Horsehead/Flame colors

[dx_ron]

A "work in progress" post. I have ~2 hours of OSC data and ~6 hours with the AlpT filter. I'm hoping for rather a lot more of both, but the clouds and trees may have the final say about reaching that goal.

The AlpT filter will destroy the colors of the Flame, but I wouldn't expect it would work very well to bring in color with a mask and the Layers module. I suppose maybe I could make a mask for the Flame, but it seems the transition would be too obvious.

So I tried L+SynL, color from OSC using the AlpT as L. That seems promising, but what would you folks suggest instead?

B33_AlpT-L_OSC_color_test.jpg (482.94 KiB) Viewed 14605 times

One side-benefit is that Alnitak's extent is that of the narrowband, rather than the OSC version, which makes it look like a massive thermonuclear explosion (it is one, of course, but you all know what I mean).

[Mike in Rancho]

Good start! But yeah the Horsey I think might be a tough call. Personally I think the region looks best in RGB, but you want that big red wall back there, so seemingly NB Accent of Ha only would work -- IF it could leave the Flame alone. I wonder if it would.

There was a recent thread - maybe the HH w/ OSC, if anyone linked data? - but some duo-only data was warped into having a fairly orange Flame. But despite the end results, I think the means might have been questionable. Like, loading not as bicolor HOO and then altering up the "three" channels, if not outright protective or hue manipulative masking.

The only HH data I have is some old L-eNhance and not very long of it, so nothing I have really experimented with. The Horsey is on my list though.

[dx_ron]

I agree that RGB is the better way to go. Unfortunately, large chunks of OSC-worthy time are hard to come by for me for this part of the sky. What I really need is to get out to the club dark-sky site - but those opportunities are even more scarce this time of year. Work will be heavy until May, so I can only get away on a Friday or Saturday. I will probably have to make do with duoband data when the moon is out and hope to grab some more OSC before Orion starts the evenings behind the trees.

[fmeireso]

I tried it with L,RGB. Ha as L and color from an DSLR OSC

viewtopic.php?f=11&t=2752

i had about 3 hours of RGB and 3 hours of Ha data. It did come out pretty well ..I used a 90 mm scope. But it tends to go to orange
What scope did you use for this image?

But i just wondered...about midnight over here the street lights go out for energy saving. Maybe it is therefore i could get more data in a shorter period of time.

Youre picture looks allready pretty good though imho. You seemed to have tamed Alnitak quite well.

[dx_ron]

Yours is quite nice, Freddy. And yes, I should have included more details in my post. It was shot with an AT65EDQ (triplet objective, built-in flattener) and an IMX571C APS-C camera (RisingCam).

My issues with Orion as an OSC target include that it rises directly over a streetlight and goes behind a tree an hour or so after crossing the meridian.

The OSC in that image was 60s exposures, and processing just that leaves Alnitak totally out of control. An OSC-only image would require starting over with shorter subs. Using the HA/Oiii as L is what keeps Alnitak reasonable.

[dx_ron]

I'm back - with more OSC data. I halved the exposure time and started over on the OSC. Managed about 6 hours total. Nasty, nasty gradient between the streetlight and it never getting any higher than 48°. It kept coming out quite noisy (especially obvious once the Color module was reached), so I tried to be only as aggressive with Wipe as absolutely necessary - probably to the detriment of a truly flat field. More time will have to wait for next year, as the window will be barely an hour by the next new moon.

Color was interesting. I had to boost blue vs what either a star sample or full image auto-set. Turned the Bright Saturation way down (1.5 or so) in order to keep the flame from going all orange. I mean - there's nothing wrong with an orange flame, but I like this color better.

My attempt to add the duoband data as NB Accents destroyed the Flame, unsurprisingly.

The first image is from starting with the Autodev ROI on the Ha regions, the second is with the ROI squarely on the Flame.

B33_ST_v2.jpg (497.8 KiB) Viewed 14401 times

B33_ST_Flame-ROI.jpg (487.03 KiB) Viewed 14401 times

[Mike in Rancho]

Looking better I think! Slightly more cropped too?

I'm probably more drawn to version 2 here. Less foggy, and more crisply detailed about the Flame. Could maybe use a touch more deringing?

And yeah sometimes star color sampling can be a bit off, I guess it depends on the field. I'm pretty sure I need to feed more blue into my M81/82. Here, with a B-V of -0.11, Alnitak should probably be a good bit more blue?

My gradients of course get out of control at times, especially the L filter. I think sometimes, other than Basic with more aggression, the Uncal1 (despite being calibrated) can help me, if I then take aggression to about 60-65 but drop Falloff back to around 50 to keep a flat field.

[dx_ron]

Agreed - the 2nd one is better. That's the value in using the ROI on the part of the image with greater dynamic range rather than the overall-dimmer Ha region, I suppose. The extra crop was partly for framing (there's not a lot of interesting detail in the bits I cropped out) but mostly to give Wipe a slightly easier job.

I tried again with using the 6 hours of duoband data as L, but it didn't add nearly as much to the outcome as I had hoped. And it turned the Ha much more to pink, compared to using the OSC alone. Anyway, this is likely the extent of my data for this year so I will go back and re-do it, being more careful about the deringing.

[dx_ron]

Yet another version (this is what we do when we can't collect any new data...)

This time with the 6 hours of AlpT in the NB Accents slot rather than as luminance. It changed the Flame, but way less than I was afraid it might. At first I was worried about all the extra red showing up around the patch of reflection nebula just to the left of the Flame, but looking at some deeper RGB images on astrobin reassured me that it is real and would show up in the OSC data given enough time. Went back and forth between using pure red vs Balmer - this version is pure red for the Ha.

B33_ST_Flame-ROI_nb-accents.jpg (484.67 KiB) Viewed 14276 times

I also tried a version of Dietmar's trick of using HDR with only gamma highlights active to tamp down Alnitak, then a 2nd pass through HDR with gamma highlights turned off and light and shadow detail boost each up at ~36% for the Flame. Not sure if that's a technically legit way to treat the star or not, but it looks OK I think.

[Mike in Rancho]

Wow.

To me that's the best version of all these. NB Accent is really quite handy.