M15

[PhilB]

Woopee, clear sky last night 

Here's my attempt at M15. Taken over midnight BST this is 40 x 30s images, stacked in Dawn and final processed in CS2. The camera was an ATIK 320E with IR filter on a 120mm f9 Skywatcher Equinox 'scope

[Mac]

nice capture.

Mac.

[RobertM]

No bad at all Phil, I bet you're very pleased with how it's come out and with the nearly full moon it must have been quite a challenge.

Processing wise, I would say that you should probably lighten up the background to bring out some more stars (I'm sure there are lots lurking there somewhere) but It's a very good start.  Also the bright star bottom left has a halo around it which looks like a sharpening artifact (possibly)?  If it is then I'd suggest that you don't sharpen too much as it's very easy to over do.

If this is guided then perhaps you should try 180s subs or more next time (but make sure the core isn't burnt out!).  I always do a couple of test images to work out ADU values before firing off the sequence.

Looks like that should be a very nice combination of scope and camera.

I'm looking forward to your next image now you have the bit between your teeth  

Robert

[Ian]

Phil, I'd say looking at the sharpening artifacts on that star in the bottom left hand corner that your focussing was perhaps not as good as it could be, and you've attempted to compensate using sharpening in processing?

Did you use a mask to find focus?

Exposure looks good, although I agree with Robert, a little less dark in the background and more stars will appear (this would be helped by really good focussing too)

[PhilB]

Yup, i think the halo is due to over sharpening. The background probably was lighter given the amount of stray light due to the moon and other sources. Trouble is I've always felt that space should be black, hence the tendency to over darken. As for the focus, I set this from the moon as I don't have a mask or such like for this 'scope at present.

[Ian]

I'd at least try a hartmann mask with three holes. Bit of card and some sellotape will work. If you want, you can make the holes triangular so you get some diffraction spikes as reference

[MarkS]

Well done Phil - especially with the moonlight and not bad for such short exposures.
The satisfaction of catching something like this out of the night sky is a great feeling.

I agree with the others that it is a tad oversharpened but don't let that put you off.

By the way - what is this Dawn you used for processing?

Mark

[PhilB]

Thanks, Mark. I shall probably go back and reprocess this image in the light of what has been said.

Dawn is an image processing and camera control package currently under development by Atik. It can be downloaded from Ian King Imaging.

[Fay]

Hard to get with the Moon phil, but yes try longer exposures when Moon has gone! Did you use lp filter?

[Tony G]

Nice image Phil.

Tony G

[PhilB]

Did you use lp filter?

No, the only filter was for IR.

I'm currently playing with this image in the light of what's been said, but the bright foreground star to the lower left remains a problem. I'll have to make up a mask to get the focus right.

[The Thing]

Nice image Phil. I would be happy with that, but as the others have said, there's probably a lot more stars lurking in that darkness!