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Advice needed on image

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#1 John_77

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Posted 19 October 2020 - 04:22 PM

Hello everyone! I have just recently been getting back out and trying to get better at imaging DSOs. I redid a photo I had taken a couple of months ago of the Horse Head nebula but this time improving on almost everything I had done previously.

 

I am using a CPC800 and Hyperstar setup with a Starlight Xpress SXVR-H9C and Baader UHC-S filter. Last time my collimation and focus were off as well as being used in an Alt-Az configuration. This time around I made sure to take my time to collimate and focus the system, set up the CPC 800 on a wedge, do a proper polar alignment, and start guiding with PHD2. I checked FWHM in MaximDL to get focus set. This was all in hopes to get crisper, more detailed images.

 

Unfortunately, the images didn't turn out much more detailed or crisper than the old image. I am wondering if anyone could let me know what is causing this and if it is a limitation of the camera, my ability, seeing, lack of subs, etc. I should mention before going any further that the resulting image only consists of 30 sixty second subs stacked and calibrated with darks, flats, and bias frames. The images were taken with the chip cooled to -10C. I was hoping to see the image sharper but it still came out looking quite fuzzy.

 

My post-processing skills still haven't gotten any better and to be honest, I am interested to see what someone with more experience could do with the images.

 

I made a previous post asking for help that includes the first image I took, but I will paste a link to it and the new image below.

Any and all advice will be greatly appreciated!

 

P.S. I noticed many more red, green, and blue "hot" pixels in my latest image despite using dark frames. I can actually notice these spots light up in some of the frames, just for them to disappear in the next and pop up again later. Any insight into this matter as well would be greatly appreciated.

 

 

Old Photo: Here

 

New Photo: Here


Edited by John_77, 19 October 2020 - 04:24 PM.


#2 John_77

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Posted 19 October 2020 - 04:26 PM

With all of that said, there most certainly is a slight improvement, but not quite what I had been hoping for given everything I had improved on.



#3 rgsalinger

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Posted 19 October 2020 - 05:27 PM

I think that you will find that the subs are too short and that there are not enough of them. They are not getting far enough above the read noise in 30 seconds so that they are noisy. With only 30 minutes of integration time, you really don't have enough SNR for a good shot. If you're setup can tolerate it, take more longer exposures for better results. Posting some in a drop box might show that I'm right/wrong, this is just an (hopefully educated) guess.

Rgrds-Ross




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