EOS R7 color anomaly in astro photography

[mdphotography]

my first attempts at astro photography and I noticed a pink spot and streak on almost all my shots, regardless of exposure time (2 - 30 sec), iso (100 - 32000) and aperture (f2.8 - f20).  I was able to remove it in post production but was hoping somebody had a technical solution.  You can see it just below center to the right in the example below and it appears in every shot but the "blue hour" ones, regardless of where I pointed the camera.  I was in a pretty dark camp site, but it's possible there was some stray light from one of the other campers.

body: EOS R7

lens: Sigma 18-50mm F2.8 DC DN | C

iso5000 - f/14 - 18mm - 30 sec

[kvbarkley]

Does it happen when you take a "dark frame" - just do an equivalent exposure with the lens cap on.

[mdphotography]

yep - saw it....I think this means I may have a bad lens   😕

at least it's new and still under factory warranty!

[justadude]

That is more likely to be caused by the image sensor, than the lens.

[kvbarkley]

Yeah, often this is when the camera does not compensate properly for the rows of focusing sensors.

[jrhoffman75]

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@mdphotography wrote:

yep - saw it....I think this means I may have a bad lens   😕

at least it's new and still under factory warranty!

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When you take a proper dark frame with the lens cap on no light comes through the lens. 

[mdphotography]

is that a physical issue with the camera body or do just need to finesse the settings a little more?  this was my first attempt at astrophotography so I expect a bit of a learning curve

[kvbarkley]

Contact Canon and discuss it with them.

[justadude · Accepted solution]

I do a lot of astrophotography.  I have since the film days in the 80's.  I've never seen anything like this from settings being off, or even close to this from the settings... especially with it being a perfectly straight horizontal line.  This is very often a sensor issue.  

[mdphotography]

thanks for the advice!