Pixel Shift artifact with long exposure

JerzyJ · 12-28-2019, 06:01 AM

As I couldn’t find anything about using pixel shift during long exposures and artifacts created by changing light i tried it myself. What I assumed was that changing light will affect colour registered by each pixel in the sensor, so from my camera’s point of view it means movement. I’ve set my camera for 30s exposure with motion correction and was very suprised with the outcome. Part of my shots were covered with lighter or darker stains. After quick check in rawtherapee I’ve found out that almost every pixel was masked as moving. Opening in DCU and switching off motion correction seems to do the job and picture look fine again. „Stains” seemed to be created by motion correction algorythm, so lighter parts were from pixel shift and darker from first frame. Seems that my camera just went a bit crazy after getting so many moving pixels in frame...
So if you are wondering, now you know, and if you just tried it by yourself you may not be as scared as I was

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**sergysergy** · 12-28-2019, 06:10 AM

Yep, I can confirm this. I tried something similar and I could see squares all over the place. Too bad

**SteveinSLC** · 12-28-2019, 01:51 PM

I always just assumed it wouldn't work for long exposures. Either stuff would be moving, or the light would change. Maybe for product photography in a studio where the light can be controlled?

**beachgardener** · 12-28-2019, 02:45 PM

before even trying pixel shift sounds like something that would not be good for long exposures

JerzyJ · 12-28-2019, 03:25 PM

Originally posted by beachgardener

before even trying pixel shift sounds like something that would not be good for long exposures

Not always true, every single long exposure (up to 30s) went good with one condition: motion correction should be disabled. Each shot had a big boost in resolution, no artifacts seen as long as there is no real motion in frame (as grass on a wind), even in changing light conditions. In most cases exposures from 5 to 15s were ok, even with MC on, only few of them resulted with artifacts as mentioned, but there comes the DCU which allows to disable MC in postprocessing.

**swip** · 12-28-2019, 08:53 PM

Very interesting fact. Thank you.

**clickclick** · 12-29-2019, 01:04 PM

Originally posted by JerzyJ

Not always true, every single long exposure (up to 30s) went good with one condition: motion correction should be disabled. Each shot had a big boost in resolution, no artifacts seen as long as there is no real motion in frame (as grass on a wind), even in changing light conditions. In most cases exposures from 5 to 15s were ok, even with MC on, only few of them resulted with artifacts as mentioned, but there comes the DCU which allows to disable MC in postprocessing.

Interesting that MC off worked better. Good to know.

JerzyJ · 12-29-2019, 02:46 PM

Originally posted by clickclick

Interesting that MC off worked better. Good to know.

That’s for K1 mkII, on my K70 artifacts realted to movement are more severe, with a lot of green and yellow fringing, so it may look a lot worse in this scenario... I’ll chceck that some day.

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12-28-2019, 06:10 AM	#2
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,170	Yep, I can confirm this. I tried something similar and I could see squares all over the place. Too bad

12-28-2019, 01:51 PM	#3
SteveinSLC Site Supporter Join Date: Mar 2017 Photos: Gallery \| Albums Posts: 568	I always just assumed it wouldn't work for long exposures. Either stuff would be moving, or the light would change. Maybe for product photography in a studio where the light can be controlled?

12-28-2019, 02:45 PM	#4
beachgardener Site Supporter Join Date: Sep 2013 Location: Australia Photos: Gallery Posts: 3,842	before even trying pixel shift sounds like something that would not be good for long exposures

12-28-2019, 03:25 PM	#5
JerzyJ Junior Member Join Date: Mar 2019 Posts: 33 Original Poster	Originally posted by beachgardener before even trying pixel shift sounds like something that would not be good for long exposures Not always true, every single long exposure (up to 30s) went good with one condition: motion correction should be disabled. Each shot had a big boost in resolution, no artifacts seen as long as there is no real motion in frame (as grass on a wind), even in changing light conditions. In most cases exposures from 5 to 15s were ok, even with MC on, only few of them resulted with artifacts as mentioned, but there comes the DCU which allows to disable MC in postprocessing.

12-28-2019, 08:53 PM	#6
swip Site Supporter Join Date: Sep 2011 Location: Ottawa, Ontario Photos: Gallery Posts: 2,825	Very interesting fact. Thank you.

12-29-2019, 01:04 PM	#7
clickclick Loyal Site Supporter Join Date: May 2016 Location: East Coast Posts: 2,903	Originally posted by JerzyJ Not always true, every single long exposure (up to 30s) went good with one condition: motion correction should be disabled. Each shot had a big boost in resolution, no artifacts seen as long as there is no real motion in frame (as grass on a wind), even in changing light conditions. In most cases exposures from 5 to 15s were ok, even with MC on, only few of them resulted with artifacts as mentioned, but there comes the DCU which allows to disable MC in postprocessing. Interesting that MC off worked better. Good to know.

12-29-2019, 02:46 PM	#8
JerzyJ Junior Member Join Date: Mar 2019 Posts: 33 Original Poster	Originally posted by clickclick Interesting that MC off worked better. Good to know. That’s for K1 mkII, on my K70 artifacts realted to movement are more severe, with a lot of green and yellow fringing, so it may look a lot worse in this scenario... I’ll chceck that some day.