the problem what @becceric said, but I don't think it explains the lines

 

[Maximilian]

My first thought is motion blur which is more noticeable at wing tip because they move more distance than portion closer to the bird’s body. If focus is on the head/body and wingtips are slightly out of focus, this result would be more pronounced.

Same thought here.
Even though it is a quite big bird and the shutter was at 1/2000 I think this could happen during wing beating.
-> higher shutter speed could help
If it also appears during gliding, then that would get me puzzled.

 

[koenkooi]

The R7 has a very, very slow readout, around 1/30s for the full sensor and it has IBIS which sometimes moves the sensor in a direction that makes the rolling shutter worse.

Increasing the shutter speed has no effect on rolling shutter, but it might make the effect you're seeing less prominent.

 

[danfaz]

The R7 has a very, very slow readout, around 1/30s for the full sensor and it has IBIS which sometimes moves the sensor in a direction that makes the rolling shutter worse.

Increasing the shutter speed has no effect on rolling shutter, but it might make the effect you're seeing less prominent.

Thanks, makes sense!