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Pixel artifacts on long exposures

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I did a long exposure last weekend for star trails and while it looks nice I cannot use it because it is full of these colorful artifacts.  On different long exposures they appear in similar areas.  They also appear on my X-T1 sometimes.  I have had the sensor cleaned for dust at a camera shop on both cameras.



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Interesting pattern.


I don’t think this is a stripe of dead or hot pixels.


The enlargement of the first portion shows things that could be hot pixel but other things that are not globular and most certainly some form of “ dust” .


What is the luminous object crossing he image in a wavy line?

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Was dark frame subtraction enabled?


Color artifacts usually appear in Lightroom, I remember that the artifacts looked gray in SOOC JPEGs. Of course, I reported this phenomenon in late 2015 when I tested the X-Pro2 in Hawaii, so I was surprised to read about it from a few users with production models later in 2016.


Since Fujifilm made changes in the dark frame subtraction of the X-T2 (processing now sometimes takes longer than taking the actual long exposure), I assumed that current X-Pro2 firmware should be okay, too. Especially since this topic rarely (if ever) pops up these days.


As for the source of the problem, I tend to assume sensor (over)heating is the culprit. That said, if dark frame subtraction doesn't help, I'd have the camera serviced. 

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This is from a very long exposure, 3550 seconds (10-24mm @10mm, f11, ISO 200).  I didn't do dark frame subtraction but had Noise Reduction turned on.  I did another long exposure of about 210 30-second exposures (10-24mm @10mm, f4, ISO 800) and am working on processing those (Noise Reduction turned off).  First appearances show that there are much less artifacts, tho a few are there.  Much easier to fix.  What is your favorite way to process star trails?  I'm currently toying with StarStax


The wavy line is someone walking in front of the camera with a headlamp.


Enlargement of one of the newer exposures below.  This is just mountain, no stars. 

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Edited by fxfesev
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