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Bad Dark Files, artifact, error (and in some Light frames)

DuteNait
07 Jun, 2019 04:54
I noticed with some Dark files that they have a strange artifact. It looks like Light leaks in from somewhere, but it is consistent. It doesn't matter if I take them in Pitch black or with different Objectives. But it doesn't happen all the time. Also, some Light frames with high ISO have the same Issue. The final Light frames with longer exposure, and lower ISO don´'t have it. Why does it happen with Dark frames with the same acquisition Time and ISO.

Dark Frame with Artifact
120s, Iso 800
Light Frame with Artifact
30s, Iso 6400

Both are stretched a bit.
Camera: Canon 600D Full Spectrum Modification
Edited 07 Jun, 2019 04:55
glennb44
08 Jun, 2019 09:11
Its not like amp glow and if its not stray light from the image train or from the viewfinder, then maybe its a fault from internally defective modification?

GlennB
DuteNait
08 Jun, 2019 12:56
I'm not sure how the modification could affect it. Im sure that it is'nt light leak from the objective side. But maybe from the viewfinder.
I had the idea that it might be from the internal dust removal but this shouldn't alter the raw file, and this function was never used or has data.
I'm confused that it doesn't happen all the time and only some darks and lights are affected.
astroCH
08 Jun, 2019 22:09
Hi, as I'm using the same  modded DSLR like you, I try to understand what happened here… I've never had such an issue with my files smile  and I cannot imagine that replacing filters inside the body would have change something. Did you try taking a few darks with simply the plastic body cap mounted, I mean no lens attached ? Give it a try in a dark room (…or in your fridge if you need darks at 6-8°C ;-) and look what happen to your data. Do you have any light source next to your dslr while imaging? Remote control with pulsating lights? Autoguider? Front self-timer lamp on? smile
Christophe
glennb44
09 Jun, 2019 05:17
I saw a pic showing a mod where some light pathway was inadvertently created - some proximity to a LED that wasnt usually there.   Cant find that URL now of course. I'll keep looking…

GlennB
DuteNait
09 Jun, 2019 09:19
Thanks for all your Help. I got some wierd artifacts again last night. I try it out today and no artifacts, just laying on my bed. So it isn't the view finder or other outside light, there were much more light now then yesterday. I don't have a bodycap right now, but im going to try it out.
If there is an led, It isn't the selftimer lamp, it wasn't on or the battery indicator lamp wich was on today and caused no artifact. It may be a reflection on the inside element or the mirror. Is there an IR led wich wouldn' cause problems with the filter?
I'm totally confused by this inconsistency.
 
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