Skywatcher Coma Corrector and 150PDS

[adyj1]

I have recently added a sw cc to my setup, and have noticed an anomaly when photographing bright stars during my alignemnt (see pic below - the coloured blur to the right of Capella). I *think* I read something saying this can happen when I was researching coma corrector, but can't find it now.

Thinking about it now, I attached the coma corrector to the camera (Canon 200d) using the tube it came attached to when I bought it second-hand - rather than trying the others that also came with the package - and it seemed to work ok. Should I be doing something scientific to check I have the correct spacing?  

So, my questions are; a) is this to be expected? b) should I do something to check the spacing?  

Many thanks

Ady

[alacant]

Hi. Yeah, the sw cc suffers from reflections, so just avoid targets with bright stars nearby. That's not such a disadvantage as it sounds as very few targets you'd want to shoot with a 150mm reflector have bright stars in the field of view.

Spacing: a 10mm canon to m48 adaptor gives you the correct distance so that's not really something to check but your shot looks good as far as correction is concerned. Can you send a photo of what you have?

HTH

[adyj1]

Thanks, I'll sort it out tonight. From what you've said, I think I've got the right spacing. 

I'll have to bear that in mind for the horsehead and flame Nebula in Orion, which I'm hoping to do with guiding this year. The 150 frames them well, with Alnitak nestling brightly between them ? 

Ady

[RolandKol]

I never had such a problem with my 130PDS and SW CC,

just out of curiosity, -

Scope flocking? Would it sort out or maybe reduce such a stray light issue?

[Adam J]

44 minutes ago, adyj1 said:

Thanks, I'll sort it out tonight. From what you've said, I think I've got the right spacing. 

I'll have to bear that in mind for the horsehead and flame Nebula in Orion, which I'm hoping to do with guiding this year. The 150 frames them well, with Alnitak nestling brightly between them ? 

Ady

Alnitak is always a problem for everyone irrespective of setup. 

[alacant]

Hi again. I think screwing a filter or a filter -e.g. an ir cut or lp- on a short extension on the m48 at the front of the cc moves the reflection out of frame or minimises it. Experiment by using different extensions...

HTH

[adyj1]

55 minutes ago, alacant said:

Hi again. I think screwing a filter or a filter -e.g. an ir cut or lp- on a short extension on the m48 at the front of the cc moves the reflection out of frame or minimises it. Experiment by using different extensions...

HTH

I'll give it a go. I only have a UHC filter currently, so I'll try that. Assuming clear skies soon!

Thanks

Ady

[Stub Mandrel]

6 hours ago, adyj1 said:

I have recently added a sw cc to my setup, and have noticed an anomaly when photographing bright stars during my alignemnt (see pic below - the coloured blur to the right of Capella). I *think* I read something saying this can happen when I was researching coma corrector, but can't find it now.

Thinking about it now, I attached the coma corrector to the camera (Canon 200d) using the tube it came attached to when I bought it second-hand - rather than trying the others that also came with the package - and it seemed to work ok. Should I be doing something scientific to check I have the correct spacing?  

So, my questions are; a) is this to be expected? b) should I do something to check the spacing?  

Many thanks

Ady

There are few targets bright enough to cause an issue. Alnitak is one, but a few dabs with a clone tool solve the problem.