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M51 image tweaks?

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#1 Jeffmar

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Posted 26 January 2020 - 09:55 PM

I have taken just a few photos of M51. You would almost have to call them snapshots. What I noticed in my photos and other folks M51 photos is the blooming stars that are not part of the galaxy. The HST photos have no blooming stars for obvious reasons. I would really love to get my photos looking a little more Hubble like, and I was wondering if anyone does editing to remove the blobs, and still get a good image. My only other alternative is to keep taking M51 shots until I get a night with exceptional seeing. 


Edited by Jeffmar, 26 January 2020 - 09:56 PM.


#2 Gipht

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Posted 26 January 2020 - 11:08 PM

I do two methods of star reduction.  Star Tools has a shrink command which modestly reduces  the size and brightness of the stars.  The second method is to use Gimps filter->noise reduction which makes a lot of smaller stars disappear.

 

Some people develop the star fields and galaxy image separately and combine them to get a better star field.

 

Here are two pictures one using the asi183mm pro(2.4 um),  and the right one using the Canon t3i (4.3 um).  Both pictures are taken with a 10" f/4 reflector.  Both images taken with the same mount, and guiding equipment.   They have been scaled to approximately the same size.  The t3i picture has smaller stars.  Why is this the case?  Better seeing, or guiding, or a more appropriate exposure time might be an explanation, but I really do not know.  Do some cameras bloat stars more?  I would guess the answer is yes.

 

 

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#3 Jeffmar

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Posted 27 January 2020 - 02:54 AM

I would guess seeing was better that night when you used your Canon. I don’t know if the pixel size could make a difference. I would think longer exposures might make star bloating worse because you are recording more deviations over time. The only one I am fairly sure about is seeing. 




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