Astap and Canon 600D issues

[Endolf]

Hi

I've just started in this hobby, I've managed to get a couple of nights using my partners Canon 1000D and all was well (for a noob), I managed to get light and dark frames and stack them.

Yesterday a second hand 600D arrived and so did some clear skies. I went out and got 20 minutes on the Orion nebula.

I've been unable to get astap to stack them. It fails to solve any of the images (Stellarmate had done plate solving already to align everything) and if I try to view the images in astap I can't get the colours right. The fits header does have the Bayer pattern as gbrg which I believe is correct for this camera, the 1000D was rggb. 

The images open fine in kstars.

I'm Linux based so any suggestions for alternative stacking software would need to work there.

Thanks

[TerryMcK]

The 600D is also RGGB. You could try AstroPixelProcessor which is ported to Linux Debian and RPM as well as Winders and Mac OS

Edited March 3, 2020 by TerryMcK

[Endolf]

Thanks, I'll take a look at APP, ekos always says the Bayer pattern is gbrg, which is worrying if it's not. I tried forcing astap to debater using all of the options and still ended up with odd colours. I did manage to get it to stack though, for some reason the "debayer osc images" was unticked, so it was trying to solve stack images without debayering them. That's one issue solved anyway...

Thanks.

[Endolf]

I've managed to get ASTAP stacking and producing an image tonight. I had to force it to use GBRG debayer pattern, but when I do, I get an image that looks ok in Kstars. If I load it in GIMP and auto white balance on it, other than being blown out, the colours look right. I just need to figure out how to adjust that manually now so I can prevent clipping of the data.

[david_taurus83]

Canon 600D is 100% RGGB Bayer pattern.

[Endolf]

I'll confess then, I'm really confused. If I force ASTAP to debayer using GBRG and set the range to 16k then I get an image that looks about right (for something that was done without cool down time and is only 8 minute of exposure, no flats etc)

[michael8554]

All Canon DSLRs are RGGB. 

But some software is set up to read the Bayer pattern differently. 

The Bayer pattern repeats RGGBRGGB etc. 

If the pattern is read three pixels to the right you get GBRG, which is apparently how your software is reading the pattern. 

Why they have chosen to do that beats me. 

Take some daytime landscapes and experiment till you get realistic colours. 

Michael 

[han59]

This difference can be explained If the image is vertical flipped somewhere in the process. There are only four Bayer patterns possible so it doesn't matter so much:

Normally RGGB:

R G

G B

 

Vertical flipped GBRG:

G B

R G

 

For correct colours, use ASTAP auto colour correction. See tab Stack method "Auto Level and colour smooth" or after stacking go to  tab pixel math 1 "Colour correction". It will adjust R, G, B such that background is gray and average star colour is white. But it looks like you already have a nice image.

Han

p.s. why is this UK site suggesting to change colour to the American color?

 

 

 

[Endolf]

Great, thank you for the explanation, I was getting quite confused.

I've now just got to solve the fact that the focuser is so far that it sticks out in the tube, and the fact that it's only a 1.25" focuser, and I have only Bortle 6 skies so I could do with some light pollution filters, and I could do with a guid scope and camera for longer exposures, and on and on 😆

Thanks again.

[michael8554]

Also reading two rows unflipped:

R G   G B    R G G B.       Row 1

G B    R G   G B R G.       Row 2

Read 3 pixels to the right gives same result 

I don't get a spelling suggestion from SGL  to enter color, but my tablet keyboard does. 

Michael 

Edited March 4, 2020 by michael8554

[bottletopburly]

1 hour ago, michael8554 said:

I don't get a spelling suggestion from SGL  to enter color, but my tablet keyboard does. 

Michael 

Probably down to settings -USA keyboard same with windows change to uk keyboard 

Edited March 4, 2020 by bottletopburly