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Old Data - "What to do about Alnitak..."

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I've been sitting on this data for quite a while (it's from Jan 2017). I've had a few goes at trying to process it, but always junked the results - mostly because of Alnitak! :undecided:

I've bitten the bullet and just posting it here to try and draw a line under this lot (and I've not done much else recently - illness and summer light nights...). Flare and scattered light in the field hasn't helped me and there's a bit of fringing with the brightness of the star. I have since cleaned the objective on the FLT110 as it was filthy, and I may have struggled with transparency, but I'm not sure what else I could do here to bring out more detail or contrast into the image with Alnitak sitting in the field - it just feels a little "soft" ?‍♂️. It also throws the colour balance off a bit - I think this is an Ok version, but the Flame is perhaps a little on the red side.

Details are:

ST2000XM + FLT110 (with FR at f5.6).
LRGB : 29x5m, 25x5m, 17x5min, 15x5min (RGB 2x bin)
Captured Jan 2017

C&C welcome...



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I seem to recall a P'Shop tutorial on this by Rob U235, a while ago  now so may be old age playing tricks on the brain.

Will have a search.


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Thanks - useful tutorial! Though, while I can shrink Alnitak down (to a point - it's horribly blown at the core: I think I would specifically need shorter exposures to deal with the core of Alnitak itself), I'm not sure I can use the same tutorial to deal with all the flare around the star. It is a tricky one, probably not helped by my setup here: the FLT is good, but a lot of glass (with the focal reducer in train too) and probably not quite up to the control of say a Tak, or a reflector here.

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5 hours ago, coatesg said:

I have since cleaned the objective on the FLT110 as it was filthy,

In the "good old days" of film photography, one method to achieve a soft focus effect was to put a little vaseline on a clear filter and place that in front of the lens. The vaseline scatters some of the light, decreasing contrast. Any filth and grime on an objective or primary mirror has the same effect: it reduces contrast and smears the bright light from a star in the surroundings. If you want to capture nebulosity or a galaxy near a bright star, you need to have clear clean optics for best result.

In your case, I think I would actually keep the image the way it is, and accept the fact that Alnitak is a very bright star surrounded by nebulosity.

Btw, you captured some of the fine dust in the Horse Head, it's no longer a dark shadow in front of the Ha field. I like that. But the image may work better when rotated 90 degrees counter clockwise.

Edited by wimvb
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Thanks Wim - yep, definitely cleaner optics would have helped, though the Thames Valley is not reknowned for the clarity of its skies! 

I'm taking it for what it is, I'd like to have another go at this later (possibly with different kit), and with multiple exposure lengths, and bringing in HA data, but it is what it is at the moment. And yes, Alnitak is bright ?

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1 hour ago, wimvb said:

But the image may work better when rotated 90 degrees counter clockwise.

Looking at it again, I agree!


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Yep - not sure why I never grabbed HA for this really - It'd probably bring Alnitak back a bit, but possibly to detriment of the Flame and NGC2023 - guess it'd depend a little how the merge was done.

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