Specific noise from DSLR

[bottletopburly]

14 minutes ago, UCzerw said:

Gude scope 60/240mm, guide cam 3,75 upix

Imaging scope 72/420 + 0,85 reducer;  camera 4,3 upix

Scale 1,3x probably 

Apt dither of 7  should give you a dither of approx 18pixels ,6 will give approx 15 pixel dither .

[UCzerw]

Do you mean dithering distance in APT? I didn't change much in apt. Only time, because sometimes the mount goes crazy

 

[alacant]

15 hours ago, UCzerw said:

"smudges" of noise.

Hi

Try a bigger dither with windsored sigma clip at e.g. 3 3. The debayer looks like it's left a grid too. Try RCD.

If you're not keen on spending time processing (I'm not!) I think you're gonna have to get an astro camera, use your Nikon or simply take more frames with the 600. Otherwise, it's easily corrected.

Cheers

[UCzerw]

59 minutes ago, alacant said:

Hi

Try a bigger dither with windsored sigma clip at e.g. 3 3. The debayer looks like it's left a grid too. Try RCD.

If you're not keen on spending time processing (I'm not!) I think you're gonna have to get an astro camera, use your Nikon or simply take more frames with the 600. Otherwise, it's easily corrected.

Cheers

 

Thanks. I used the latest version of Siril. A few days ago it was published and I can see that the RCD is set by default.
Damn white nights. Terribly short, but now the moon is coming, it will be a bit of a rest.
I'm seriously starting to think about a cooled camera, I have to look for information that is worth choosing at the beginning.

I just wonder if this noise on the red channel is normal? Single light frame, auto stretch.

[alacant]

2 hours ago, UCzerw said:

noise on the red channel

Hi

Can't tell. Please post -links to- 

• a single light frame
• a single bias frame
• master bias
• final stack

We use mainly a -same sensor i think- 700d, but don't see the noise you illustrate. 

Cheers

Edited June 12, 2021 by alacant

[UCzerw]

• a single light frame
• a single bias frame
• master bias
• final stack

Hope everything works.

[alacant]

1 hour ago, UCzerw said:

Hope everything works

Yes. OK. It seems the red overpowers the other two channels. 

JTOL, it's like both the hot mirror and the moire ir filter have been removed. Is that the case?

Anyway, it'd doable, but makes processing more difficult than need be.

There is not nearly enough dither. To lose the walk with a 600d, you're gonna need at least 10px and between every frame. See @bottletopburly's calculation, here. 

With a refractor, an ir cut filter can often help with stuff like this, especially for full spectrum modifications.

That should make it a lot cleaner.

Just our €0.02 hands on. Maybe the theorists could throw some light on the matter too, but hey, for a camera which has 10 year old technology, it's very good. There's loadsa faint stuff showing

HTH

 

 

Edited June 12, 2021 by alacant

[UCzerw]

I think only one filter has been removed. It is not a full spectrum mod. I received one filter as a souvenir, and the person who made the modifications thinks that there is no need to remove two filters.

But soon the Moon comes into play, and so far I'm not using filters. Besides, I might have a problem with that. SkyWatcher is smart . Their reducer does not support filters 😅

I'll try to increase the dithering. I just don't understand these calculations. If I have a 1.3x scale difference (image / guide scale). In phd2 I have dither scale set to 10. In APT I have set to 1. So that's 13 pixels. If I change dither distance to 2 in APT, I will get an offset of 26 pixels. Setting APT dither to 7 will give me over 70 pixels.
Am I counting something wrong? There is any "sweet point" how many pixels should I set for dithering?

 

[alacant]

7 minutes ago, UCzerw said:

the Moon comes into play

You have a week at least before that becomes an issue:)

8 minutes ago, UCzerw said:

don't understand these calculations.

https://aptforum.com/phpbb/viewtopic.php?t=3154

 

[bottletopburly]

17 hours ago, UCzerw said:

Do you mean dithering distance in APT? I didn't change much in apt. Only time, because sometimes the mount goes crazy

 

Yes change dither distance to 6 for a maximum dither of 16 see how that goes 

[UCzerw]

1 minute ago, bottletopburly said:

Yes change dither distance to 6 for a maximum dither of 16 see how that goes 

And leave dither scale 10 in phd2?

[bottletopburly]

Just now, UCzerw said:

And leave dither scale 10 in phd2?

No change to default think it’s 1 

[bottletopburly]

My original calculation sheet https://aptforum.com/phpbb/download/file.php?id=2672

download and open in a spreadsheet  and rename file you should be able input values that’s what I did for yours 

Edited June 12, 2021 by bottletopburly

[UCzerw]

I'll try next clear night.

Thank you gentlemens.

[bottletopburly]

Nice article here I just got my lad to do a spreadsheet based on a formula posted on Apt forum  

https://www.myastroscience.com/calculatedithering

Edited June 12, 2021 by bottletopburly

[UCzerw]

11 minutes ago, bottletopburly said:

Nice article here I just got my lad to do a spreadsheet based on a formula posted on Apt forum  

https://www.myastroscience.com/calculatedithering

I found it. But I have considerable gaps in knowledge. After graduation, I have to work hard on the theoretical foundations of astrophotography.
Excel show to set APT to 2