Why horizontal lines in image?

[Seanelly]

1 hour ago, alan4908 said:

I've had to look at your image and in addition to the horizontal lines you have a collection of dust donuts.  To minimize these, I suggest take some flats, the most consistent and reliable method that I've found to do this is via an EL panel.  If you find flats/darks/bias a bit of mystery then I'd getting a copy of Steve Richards excellent book  "Making Every Photon Count"  - https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

You can also minimize both of these unwanted effects in PS.  The horizontal lines can be minimized by one of Noel Carboni tools called Horizontal Band noise reduction, the dust donuts via the context sensitive spot healing brush in PS. You can download Noel tools from https://www.prodigitalsoftware.com/Astronomy_Tools_For_Full_Version.html  and represent excellent value at $21.95.

Alan

Thank you for the response and suggestions. I didn't think that flat/dark/bias frames were much of a mystery until now, as from what I read here in the past they sounded simple enough, though flats seemed such an arbitrary thing from the various info I gathered, but then I figured it was an indication that flats' gathering had wide parameters. Another example of corner-cutting on my part to try and get images as quickly as possible.

[Seanelly]

1 hour ago, prusling said:

I suffer from two distinct dark horizontal bands on my Canon and get rid of them after stacking by using the excellent free app Fitswork4 - using the function Processing, Background Flatten, Lines to Equal Values with standard parameters.

Thanks for the lead on the free app Fitswork4. If I can correct my problem and minimize my costs with PS at the same time I'm all over the suggestion!

[Scott_R_K]

Hello all ,

Just found this Topic while searching for Bayer Matrix Issues with Canon T6i/750D Cameras .

I too have just started noticing horizontal banding on my FLAT images , before any Debayering in DSS .

Yes there are Dust Motes and I know , as FLATS , all of this will get removed from my Lights during Calibration . But , does this also look like an AF Pixel issue ?

Thanks in advance ,

Scott...............

[Scott_R_K]

Not much action on this Topic but I have an Update and further questions .

It seems that "if" any of the RGB channels are clipped , as seen in a Histogram , then the AF Pixel Rows are very obvious .

Has anyone seen this or able to confirm this ? I'm still doing some Testing .

Scott..............