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Friends of high resolution full frame images,

since I consider myself as only mediocraly successful in the "birds in flight" benchmark category so far, I resorted to trying out "insects in flight" which are also animated objects, but give you the benefit of a significantly higher trial frequency as such:  =8-)

The arrival of insects is actually hard to predict, while their departure is pretty much predictable, if you observe their location for an extended period of time. 

I tried a "freeze" of motion, even for the wing movement, by setting the time priority at 1/10.000th or less.

And this is what I discovered:

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At full scale, this looks pretty much OK, I would presume. But zoomed in, some serious and interesting artifacts become visible,:

>>> see next post, because of upload file size limit ...

 

Edited by Chrissie
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Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Note the horizontal banding in the wings of this insect.

This is a cut-out of the original image.

Taken at ISO 3200, 1/16.000th, f5.6, 400mm , sel100400GM

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Based on your shutter speed I presume this was shot with an A9? Your post doesn't say, I was confused a bit by your opening sentence which seemed to refer to an A7Rx photo.

I think it has to do with the electronic/rolling shutter of the A9: it reads about 5 rows of pixels at once and then proceeds with the next 5 rows. The wing of the bumblebee will have moved a bit in between the two read sequences, causing the banding you see. Even though your exposure time was 1/16000 sec, reading the entire sensor takes about 1/200 sec. The sensor readout thus takes much longer than the actual exposure time.This also causes banding in extremely high frequency LED-lighting for example. Try the mechanical shutter at 1/8000 sec and see if the banding persists. Perhaps also disable EFCS, tho I doubt this has anything to do with it.

Edited by Pieter
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Thanks, guys, for your feedback.

@Pieter: yes, it was shot with an a9 - sorry for not mentioning. I was also using drive mode set to "Hi", and by the sound of the camera I would assume it was actually operating at 20 fps. I don't see this in the exif, though. Which would leave only 50 ms per each full sensor readout. And this was shot in bright sunlight - no artificial light involved. I will try out the mechanical shutter, as you suggested.

@LiveShots: yes, this is the range which I also found, even though you probably meant to say "beats per second".

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A full sensor readout takes about 5 ms (1/200 sec) so there's some spare time between shots. Assuming the sensor is read in 800 row pairs, the time between two pairs of rows being read is about 6 ns. Only very fast moving subjects or extremely high frequency artificial light will cause issues with the A9, visible as banding on pixel level.

I can see it wasn't shot under artificial light, just saying that this may cause a similar issue (though will look very different).

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Here you go, seems like I was wrong on a couple of parameter magnitudes as I did it from memory but the principle for the cause of your banding still stands:

Sensor is read in 12 rows at once (not 5):

http://blog.kasson.com/the-last-word/sony-a9-electronic-shutter-operation-single-shot/

Mechanical shutter closes at 1/300 sec, the electronic shutter at 1/150 sec:

https://blog.kasson.com/the-last-word/how-fast-is-the-sony-a9-electronic-shutter/

As an engineer I'm sure you'll appreciate Jim Kassons crazy elaborate testing and documenting ?

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