Astrophotography: A beginning.

[chupathingie]

…there are other ways than DSS to get that to stack. align_image_stack might register the images for you; then either a manual layering in PS or a command-line averaging would get you similar results. I was pleased to find that ais manages to do a reliable job of registering astrophotos.

[chupathingie]

This seems relevant here. It’s a big help to anyone under light-polluted skies. Old, but the info is still useful.

[fluffybunny]

This seems relevant here. It’s a big help to anyone under light-polluted skies. Old, but the info is still useful.

Excellent find,.. I had never seen it explained so simply before with a logical basis. Most of the time you see thumb rules and recipes. This was quite useful in the general sense.

[ravnostic]

I think, thus far, this is the best stack I’ve managed. Still working without flats nor biases, this is just reprocessing on a learning curve. But there’s some nice detail, more so than I’d gotten on the first go-round. Dust lanes, nebulosities, stuff like that. Stacking iz hardz.

http://fossilspringsaz.com/pics/2012/may/01/whirlstack.jpg

[chupathingie]

Ooohhhh…. that’s purty… You know, you’re gonna *have* to do flats sooner or later… you’ll get to the point where the vignetting drives you crazy! 😉

Lots of detail in that… I love how all the nebulae show up. How many subs? And what did you decide to stack with? Cropped? Full sized? Reduced?

[ravnostic]

Yeah, um, chupa about that…over on G+ Peter Bryant gave me some tips, and I applied them. Excepting the successful integration of flats (which had a dramatic effect on the resulting image…very little post processing needed, hell, I could have skipped it entirely), here’s the skinny: the best 18 of 21 subs (I call them ‘lights’), 8 darks (mastered), 4 lights (mastered), combined using sigma processing, full-frame, 50 iterations, processed mostly in DSS, with super-fine curves (I shouldn’t have bothered) in Canon’s DPP. Don’t know why the briht star flared when the others didn’t. I’d crop this if I were to use it for anything other then ‘gee, ma, look what I did’ posts.

Here’s the revised:

http://fossilspringsaz.com/pics/2012/may/01/whirl5b.jpg

[ravnostic]

err, 4 ‘flats’, not lights.

[chupathingie]

I wish I had some tools for doing sigma stacking. A straight-up average works, but doesn’t reject things like random noise spikes, satellites and aircraft trails… I need significantly more subs to get the same S/N.

Here’s where an actual telescope proves itself. While I’m waiting for the seasons to turn to bring large objects into view (most of which lie on the galactic plane), you have the focal length to tag smaller, more distant objects. Some astronomers call this time of year “Galaxy Season” for that reason.

[ravnostic]

A blessing and a curse, Chupa–with such a limited FOV, only 1/2 degree, I miss a lot. And while I can get close in, simple seeing conditions, at best, limit how small the stars can be, and how crisp the features. I think I’d do much better with wider FOV photography.

[chupathingie]

Yup… a trade-off, to be sure, but it doesn’t take much to bolt a rail on your scope to piggy-back a camera and lens… you’ve got tracking good enough for exposures at over a meter focal length, so a telephoto (or even a shorter standard prime) will just love it. Yeah, you’ll miss out on the pinpoint stars with the smaller glass, but there’s something to be said for a wide field; dust lanes and nebula complexes are usually on such a grand scale that <200mm is the only way to capture them without doing a panorama (which is on my list to do, though it's going to likely take a season of subs to pull off).

[ravnostic]

I’ve done piggybacking; I have a whole bungie cord system set up. I’ll have to dig some of those up; I think I got Orion’s belt area; I know I got constellation sized shots that aren’t stacked, just exposed for a while.

[chupathingie]

Had to revisit this thread, just ’cause I’m jonesin’ . You got a second body? Hell, do the twofer.

I learned a lot on my last attempt. Higher ISO+ more subs= fruitless. After a certain point, anyway. I shot a bunch of 2 minute subs at 3200 and realized quickly when I loaded up the stack that math and physics were not on my side in the quest to cancel noise. My S/N was horrible. Just so folks know, 3200 is too fast for a 5DII in this application. The noise is unpredictable at this speed, or at least control escapes me. I haven’t figured a way to subtract the extra noise from the dataset; taking twice as many subs at “too high” ISO is less advantageous then going longer at a lower ISO. IE, 60 1′ subs @3200 looks worse than 30 2′ subs @1600. There’s a trade-off there that I don’t quite understand yet.

[ravnostic]

Here’s the most recent stack; conditions weren’t ideal–there was wind, a haze from a dust storm the night before; the pollution from assorted state fires…but given all that, I think I did okay. The Eagle Nebula, home of the ‘Pillars of Creation”, which are more-or-less (ok, less) centered here. Hubble does it better, but I can’t be displeased. It’s at 1/2 res, so too big to post here. Linky:

http://fossilspringsaz.com/pics/2012/jun/18/eagleedit2full.jpg

Here’s a smaller version I can post here:

[lokisbong]

Damn!!

[orionid]

I said it on facebook, and I’ll say it here:
1) That’s farking amazing.
2) Details please?

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