Ngc 4945

Paul Haese · #1 29-06-2009, 01:29 PM

Took this image last night in 1/4 moon light. 16 subs at 10 minutes. Not overly happy with the image overall. It has noise and some other artifacts.

The reflections problem has been sorted which I am really happy about.

Collimation needs some more attention too.

Click Here

Comments welcome.

bloodhound31 · #2 29-06-2009, 01:42 PM

Looks MUCH better without those reflections Paul. How did you solve them?

Baz.

Hagar (Doug) · #3 29-06-2009, 02:24 PM

Nice image Paul, but not up to your normal. The galaxy although a very dim one, seems very dark without resolution. At least you have had a night you can see the sky. Suffering withdrawal here.

jjjnettie (Jeanette) · #4 29-06-2009, 02:25 PM

Maybe it's just my inexperience, but I can't see too much wrong with this image.
The detail of the dust lanes is impressive.
What scope do you use Paul?

telecasterguru (Frank) · #5 29-06-2009, 02:29 PM

Paul,

Seems like a pretty good image to me. It looks pretty luminous and transparent. I like it a lot.

Frank

TrevorW · #6 29-06-2009, 02:29 PM

Paul can see what you mean by the star shapes probably a result of taking it apart, resolution not up to you usual standards but interesting target nevertheless.

RB (Andrew) · #7 29-06-2009, 02:41 PM

Paul on this image there's a slight magenta colour cast.
Try boosting the green channel using something like +12 (green) in the midtones under colour balance and see how it looks.
Once you get all three curves to line up you'll see an improvement in the colour balance.

Paul Haese · #8 29-06-2009, 02:53 PM

Baz, click on this link to see how I sorted the problem.

Doug, yeah not sure what happened here. 10 minute subs should have been enough, but I think a combination of slight miscollimation and maybe the need for much longer subs would have helped. The moonlight would also have had a negative effect too. Nearly 1/4 moon was pretty bright. Oh well next time.

Mind you have not seen the sky much this year too, so I understand where you are coming from.

Trevor, I think I need a tak collimation scope, that will sort the star shapes out. Mind you it could be the dew strap that is around the secondary causing the star flaring. Might have to take it off and see is that makes a difference.

Paul Haese · #9 29-06-2009, 03:10 PM

RB, sorry you must have posted just as I did. If you refresh the image now it should be as you suggested. Thanks for picking that up. Must be tired not seeing the magenta. Also boosted the levels too.

RB (Andrew) · #10 29-06-2009, 03:20 PM

Beauty Paul.

jase (Jason) · #11 29-06-2009, 06:08 PM

Good to see you've got rid of those reflections Paul. A very pleasing image indeed. Not too certain about the star sizes, suspect the seeing was rather woeful. Shows potential, looking forward to your progress now the main issues are out the way.

Paul Haese · #12 29-06-2009, 08:27 PM

Jase, thanks, but I reckon the star sizes are here to stay. I reckon it is partly to do with the pixels on the 40D and well it is an RC but not a CDK or RCOS. That last 10% is where the star sizes are smaller. Mostly I reckon the star sizes are from over sampling on the chip.

I do need to chase down a Tak collimating scope though.

strongmanmike (Michael) · #13 29-06-2009, 10:32 PM

Overall a pleasing image of a great galaxy Paul

Quite a natural look to your processing so well done.

Mike

Paul Haese · #14 29-06-2009, 10:59 PM

Thanks all, well I found out the reason for the noise. Only 4 images got stacked. Bizzare I could have sworn I placed more in the stack. So now I have 16 fully stacked and the noise is greatly reduced and there appears to be sharper detail. Maybe I have been looking at this screen too long.

Thoughts?

erick (Eric) · #15 29-06-2009, 11:38 PM

Well I don't know much, but looks lovely to me, certainly better than the version I saw earlier today. One of my favourite galaxies.

Tamtarn · #16 30-06-2009, 04:41 PM

It's not an easy one to process Paul. We found the galaxy was quite dim in our DSLR subs so you've done well to extract the detail considering 1/4 moonlight.

RB (Andrew) · #17 30-06-2009, 08:13 PM

Quote:

Originally Posted by Paul Haese

Thanks all, well I found out the reason for the noise. Only 4 images got stacked. Bizzare I could have sworn I placed more in the stack. So now I have 16 fully stacked and the noise is greatly reduced and there appears to be sharper detail. Maybe I have been looking at this screen too long.

Thoughts?

Paul, it's a big improvement over the original, the extra subs have reduced the noise levels significantly.

Hagar (Doug) · #18 30-06-2009, 08:32 PM

Big diference Paul. Much more like your usual.

Well done.

Alchemy (Clive) · #19 04-07-2009, 03:33 PM

the galaxy is pretty good, always difficult to process such an object in a busy starfield.

clive