Strange bars in a bottom right corner of pics from EOS 6D

[Vroobel]

Hi,

I have a Canon EOS 6D Mk I camera that I bought as used from a professional camera seller with a 12 month warranty, so I think it was a good deal. Since the beginning I have had some problems with dark bars in the bottom right corner of the pictures and they are unable to be removed, even if I also do a set of 20 or 50 calibration frames. In the meantime I ordered an astro modification at one of the local specialists. I still see the unwanted effect, so I mention the modification to exclude the case that it happened just because of the operation. I place two highly stretched raw stacks of the M81 and M82 obtained with the IDAS LPS-P2 filter and also the M45 without any filter to exclude the suspicion that it can be caused by some filters. Accidentally you can see a gradient, but it's not related to any gradient, because I experienced it in different conditions.

I hope someone can explain why it happens and how to cope with it.

Best regards,
Vroobel  

Edited November 8, 2022 by Vroobel

[michael8554]

Hi Vroobel

I have a modded 6D and I don't have that light gradient on my images.

Have you blanked off the viewfinder aperture with the rubber thingy you may find on the shoulder strap ?

To prevent extraneous light marring your images.

Michael

[Vroobel]

Hi Michael,

Yes, my viewfinder is covered. 

I dont't complain about the gradient. I asked for a cause of the dark bars in the bottom. 

Tomasz.

Edited November 9, 2022 by Vroobel

[Carbon Brush]

Is this problem only seen on long exposures? Is daylight use OK?
If so, might there be stray light getting in somewhere else?
A crack in the case? Missing screw?
Wrapping the camera in something opaque at night might help you. Even if it is insulating tape. Anything lightproof.

Or is there an LED somewhere in/on the camera that is working and stray light finds its way to the sensor?
There are options on Canon camreas to tourn off indicators. I don't know the details for the 6D.

Or is it a degrading sensor?

Or I may be barking up completely the wrong tree🙄

[Vroobel]

Oho, lot of questions!

5 hours ago, Carbon Brush said:

Is this problem only seen on long exposures? Is daylight use OK?

Honestly, I don't know. I just checked, it seems similar regardles the exposition time (60s, 150s, 300s), but I think it's more visible with stronger stretching. And I don't remember whether I took photos shorter than 60s.

5 hours ago, Carbon Brush said:

If so, might there be stray light getting in somewhere else?

I don't think so. It happens both with no filter at all and with filters LPS: IDAS LPS-D2 and IDAS LPS-P2 and also dual band Opiolong L-eXtreme. The last one especially should cut out all unwanted light.  

5 hours ago, Carbon Brush said:

A crack in the case? Missing screw?

Hmm, I didn't realise any. Moreover, When I sent the camera to astro modification, I had a question about its condition. I replied that it's in very good used condition. I have bought it from a professional seller as used with a 12 month warranty, so they would risk a lot if they sell faulty camera for nearly 500£. Regarding the missing screw, I think I would know about it if it happened, from the man who modified the camera.

5 hours ago, Carbon Brush said:

Wrapping the camera in something opaque at night might help you. Even if it is insulating tape. Anything lightproof.

That's interesting approach. Thanks for the idea!  

5 hours ago, Carbon Brush said:

Or is there an LED somewhere in/on the camera that is working and stray light finds its way to the sensor?
There are options on Canon camreas to tourn off indicators. I don't know the details for the 6D.

No, it isn't. That means there is a red LED indicating (as I think) saving the image to the memory card. It's off during the exposition. Also the viewfinder is black at all, only displaying some values when the camera begins saving data.
I'm not sure, but I think I already switched the indicators off.  

5 hours ago, Carbon Brush said:

Or is it a degrading sensor?

What do you mean?  

I have no Canon or compatible lens, I have bought the body only just as a full frame sensor for astrophotography, so I cannot compare and check it in other ways.

My conclusion is that it's more visible with stronger post processing. This is a complicated subject. My home-made EQ fork mount still requires some improvements. I can obtain nice pics, but I think the signal is low because of poor guiding. I work on it and have some ideas, so we'll see very soon. Sey stars, they are not pinpoint, but like small disks or more often ovals. The worse the guiding is, the more oval they are. I suspect that improving the guiding would significantly limit the need of strong stretching, am I right? Maybe then the bars are less visible?

Vroobel

Edit.
I forgot to mention that the bars are rather dark on a lighter background - the gradient makes them visible. But after use of the GradientXterminator the bars are also visible. Why are they dark? If it's an effect of unwanted light they should be bright.  

 

 

Edited November 9, 2022 by Vroobel