M27 and M57 nebula's

doppler (Rick) · #1 21-07-2017, 11:49 AM

Finally a clear, cold night with very little dew to worry about. And as a bonus the GOTO was working nicely and guiding running smooth. Spent the evening snapping the brighter objects along the length of the MilkyWay. Here's one of M27 the Dumbbell nebula and M57 the Ring nebula in Lyra.

10" f4.8 Skywatcher newt, HEQ5 pro mount and 50mm finder guider, unmodded 1100D canon with baader MPCC Mark 3 coma corrector.

M27 8 X 2min subs at iso 800.
M57 6 X 30sec subs at iso 1600

cometcatcher (Kevin) · #2 21-07-2017, 01:02 PM

Nice ones Rick! Yeah the nights have been great. Not sure how many more we will get but trying to make the most of it.

doppler (Rick) · #3 22-07-2017, 08:18 AM

Thanks Kevin, a couple of more nice nights yet it seems and new moon as well. The 10" certainly makes the quick captures easy. I still haven't worked out the hoo ha about weight load issues when imaging, I am running at max "visual" payload without issue. Tube size makes balance a bit harder but weight doesn't seem to be a problem.

Anth10 (Anthony M) · #4 22-07-2017, 11:08 AM

Good stuff Rick! The 10s produce reasonable enough results for minimal exposure time for sure. Just stack more subs as Kev has proven and equally your shots are comparable no doubt using similar method.

I too stretch the limit with weight capacity with mine at 17.5kg fully loaded on the Neq6. Just got to place a bit of extra attention as you say with the balance and pick calm nights(if you have that luxury).
By the way how do you rate the baader coma corrector? Do you find it makes a noticeable difference with star rounding about the extremes of the image? Also do you use filters when using the corrector? I'm still looking at getting one to sharpen up my shots. Kevin reported positive results for his setup when I quizzed him, but your scope specs match mine at just under f5 so I'd be interested in your thoughts.
Thanks and well done again

Anth

doppler (Rick) · #5 22-07-2017, 05:54 PM

Hi Anth, the Baader corrector does clean up the corner stars quite well, the coma at f4.8 is not bad but noticeable. I've found some before and after pics for comparison. The before pics were done last year with no guiding, just tracking but the same ota.

The corrector is very fussy with focus and collimation, but at least the f4.8 is not as hard as the f4's to collimate. I did toss up whether to get the Skywatcher corrector as the f5 version had good revues. There did seem to be some colour aberrations on the corner stars, but these have got less visible with fine tuning the collimation and corrector spacing. The corrector is set up for Dslr use as is but I noticed tighter stars with the supplied thin spacer ring removed. The coma corrector is only a recent acquisition so I am still fine tuning it. I haven't used any filters yet but I am contemplating astro modding my spare 1100d after seeing Kevins shots with his modded DSLR.

Anth10 (Anthony M) · #6 22-07-2017, 08:02 PM

Good comparison, thanks. I understand no two setups are the same so accessories behave differently naturally, I do see that in your comparisons that there is a definate improvement but I notice that the top right in both images haven't corrected so well. I have this anomaly in all of my images. One corner is worst than the others. I'm glad however that your choice of corrector has been successful. I guess it's one of those things whereby you just have to try and see. I don't use guiding so I guess this would help too.
As for Astro modding your DSLR I say go for it, the results will be well and truly worth it!

doppler (Rick) · #7 22-07-2017, 08:30 PM

The top right was a lot worse before I recollimated the scope so I am hoping that with a bit more tweaking it might improve, it could also be the camera sensor not being square to the optics.

cometcatcher (Kevin) · #8 22-07-2017, 08:51 PM

F5 scopes definitely need correcting for coma. At F4 I still have some elongation at the edges even with the CC but I haven't experimented with the spacing to try and improve it either.

doppler (Rick) · #9 23-07-2017, 08:57 AM

Quote:

Originally Posted by Anth10

I'm still looking at getting one to sharpen up my shots.
Anth

Just thought I'd mention seeing that I'm on a tight budget I sourced my Baader OS. It was $265 including postage and 7 days delivery from the UK, a good saving on local suppliers. Probably even cheaper now that the AU $ is up.
https://www.firstlightoptics.com/com...ader-mpcc.html

doppler (Rick) · #10 23-07-2017, 11:21 PM

Did a star collimation tonight and I think that the stars in the corners have come up much better.

cometcatcher (Kevin) · #11 24-07-2017, 12:00 AM

Looks about perfect to me.

doppler (Rick) · #12 24-07-2017, 07:56 AM

I was real happy with it and focus was sharp, so I started an imaging run and guess what.... 6 subs in and damn Mackay clouds.

Here's a single 2min sub

Anth10 (Anthony M) · #13 24-07-2017, 09:26 PM

Rick, can't help the clouds, they seem to time there run for the new moon don't they? but hey you've fixed the scope alright. As Kev said - perfect as your going to get it I think. Well done. That's the benchmark set.
Thanks for your advice on the coma corrector question Rick and Kevin.
Keep up the fine work gents.
Anth