After Dave and Barb's great shot of this area I thought I would have a try at an RGB with a GRAS ASA 16 to see how I could process R G and B subs. One of the areas I am having difficulty with is developing each of the stacked R G & B subs up to a level where they can be combined. If I use DD in Nebulousity or stretching in MAxim DL, the standard settings give quite different variations and I end up doing a lot of fiddling. I'm sure there's an easy method and a book to show me the way.
So comments welcome. Craig
R 3X5 min subs
G 3X5 min subs
B 3X5 min subs
Scope ASA 16, FLI PL11002M
Stacked and processed in Nebulousity. Finished in PS CS3
Graig I'm not up with this RGB imaging you speak of, but I find your image very interesting, with substantial detail and spot on focusing, well done indeed.
Thanks Leon. Trying to decide whether to get a mono CCD but takes a lot more work (and money) to get the colour. Processing each of the three stacks, and then the combined RGB shot. Lot to be said for the OSC.
Wow an ASA 16 and a FLI Proline 11002. That will have Mike chewing on a piece of wood. Did you have any problems with it and is the focuser working fine?
Your image indicates its all good.
I can only comment on my workflow which is:
1. I take twilight flats with a white T-shirt over the end of the scope and build up a dark library when its cloudy. Try to get 16 darks and standardise your temp and exposure lengths so you don't end up with 30 different darks. -35C is what Mike uses with his FLI PL11002 as you can achieve that temp all year. 10 minutes is probably a good time although 5 will mean less tracking/flexure issues.
2. I'd go for a minimum of 2.5 hours and usually 6 but then your scope is 16 inches and F3.6 or so so you will be able to get away with shorter total exposures.
3. I use Baader filters and also Astronomiks. Some filters are harder to work with than others. I used to use Astrodons and liked them although they may have reflection issues with your Keller corrector.
4. I use CCDsoft for acquisition so can't comment on Maxim which many use and is an excellent pgm.
5. I use CCDstack to do the base processing then Photoshop CS2.
Subtract darks, flats. Remove hot/cold pixels, register with higgh precision plugin for CCDstack (its worth using CCDstack for that plugin alone), then combine usually using median. Save as masters.
I usually run deconvolution 40 iterations (times through) all masters
and I click around on various stars until I find one with a low FWHM (a measure of the tightness of the star) and use it as the reference star.
6. I use CCDstack to combine the LRGB. I usually normalise the RGB before I combine (not always but usually have to with the above filters, with the Astrodons I did not have to). Once I get a an acceptable colour combine I save it.
7. Open in Photoshop and do colour processing/Ha combine. Don't overdo colour processing - the light and subtle touch will be the one that makes the image others like not the heavy handed over saturated over sharpened one. Ideal processing looks natural like you did nothing.
Your image is too heavy in red and not enough blue. So I would open it PS and click on the histogram and for all colour channels so you can see all the colour histograms. You'll now notice green and blue histograms are way different to red. So adjust them so the histogram starts in the same spot on the graph.
There should be more blue in those reflection nebula areas around the brighter stars. Look at Rob Gendler's images of the object you are processing as a guide to how you are going.
Hey, thanks for all the points Greg and your comment Peter. Didn't mean to give the impression it was my scope - a GRAS - as I have mentioned before trying the Lightbuckets as well. It's a good way to test some equipment and try out the processes before embarking on new expenditure and retiring my Tak Sky 90.
Will have a look at Rob Gendler's image - I must do more of this before I post so I have a reference. Thought it was lacking some blue.
Will also try looking at CCD stack and normalising the images before combine. Thanks again Greg for all the good tips.
Amazing image Craig - very impressed with this one.
The Detail and sharpness is bang on.
And RGB only! No mucking around with Ha on this one??
Lovely image
Doug
Hey thanks Doug for the comments but will have another go at processing. Greg has some good pointers. If I get a better balance I might try some Luminousity as well, or Ha.
