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Planetary imaging with 2x Barlow

planet astrophotography equipment
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#1 mhorbacz

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Posted 09 July 2020 - 06:07 PM

I am having some issues using my 2x Barlow in my planetary imaging setup. I have an 8" F6.3 SCT, in which i use an ASI120 MM to image planets. If i do it natively (no barlow) then i can get great pictures that react nicely when i sharpen them in Rexistax. But when i introduce my 2X barlow into the setup, i am unable to sharpen the final image to pull out additional detail. Instead, it just gets more and more grainy. This IS a lower end barlow (Orion shorty) so that is one thing i am suspecting might be the problem.  F/13 isnt THAT much magnification, so I doubt that the culprit is just bad seeing. Do you guys think its just that my barlow is too low of a quality and is degrading my final image this much?

Thanks for taking the time to help me out!

 

- The Potato In the Sky

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#2 descott12

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Posted 09 July 2020 - 06:12 PM

SCTs are typically f10 natively. Are you actually using the barlow with a reducer at the same time?



#3 mmarapa62

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Posted 09 July 2020 - 06:49 PM

I also frequently use an F6.3 Reducer with my C8 for DSO visual and imaging. However, I remove the reducer and go to F10 when I do planetary work. Get pretty good results with my ZWO ASI 224. I have tried to use a 2x (cheap) barlow at F20 but get crappy results. 

 

Good Luck!

 

  



#4 james7ca

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Posted 09 July 2020 - 07:12 PM

SCTs are typically f10 natively. Are you actually using the barlow with a reducer at the same time?

waytogo.gif

 

Dave is right, don't try to use a reducer with the barlow. That said, unless there is something wrong with the copy of the barlow you got then you should be able to use just about any barlow to get better results. But, the seeing, focus, and collimation will all become more critical.


Edited by james7ca, 09 July 2020 - 08:30 PM.


#5 RedLionNJ

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Posted 09 July 2020 - 08:07 PM

SCT's are (or used to be) available in both f/6.3 and f/10.  This is probably (as the OP posits) a native f/6.3 instrument. Not terribly difficult to believe - why is everybody questioning it?

 

Mr Potato - the only reason you might be getting "great pictures" at f/6.3 is because you're massively over-sampling. But by doing this, you're missing out on a ton of potential detail (when the seeing permits).

 

You should be aiming for somewhere nearer f/18 or so with the ASI120,  Do you know what f-ratio you ARE achieving with your Barlow? Just because is might say "2x" on it does not mean it is doubling your f/6.3 to f/12.6.  What does Firecapture or Winjupos say about it?

 

You'll only be using a tiny area in the middle of the barlow, so it's unlikely the quality is SO terrible as to cause the symptoms you're describing.   More likely, it's just poor seeing which is far less visible at f/6.3. Or you've had an unlucky series of circumstances where it's been particularly bad on nights with the higher f-ratios.

 

Posting some examples of the stacks (unsharpened) would be helpful here.



#6 mhorbacz

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Posted 09 July 2020 - 09:09 PM

SCTs are typically f10 natively. Are you actually using the barlow with a reducer at the same time?

Mine is a native F6.3


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#7 mhorbacz

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Posted 09 July 2020 - 09:11 PM

SCT's are (or used to be) available in both f/6.3 and f/10.  This is probably (as the OP posits) a native f/6.3 instrument. Not terribly difficult to believe - why is everybody questioning it?

 

Mr Potato - the only reason you might be getting "great pictures" at f/6.3 is because you're massively over-sampling. But by doing this, you're missing out on a ton of potential detail (when the seeing permits).

 

You should be aiming for somewhere nearer f/18 or so with the ASI120,  Do you know what f-ratio you ARE achieving with your Barlow? Just because is might say "2x" on it does not mean it is doubling your f/6.3 to f/12.6.  What does Firecapture or Winjupos say about it?

 

You'll only be using a tiny area in the middle of the barlow, so it's unlikely the quality is SO terrible as to cause the symptoms you're describing.   More likely, it's just poor seeing which is far less visible at f/6.3. Or you've had an unlucky series of circumstances where it's been particularly bad on nights with the higher f-ratios.

 

Posting some examples of the stacks (unsharpened) would be helpful here.

The next time I have the opportunity to get my scope out, ill grab images of planets using my 2x barlow and post them on here. I am unsure what my actual F ratio is. I use sharpcap and autostakkart 



#8 mhorbacz

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Posted 09 July 2020 - 09:46 PM

The next time I have the opportunity to get my scope out, ill grab images of planets using my 2x barlow and post them on here. I am unsure what my actual F ratio is. I use sharpcap and autostakkart 

 

SCT's are (or used to be) available in both f/6.3 and f/10.  This is probably (as the OP posits) a native f/6.3 instrument. Not terribly difficult to believe - why is everybody questioning it?

 

Mr Potato - the only reason you might be getting "great pictures" at f/6.3 is because you're massively over-sampling. But by doing this, you're missing out on a ton of potential detail (when the seeing permits).

 

You should be aiming for somewhere nearer f/18 or so with the ASI120,  Do you know what f-ratio you ARE achieving with your Barlow? Just because is might say "2x" on it does not mean it is doubling your f/6.3 to f/12.6.  What does Firecapture or Winjupos say about it?

 

You'll only be using a tiny area in the middle of the barlow, so it's unlikely the quality is SO terrible as to cause the symptoms you're describing.   More likely, it's just poor seeing which is far less visible at f/6.3. Or you've had an unlucky series of circumstances where it's been particularly bad on nights with the higher f-ratios.

 

Posting some examples of the stacks (unsharpened) would be helpful here.

So i just realized it was clear outside, so i brought out my telescope and got some video of jupiter...whats the best way to post the unsharpened imaged?



#9 RedLionNJ

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Posted 10 July 2020 - 08:49 PM

So i just realized it was clear outside, so i brought out my telescope and got some video of jupiter...whats the best way to post the unsharpened imaged?

Create a stack as you usually would, then turn the resulting image file into a JPG.



#10 mhorbacz

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Posted 11 July 2020 - 12:08 PM

The next time I have the opportunity to get my scope out, ill grab images of planets using my 2x barlow and post them on here. I am unsure what my actual F ratio is. I use sharpcap and autost

Create a stack as you usually would, then turn the resulting image file into a JPG.

This is using the 2X barlow. This does look better than previous attempts, so im thinking im just not hitting the focus right. I ordered a bahtinov already (figure I can use that even if focus is not the issue here)



#11 mhorbacz

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Posted 12 July 2020 - 05:15 PM

This is using the 2X barlow. This does look better than previous attempts, so im thinking im just not hitting the focus right. I ordered a bahtinov already (figure I can use that even if focus is not the issue here)

Sorry, forgot to hit "attach this file" on my last post :p

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  • Jupiter 7_9_20.jpg



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