Initial try at M51

[lalou]

Hi All. Need your help on my first try at M51. After stacking around 1 hour+ of 2 mins exposures this is what I got. I wasn't able to use darks and flats because I had a problem with the darks that I took during that night. I'm getting a slight red tone on the background when I enhance with levels and curves in Photoshop. I took the image in a fairly dark site but I used a UHC filter to see if it has any help on the image. My equipment is a Celestron C6N reflector, Nikon D90, and a Baader UHC filter.

 

Thanks!

[Stub Mandrel]

Give the trial version of gradient exterminator ago. Just create a mask with a hole for the galaxy and set it for 'balance background', 'coarse' and 'aggressive'.

It will give you a very well balanced background.

Best done after your initial stretch, in my experience.

[gorann]

Yes, fixing the background with Gradient Exterminator is a good start. Then you can make your stars round using this technique (see the post by Olly Penrice):

https://stargazerslounge.com/topic/299515-m33/?tab=comments#comment-3277659

Darken the background using curves

Finally, Use some noise reduction on the background and the Lab Color technique to bring out more colour in the galaxy, see:

http://www.dl-digital.com/astrophoto/p2-astro/Astro-Workflow.htm

Then it can look like this:

A few other points: When you use curves in PS you can use them separately for each color (good to fix anything from an odd background colour, to star colours). Darks is probably of no use since you have a DSLR where the temperature will vary on the chip (darks need to be taken exactly at the same temperature as the images.