I suspect it's actually M8, not M20. The bright area in the middle of the nebulosity looks like the Hourglass Nebula combined with a nearby star.
I think you're probably seeing a variety of problems combined: lack of guiding, maybe some sensor tilt, poor focus (despite the Baht mask) and probably a reducer that isn't doing a great job. You'll need to fix all of these to get a great result but you could chip away at them one at a time and get some improvements.
Definitely out of focus, so either you used the mask incorrectly, or the
focus setting changed before the first exposure began, or the mask is for
a different size scope.
Your scope is not that fast, even with the reducer, so longer subs are required,
at least 30 secs, preferably longer
raymo
Last edited by raymo; 11-10-2017 at 01:19 PM.
Reason: correction of error.
Looks like the Lagoon (very close to Trifid). Are you doing this live or post-processing? It looks like live stacking?
Its been a while since I've done live stacking with an ASI224MC on an 8" SCT - so take this with a grain of salt.
What are you using for stacking? Sharpcap is good for this. I know it sounds odd in terms of imaging - but try shorter subs and lower camera gain - and stack more of them. It will stop that star bloating and saturation. And when stacking muck around with the histogram - you will be surprised what you can pull out of what you have. Have a look on youtube at things like this: https://www.youtube.com/watch?v=AcRc1LRq6Ms https://www.youtube.com/watch?v=O6n2z6rj_98
Also, cheapo x0.5 reducers aren't great on an 8" SCT so that might be adding to the problem (this is probably adding to the uneven field illumination you are getting there). But you do need focal reduction to get it fast enough for alt-az and to get a big enough field-of-view. If you are using sharpcap you can also make flats beforehand and while stacking it will correct for the uneven illumination.
I used to use sharpcap - with 2-5secs subs at gain300 and stack 20-50 of them. Also the SCT focal reducers are better (and you have to get the camera-focal reducer distance sorted) - but see how you go with what you have first. And sometimes a UV-IR filter to reduce star bloat helps.
Yes, I think Rick is right, looks like the Lagoon.
But on the issue of making it better, here are some ideas:
1. Do NOT use a SCT as a beginner imaging scope. F10 is far too slow, and the long focal length requires careful guiding. The 0.5X reducer isn't a great match to your scope so probably didn't help much.
2. A fork mount is not suitable for long exposures. You need 3-5 mins subs to tease out the details, even for bright objects like the M8.
3. More subs. Depending on the object, you need at least 30 mins (10x3 mins) to get some the fainter stuff out, 2-4 hours would be better, but that requires good initial alignment, good EQ mount, good guiding, longer subs etc...
All in all, it's a great start. But if you want to do more AP work, get a small APOrefractor of f7 or less and a FL of 400-600mm, which will give you a larger imaging area but also much more forgiving in terms of guiding errors etc.
Hope that helps.
Bo
Here' a single frame I took back in 2011 when I first started posting.
It's 130 seconds so I think I was on a wedge but unguided.
Taken with an lx90 8 inch no FR F10.
I think the focusing is better but it's an ACF so may have more effect - not sure.Canon 450d.
No flats no darks - just the one frame
I used sharpcap to get the image and DSS to stack them....
I have a .63 sct reducer, and will give that a go with both longer
and shorter subs as suggested.
(the .5 came with the camera and is easier to set up so....)
the mask is the right size - i get pretty good results using
this same setup for planetary (minus the reducer)
I also tried focussing by sight - same result
One more question: Does sharpcap live stacking account for field rotation?
I'll just have to pray to the weather gods now to give all your suggestions a go. - thanks again
As my pic is without a reducer, I'm wondering how your pic is with one, as the field of view appears smaller ie more magnification not less
i know this one!
the 450d imaging chip is much larger than the chip on a Zwo 224...
so the apparent image almost covers the chip on my camera,
where it only lights up parts of yours....
Yes sharpcap will account for that. If you just want quick live pics give it a go, many use live stacking with software like sharpcap on alt-az mounts (really short subs).
If you want nice images, your setup needs a big rethink as suggested by the other posters who know what they are talking about (unlike me).
