M22 Globular Cluster - Unguided!

dylan_odonnell (Dylan) · #1 22-09-2014, 04:14 PM

After several hours fiddling in the dark and cursing while all the cool stuff slowly dipped out of my yard's viewing area and into the trees, I managed to image this globular cluster.

The only reason I wasn't guiding is because PHD kept seizing every time I used Backyard EOS. I'm guessing the USB2 ports can't handle the new SSAGpro mono guide cam and my DSLR (both USB3) at the same time. Hopefully a powered USB3 hub will fix that?

I also didn't know what I was imaging until later when I ran the result through http://astrometry.net/ (What an amazing website) and it told me, in great detail.

Features : M22 and HD171961
Taken Sep 17th from Byron Bay NSW
10 x 30s exposures / unguided (+ same # exposures + time for Dark frames)
Celestron c9.25” SCT and CG-5 Mount
+ Focal Reducer (F 6.3)
Canon 70D + Backyard EOS
Stacked using Nebulosity
Original File Resolution : 5546 x 3682

I'm a little bit shocked it turned out at all! It's a small success for me in the pursuit of deep space astrophotography.

d

raymo · #2 22-09-2014, 04:29 PM

That would have been really nice, but your focus seems to be a bit off.
Is your focus usually fine, and this is a one off, or do you not have a foolproof method of focusing?
raymo

Amaranthus (Barry) · #3 22-09-2014, 04:47 PM

Focus seems good to me - the stars really jump out. Just a small hint of star trails. Nice work.

dylan_odonnell (Dylan) · #4 22-09-2014, 04:59 PM

Quote:

Originally Posted by raymo

That would have been really nice, but your focus seems to be a bit off.
Is your focus usually fine, and this is a one off, or do you not have a foolproof method of focusing?
raymo

I'm not sure.. if I zoom in at 100% on the full res I see nice sharp little distant stars, but the ones in the cluster are bigger and blobbier. I didn't sharpen this small res one for the forum as a last step which may have helped.

To focus I used the FWHM feature in backyard EOS to get the number down as low as possible .. but maybe I should've spent longer on this!

SimmoW (SIMON) · #5 22-09-2014, 05:25 PM

Nice one Dylan, yes maybe a bee's willy off in the focus but barely noticeable I reckon, wouldn't have picked it normally.

PeterEde (Peter) · #6 22-09-2014, 06:35 PM

Looks nice
Lots of colour in there

cometcatcher (Kevin) · #7 22-09-2014, 06:51 PM

Nice photo. I like the framing with the star and the colours. Focus seems fine to me. I get atmospherics that make the focus look worse than that. Could do with some flat frames or software flat field for even field illumination. But other than that it's very good.

PeterEde (Peter) · #8 22-09-2014, 07:02 PM

Dylan. Do you use live view to focus.
If you don't here's how I do it for faint objects
Set ISO as high as possible and your exposure time to max and set liveview to expsim. You should hopefuly get a few stars to focus on.
Otherwise focus on a bright object then mark the focus draw tube with a pencil the then you can always get close.
But this shot looks pretty good so I'll stop telling you what to do

PS don't forget to set ISO back to where you want it. Can be annoying shooting minute at high ISO

pluto (Hugh) · #9 22-09-2014, 07:26 PM

Looking great!, and nice to see it in a higher res than IG

If you want to take the guess work out of focusing get a bahtinov mask.

dylan_odonnell (Dylan) · #10 22-09-2014, 08:46 PM

Thanks Hugh .. I'll have to investigate using a bahtinov mask as on option!

Pete, the FWHM trick in Backyard EOS is live, except I don't have to rely on my eyes to tell me what's in focus.. by selecting a star and watching the histogram / value it can go sharper than what my feeble human eyes can discern (or so the theory goes!).

Thanks Kev! I did indeed neglect the flats. Which isn't forgivable shooting 5 meters from a streetlight really.

Thanks SimmoW!

Better / higher quality version here : http://deography.com/wp-content/uploads/2014/09/M22.jpg

LightningNZ (Cam) · #11 23-09-2014, 01:07 AM

Nice work Dylan. Looks plenty sharp to me! Try to resist the temptation to make the background perfectly black though, you're losing a little from the picture. As others have mentioned, if you use flats you can pull more detail out without uneven illumination of the background.

dylan_odonnell (Dylan) · #12 23-09-2014, 09:30 AM

Quote:

Originally Posted by LightningNZ

Nice work Dylan. Looks plenty sharp to me! Try to resist the temptation to make the background perfectly black though, you're losing a little from the picture. As others have mentioned, if you use flats you can pull more detail out without uneven illumination of the background.

That's good advice.. thank you!