Horizontal banding on Canon 550d

[Stub Mandrel]

5 hours ago, Gerry Casa Christiana said:

That's almost exactly the curve I did  I found it by trial and error. 

I stole it off Olly ?

[Adam J]

This sort of thing is why you should always perform a large ish scale dither on CMOS camera subs.

[emyliano2000]

1 hour ago, Adam J said:

This sort of thing is why you should always perform a large ish scale dither on CMOS camera subs.

I dither but only 5 px, APT won't let me do more when guiding with PHD2. Would increasing the dithering distance reduce the banding?

[michael8554]

21 hours ago, emyliano2000 said:

I dither but only 5 px

Is that how far the guidecam dithers?

That will usually translate to a much larger dither in pixels of the imaging camera.

Image scale of the guidecam compared to image scale of the imaging camera.

Michael

[Adam J]

On 24/05/2018 at 21:49, emyliano2000 said:

I dither but only 5 px, APT won't let me do more when guiding with PHD2. Would increasing the dithering distance reduce the banding?

You can change dither scale within PHD2, you should be dithering at the same scale as the banding

[emyliano2000]

14 hours ago, Adam J said:

You can change dither scale within PHD2, you should be dithering at the same scale as the banding

I'm fairly new to phd2, I need to fing where this setting is.

[david_taurus83]

22 hours ago, Adam J said:

You can change dither scale within PHD2, you should be dithering at the same scale as the banding

I too would like to know this. I believe the 1 to 5 value in APT is a rate, of what I don't know. I'm on 5 and it makes a noticeable movement in the subs bit I'm not sure by how many pixels.

[emyliano2000]

Well if my calculations are correct the 9x50 (180mm fical length) finder-guider with the qhy5 (5.2um pixel size) guidecam give me a resolution of 5.96 arcsec/pixel and for the ts65q (420mm focal lengh) with my canon 600d (4.3um pixel size) I have 2.11 arcsec/pixel so if the dithering is done by 5 pixels that means the telescope will be moved 29.8 arcseconds meaning that my ts65q with the canon 600d will be at a distance of 14.12 pixels from the previous position? Is it good or bad?

And to be honest I thought the imaging camera will be moved 5 pixels not the guidecam.

[Gerry Casa Christiana]

Ok last night I did my first night to see if the banding was any better. It was COMPLETELY GONE  right so what did it. Not absolutely sure but 2 things I did differently then before. I didn't run the laptop on just the power of the battery. I used it's mains plug. The other thing I did was remove the SD card from my camera. Absolutely zero banding and yes my camera was hot 28-29 degrees. I did 8 minute subs. 

Ill post results from the short session I did. 

Gerry

[Gerry Casa Christiana]

Almost I should have said. Just checked again. It's there but much much fainter.