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M57 Imaging Strategies?

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#1 ESzczesniak

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Posted 26 May 2023 - 05:29 PM

I'm looking to try M57 for the first time.  My scope will be a EdgeHD 8, probably with the reducer since it's setup that way for the rest of galaxy season.  And my camera will be either a 2600MM or MC (both available).

 

First, this should really be a RGB target, correct?  The coloring makes me think Hubble palette, and I see a few images stated to be acquired this way.  However, as a planetary nebula, there not really strong SII, Ha, or OIII emission, correct?  I have seen some comments to augment with some H-alpha for the exterior gas clouds. 

 

Second, what about capture strategy?  I've seen a few images that look really good capture with "lucky imaging".  They were using roughly 5 second exposures and thousands of them.  They also were imaging at almost 3000 mm FL. 

 

Then traditional with similar broadband exposures (3ish minutes).  These seem to lack detail, which makes sense with such a small target and long exposures affected by seeing. 

 

While relatively "bright", it's still a magnitude 8.8ish.  So my gut reaction to lucky imaging is that it wouldn't work well.  But again, thee results did look good.

 

Any insight or advice for capturing M57? Thank you for any thoughts?



#2 revans

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Posted 26 May 2023 - 06:13 PM

I'm looking to try M57 for the first time.  My scope will be a EdgeHD 8, probably with the reducer since it's setup that way for the rest of galaxy season.  And my camera will be either a 2600MM or MC (both available).

 

First, this should really be a RGB target, correct?  The coloring makes me think Hubble palette, and I see a few images stated to be acquired this way.  However, as a planetary nebula, there not really strong SII, Ha, or OIII emission, correct?  I have seen some comments to augment with some H-alpha for the exterior gas clouds. 

 

Second, what about capture strategy?  I've seen a few images that look really good capture with "lucky imaging".  They were using roughly 5 second exposures and thousands of them.  They also were imaging at almost 3000 mm FL. 

 

Then traditional with similar broadband exposures (3ish minutes).  These seem to lack detail, which makes sense with such a small target and long exposures affected by seeing. 

 

While relatively "bright", it's still a magnitude 8.8ish.  So my gut reaction to lucky imaging is that it wouldn't work well.  But again, thee results did look good.

 

Any insight or advice for capturing M57? Thank you for any thoughts?

I've only imaged it with a OSC camera.  The main thing is focal length.  I got my best image of it using a 12 inch scope at a focal length of 2700mm.  Ultimately you want to capture stars in the center of the donut.... I thought I got several of them at 2700mm.  Precise focus is very important.  It gives off plenty of light.  I would use your scope with just a UV/IR cut filter unless your sensor already has a UV/IR block protective window.  I wouldn't use a focal reducer.  I think your Edge 8 would be a little over 2000mm which should be nice.  

 

Rick



#3 ESzczesniak

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Posted 26 May 2023 - 06:24 PM

I’m assuming it’d be crazy to use a Barlow to get more FL like planetary imaging? If it’s plenty bright, it seems appealing. But getting guiding through an OAG in a 1.25” eyepiece tube seems rough. 



#4 dswtan

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Posted 26 May 2023 - 06:52 PM

It's really small -- try one of the previewers to see how small (Telescopius, etc.).

 

The 0.7x Celestron HD reducer isn't great (chromatic aberration on mine), and it's not doing you any favors with an APS-C chip for small targets. M57 is a great excuse to wean yourself off f/7 and get back to f/10 like nature intended; M57 is relatively bright compared to galaxies (though there is a dim "halo" -- and yes, maybe worth trying some Ha there, I personally haven't). Many of the planetaries are small, so you can keep at f/10. 

 

Definitely a fun experiment to try lucky imaging on DSO on this one, but I personally haven't.


Edited by dswtan, 26 May 2023 - 06:59 PM.


#5 dswtan

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Posted 26 May 2023 - 06:57 PM

I’m assuming it’d be crazy to use a Barlow to get more FL like planetary imaging? If it’s plenty bright, it seems appealing. But getting guiding through an OAG in a 1.25” eyepiece tube seems rough. 

Yes, crazy. slaphappy.gif  

 

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#6 TXLS99

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Posted 26 May 2023 - 07:55 PM

 

Definitely a fun experiment to try lucky imaging on DSO on this one, but I personally haven't.

Another member has done that experiment for us lol.gif

 

500ms x 50,000

 

https://www.cloudyni...ging-technique/

 

 

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