M81/M82

[dx_ron]

I think I'm done collecting M81 data for this year, time to move on. This stack is 11:45 of OSC plus 9:15 Ha (from the duoband, so quite inefficient vs proper mono).

M81_OSC+Ha_v2.jpg (454.13 KiB) Viewed 3370 times

Not yet totally ready to call it done in terms of processing (mostly because it is both cloudy and full moon), so no link to better version at the moment.

Part of the curse of living on the B6/B7 border is that 12 hours at f/7 is just barely enough to start seeing hints of IFN. Which is a problem, because "hints" of IFN just look like crappy noise, and pushing that back into the background also pushes Holmberg IX with it. I've tried a couple of ways to bump it, but so far have not found one that doesn't mess up other parts of the image.

[edit - some capture details]: AT130EDT, SkyRover 1.0x flattener, Astronomik L3, Risingcam 571c for the broadband, replace L3 with Optolong L-Ultimate 3nm duoband for the Ha. 470x90s OSC, 111x300s Ha

[fmeireso]

Very nice , you can definately see tha Ha regions, especialy in the 'cigar'. I always forget if this is M81 or M82. I resemblens my image at time. But i needed Stefans help to get the Ha regions out.

Nice job indeed.

Cs
Freddy

[Mike in Rancho]

Everything seems quite clean.

Plenty of integration, so it should, though I imagine the F7 requires it also. With so much Ha, I imagine you could go stronger (or redder?) than the light touch you used here. But, matter of taste and it can easily overwhelm. M82 looks sharp.

I went back to check my last M81/82, which was only 5 hours so pretty dirty, and seems I also suppressed whatever IFN was picked up, and just had the little knots of Holmberg IX floating there also.

That pesky IFN!

Not sure if there's anything to be done, depends on the extent and the scale size if you stretch it out. Since we were recently discussing it, is H-IX larger than the bits of noisy IFN such that large scale sharpening, perhaps with several of the small scale wavelets zeroed out, would enhance only H-IX?

After which, you could then go squash the IFN back down with a gamma reduction in a post-tracking FilmDev, or with the gamma control handily included in NBA. Or even SS.

[dx_ron]

That "light touch" with the Ha was actually something like 170% strength in the accents. Remember, this is Ha through a Bayer filter, so my 9 hours is equivalent to what you'd get in about 2 hours 20 minutes, with your fancy-pants mono setup. Bear in mind also that I have absolutely no idea how choices I make in the optidev phase of the accents module affect the result.

Spent some time today redoing it, trying to maximize IX. A bit different RoI, a touch of gamma shadows in HDR. I think that was a poor choice, but I'd never used it before and it did bump up IX. A fairly heavy hand with Sharp, including even a 2nd round with just the IX region - but not quite your idea. I'll try that. Finally just a touch of Isolate (25%) to knock the background noise down (and so I also backed off from the defaults in NR).

It really muddied up M82, but Holmberg IX stands out better. So, yea?

M81_OSC+Ha_v4_IX.jpg (471.5 KiB) Viewed 3275 times

[Mike in Rancho]

Oh. Cough cough. I think you are right.

Granted I am an aficionado of dark backgrounds, but even beyond that I think edit #1 is the clear winner, though yes H-IX pops more in edit #2. I guess more faint stars are showing too, and I like that, but ouch that bright purple sky. And the main targets aren't as crisp or clean anymore either.

Holmberg IX might just have to be written off as not deep enough, despite all these hours accumulated, for the better overall good.

170 NBA strength was it? Wow. I am having a mild sense of deja vu, however.

I'm trying to remember a similar conversation, also about M81/82 and NBA, maybe with Dietmar or Stefan. Or both. What I think I was generally doing, since this was for galaxy Ha knot boost rather than nebula boost, was to go pretty severe on the NBA OptiDev screen using ROI, threshold, IFD, and shadow linearity, so that just the knots showed in M81 (plus a central disk or donut but what can you do?), and the burst of M82. Everything else was pretty blacked out.

But then in NBA screen 2, galaxy preset, there was a tension between the M81 knots and the M82 burst. Using brightness correlation and detail size adjustments, things were good for one or the other but not both at the same time. So finding the right compromise was difficult.