East and West Veil Nebula ini SHO

[Tommohawk]

All change for this one - new 61EDPH scope with flattener (I couldn't get a flat field with the TS72) new ZWO Mk 2 NB filters ( I got fed up with the huge haloes on the Mk1 version) and new software - AstroPixel Processor (I got fed up with the smeary effects I keep getting on DSS, (though to be fair it is free and seems to work well on everything under the sun (any sun) apart from the Veil))

I'd like to do a proper review of the 61EDPH, but I'll save that for another thread when I've had a proper chance to check it in more detail. One thing for sure is the field is pretty flat. 

I did this over several nights from the 1st-20th September - initially I anted to keep it simple and work in LRGB but was quite disappointed with that result, and so went with Hubble palette. 

I couldn't get DSS to deal with the processing - theres something about the veil that really throws it. I tried reducing the star count, change the flats, changing the stack settings - nothing seemed to work. So I'm on a free trial of APP - seems to work well, pretty intuitive, and stacks all channels from multi session much easier than DSS. Still trying to get the finer points sorted, one of which is how much to stretch it during the stack process. I went with the default and is seems pretty good, though the channels didn't seem very equal - tons of Ha which I guess it to be expected. Also I think my flats still aren't right so the corners have some odd colouration which I had to fiddle with in PS.

So - I stacked in APP, and just used PS to equalise the channels best I could. I tried reducing noise in the background, and also sharpening the detail a bit but the result didn't looks natural so this is just stretched and colour adjusted. The stars are a bit big - guiding wasn't 100% mostly because I forgot to rebalance East heavy after the meridian flip (Doh) - but I like the star shapes. I tried limiting the star numbers with a median filter in PS, but the result wasn't so nice - to my eye anyhow.

HEQ5, 61EDPH + flattener, ASI1600MM Cool, ZWO Mk2 NB filters (unmasked), Subs 300s with Hi gain (300) -15degC,  57xHa, 35xOIII, 26x SII. (No reason for the odd numbers - just the way it worked out!)

Seen better, but quite pleased with this so hope you like it - always happy to receive criticism!

 

[Tommohawk]

Thanks for the likes!

BTW one thing I meant to ask is whether or not the star colours look right - in general NB images seem to suffer with poor star colours, but this set-up/processing seems to work OK without separate processing of stars - any thoughts?

 

[carastro]

Great Image Tom all those hours have made it nice and smooth.  You won't get colour with Narrowband stars, well not true colour anyway.

My only comments are as follows:  as you asked me for CC.  Firstly - and I know this may be problematic for you as I think you are colour blind, so reds and Green I think are a problem, but the image is a bit green, and  there's a slight background gradient.  If you could get the colours right it would look even better.

Hope you don't mind but I posted a version that I tweaked to show you what I mean, but not sure if you'll be able to discern the difference. 

Carole 

Edited October 12, 2019 by carastro

[Tommohawk]

Hi  Carole - thanks for that... and I can see the difference!

You are right, my colour vision is a problem, and this has caused me issues with RGB imaging because I can't easily tell if there's green in the final image. I've learned to run the PS "eye dropper" tool over the final image and use HLVG or similar.

However, in Hubble palette SHO I find myself in a quandary because the fact is that an image rich in Ha will show as green in the final image, and although this may not be aesthetically "nice" it is the true result, albeit false colour. (Can we have a true falsehood!?)  I found an interesting thread on this by Graem Lourens and he makes a similar point - with  super images too.

I think with my colour vision being iffy the green doesn't look so "wrong" as it does to someone with accurate colour perception. But as Graem suggests, if you want correct "data" maybe some green should stay?

The Veil has always given me grief one way or another - I might have another go in HOS or something, maybe that would look better.

Returning to colour vision issues I should point out that, at the risk of seeming pedantic, I have colour vision deficiency and am definitely not colour blind. Complete colour blindness or achromatopsia is quite rare and has an incidence of about 0.002% of the population, whereas colour deficiency affects about 7% males and 0.5% females. 

In my case this means if greens and reds are either faint or small (eg red berries on a tree) I can't discern them, but if more saturated and/or in larger blocks, I can see them OK.  

Thanks for the feedback and reworked image!

[Tommohawk]

OK well here's a slightly reworked version - TBH I did this mostly just as an exercise to test the new Astro Pixel Processor software, and having done it thought I might as well post it. I reduced the green channel in the integration and also used a superluminance layer composed of all SHO data.

Seems to have made the stars a little smaller, and a bit more natural colour maybe but not sure if this is the effect of the luminance layer, or just because it was a complete rework. 

Anyhow, whilst doing all this I have got to like APP software and have splashed out on a 12 month rental license. I'd quite like to do a review of APP at some point which might be helpful - I can't claim to be a "power user" but more from a new users perspective.