Vertical bands - Source? Solution?

[cmassa]

I was stacking part of mosaic which included 30 x 10 min lights at iso800 with darks, flats, bias frames. When looking at the integrated light frame I noticed vertical stripes. I have not had that before. When I looked at all of the light frames with the blink tool I did not seen any there. I looked at my prior image, it was not there. Any ideas where they came from or how to get rid of them?

Thanks,
Chris

[TobiasLindemann]

Hi Chris,
IMO it looks like the lights are not calibrated right.
Maybe the temperature of your darks or biases don´t match the lights, or you haven´t made enough biases. You should stack >100 biases, or use the "superbias-process" http://pixinsight.com/forum/index.php?topic=7266.0 for good results.
Maybe you want to look at this thread:http://pixinsight.com/forum/index.php?topic=5583.0

For a quick "after" solution you can use the canon-banding-script. Because of the script can only reduce horizontal stripes, you have the rotate your images by 90 degree first. The result is far from perfect, but the picture is much better than before. Maybe it will work better with fits-file.

Greetings
Tobias

[cmassa]

I think I'm finding that my darks are at too low a temp compared to the lights. We are in the middle of a heat wave (>100F daytime) for the last 2 weeks. My sensor temps are pushing 40C and above. I think I was using darks at 32C. Maybe that was it.

I did try the canon banding remove script but it didn't work for some reason. It gave an error and shut down. I'm not really sure how to use it. Do you just have one file open in the window and hit OK?

My master bias is made from 200 frames at -7C and then made into a superbias. I was told on a forum that this was the better method for a master bias and it has worked well. I think the current issue may be the darks.

Chris

[TobiasLindemann]

-darks: Hm, a difference of 8 degree is not perfect, but I am not sure if this is the reason.

-banding-script: Hm, I only rotated the image with FastRotation by 90 degree clockwise and than hit the ok-button of the CanonBandingReduction. Normally I activate the preview of the script, but without it worked for me too. Sorry, I had never an error of this script.

-bias: 200+superbias should be enough, but I am not sure of the temperature. IMHO the biases should be of about the same temp. as the lights, but I am not sure. I would be very interested in other opinions.

Tobias
 

[lucchett]

Hi,
I don't know if it is helpful, but the same happened once to me on master flat integration.
The analysis showed that I did a mistake in tuning the rejection algorithm.
I do not remember exactly the mistake I did but the result was very similar (even if on mono CCD camera)

Andrea

[gvanhau]

To me, it seems like an pattern itroduced by electrical interference.

Time ago, I used a cheap AC adaptor instead of batteries in my Canon XSi. 
Some noise got into the frames trough the AC line and I got a  similar result as yours.


Geert

[cmassa]

Well, I am using a cheap AC adapter. I made a new set of darks and bias frames and it got better but not gone.

My problem with batteries - I don't stay up to change them. I use Sequence Generator to program the night's imaging and go to bed.

I may have to do a trial with batteries just to see what happens.

Chris