47 Tuc (need processing tips)

traveller (Bo) · #1 02-09-2014, 10:30 PM

47 Tuc from last Sat in light polluted Melbourne. Taken with full spectrum modded 1100D with EOS UV/IR clip in filter.
I tried to stack 10x30 sec subs plus 10x45 sec subs both at 3200 but the core was really blown out.
So I just processed 10x30 sec subs with equal darks, slightly off focus but it has too much red. I am still learning to process, so tips welcome.
PS: will try again with a broadband light pollution filter next to see if it makes any difference.
Thanks
Bo

Tony_ (Tony) · #2 02-09-2014, 11:38 PM

G'day Bo,

Your image is quite good - just needs some more processing.
In my quick example I have reduced the red, increased the saturation and sharpened it a little. Could still be better - I'm not that great at processing myself. It still needs a bit more color balance. I also have a tendency to over process.
I did this in photoshop - if you don't have photoshop you can download a free software called GIMP.
If you are interested I can give you more details of how to do this.

Regards,
Tony.

Rex · #3 03-09-2014, 07:25 AM

G'day Bo, your image is really quite good, nice detail and the star colours are there. The LP is obviously a problem in your area as you said. There is a tutorial for photoshop that shows you how to remove the gradient. It doesn't do a perfect job but it will help a lot. I will find it and post a link tonight. A LP filter will help immensely, so I think your next try will have a much easier gradient to remove. Also try using a lower ISO if you can, it just makes it so much easier to process. I use eaither ISO 1600, or if I can I use ISO 800. Hope that helps.

traveller (Bo) · #4 03-09-2014, 09:48 AM

Tony: thanks for the tips, I will have another go at balancing the colours out a bit more. I have photoshop but still learning the processing side of things as you can clearly see.
Rex: Thank for the suggestion re lower ISO. I will definitely try that next time. I am surprised how much can be captured in such a short time. I will also slap on a broadband filter over the nosepiece next time (which I am sure will help to improve contrast and decrease the LP).
Will keep trying.
Cheers
Bo

Rex · #5 03-09-2014, 06:48 PM

Hey Bo, here is that link if you are interested mate. Its pretty easy to do and does help somewhat from my experience.

http://www.youtube.com/watch?v=yTEVMH_WE80

LightningNZ (Cam) · #6 03-09-2014, 09:53 PM

Nice pic of a great glob Bo. Nice round stars.

Don't worry too much about the core being blown out - 47 is so dense that the core is pretty much always blown out.

Thanks for the link Rex - that's a handy tutorial.

traveller (Bo) · #7 03-09-2014, 11:06 PM

Thanks Cam.
Rex, I tried removing the gradient, some success.
See this image.
Bo

raymo · #8 04-09-2014, 01:04 AM

47 Tuc needs several very short subs [5-8 secs] @800 ISO to limit the blowing out of the core.
raymo

cometcatcher (Kevin) · #9 04-09-2014, 01:24 AM

There's a few ways of adjusting the colour in Photoshop. Perhaps the easiest way is menu --> image / adjustments / colour balance and play with the sliders. Or image / adjustments / levels, choose a colour channel and play with the sliders again. It also helps to have the histogram open. Go to window / tick histogram. In histogram / channel choose colours. If you even these up with the other sliders the colour becomes more neutral.

Tony_ (Tony) · #10 04-09-2014, 10:02 PM

G'day Bo,

Don't worry about the gradient so much at first. Use levels (mostly) and curves to adjust brightness etc. and color balance.
Use saturation to increase the color - you can use color select or other method to select stars only (to avoid increasing background color). There are tutorials on youtube. Don't increase the saturation too much in one go - do it in stages or you can over-saturate the color on some stars.
Once you are happy with the balance and color then you can work on the gradient (which isn't too bad).
Download a free software called Hasta La Vista Green - it is an add on for photoshop that helps get rid of unwanted green. In general there aren't many green hues in objects, except some planetary nebulae and comets and alternate color palettes.
If you spend a bit of time on this image you will find that it is really quite good - and you will learn a lot too.

These youtube videos are good:
http://www.youtube.com/channel/UCJ5b6pFHBGe66vsuSaXb-0A

Regards,
Tony.

Rex · #11 06-09-2014, 08:59 AM

Hi Bo, nice going removing the gradient mate. Correct me if I am wrong but did you use that technique in the tutorial on the image you posted earlier? I should have mentioned that gradient removal should be the very first step after stacking before doing anything else to your image. When you stretch an image with a gradient you basically are stretching the gradient out with the image data, which makes it harder to remove without damaging the data that you want to keep. So if I am correct in my assumption above, you may want to try it on the stacked image and then do your normal processing and see how that goes. Processing is a never ending learning curve, that at times is very slippery. Every now and then we have a breakthrough and our images take a leap forward in what we can produce, only to find that then there is some other artifact or issue that we need to try to fix. The only thing that helps is practice and that means many hours of frustration in the short term, but long term it all becomes worth it.