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FORUMS Photo Sharing & Visual Enjoyment Astronomy & Celestial
Thread started 15 Jan 2018 (Monday) 03:32
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M42 - M81, M82, and NGC 3077

 
Roy ­ A. ­ Rust
Senior Member
Joined Dec 2015
Dallas, Texas
Jan 15, 2018 03:32 |  #1

Tonight looks like the last clear night for a while around here, so I set up my Orion Sky View Pro with my Tamron 150-600mm lens out back to take a lot of pictures of the Great Nebula of Orion (M42), and try to get some better shots of Bode's Nebula (M81) and the Cigar Galaxy (M82), while I had the chance.

Someday, I hope to figure out how to avoid blowing out the trapezium in Orion's nebula, or to fix it in post processing. But in the meantime, this is the best I've come up with, so far. I also need to make another trip to a darker site than my back yard - then I could probably get by with less than 151 exposures! Although, the more the better.

I stacked 151 images of M42, and 98 of Bode's Nebula with the Cigar Galaxy toward the bottom, and NGC 3077 as a tiny fuzzy object toward the upper right.

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Celestron
Cream of the Crop
8,435 posts
Gallery: 1 photo
Joined Jun 2007
Texas USA
Post has been edited 1 month ago by Celestron.
Jan 15, 2018 10:02 |  #2

Roy, nice job on the captures especially m42 . The secret tho to keep from having a blownout center on m42 us taking multiple short exposures from 5-15 sec exposures just to capture the trapizium . Then with the image you have above you can either add those during stacking or you can stack the exposures of the trap and then do a copy/paste of the trap on to the anove image . However when you do a copy/paste which can be done in PS , you can use the magic wand around the finished trap then right click and choose feather approx 2-4 pix then do copy and then paste on the original image . Feathering keeps the lines from showing up when pasting . It really is a simple technique and works wonders ! Look up Jerry Lodriguss and his website did have explanations how to do so easily .

Here's a link to the process above I told you about . Works very well !
http://www.astropix.co​m/html/j_digit/comp2.h​tml (external link)




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Roy ­ A. ­ Rust
THREAD ­ STARTER
Senior Member
Joined Dec 2015
Dallas, Texas
Jan 15, 2018 12:22 |  #3

Celestron wrote in post #18541315 (external link)
Roy, nice job on the captures especially m42 . The secret tho to keep from having a blownout center on m42 us taking multiple short exposures from 5-15 sec exposures just to capture the trapizium . Then with the image you have above you can either add those during stacking or you can stack the exposures of the trap and then do a copy/paste of the trap on to the anove image . However when you do a copy/paste which can be done in PS , you can use the magic wand around the finished trap then right click and choose feather approx 2-4 pix then do copy and then paste on the original image . Feathering keeps the lines from showing up when pasting . It really is a simple technique and works wonders ! Look up Jerry Lodriguss and his website did have explanations how to do so easily .

Here's a link to the process above I told you about . Works very well !
http://www.astropix.co​m/html/j_digit/comp2.h​tml (external link)

Thanks for the info... I'll certainly give it a few tries and see if I can master it... or at least novice it. ;-)a




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Pagman
I just hold the thing :-)
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Joined Dec 2011
Jan 15, 2018 21:35 |  #4

I was wondering the same regarding the blown out look I get of the center of Orion, no matter what I do in post, I can not bring it down, I just came to the conclusion it must be a lassive area of intense bright light.

P.


Olympus E-M1 and some Zuiko glass

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Celestron
Cream of the Crop
8,435 posts
Gallery: 1 photo
Joined Jun 2007
Texas USA
Post has been edited 1 month ago by Celestron.
Jan 16, 2018 08:22 as a reply to Pagman's post |  #5

There are 4 stars in the center that create alot of brightness throughout the nebulaes heart section , which causes blowout with long exposures . Short exposures of just a few section capture the stars but not alot of neb data . Therefore 30 or more captures of the center stars stacked will make a nice trap shot which then can be composited with the overall image . Just make sure when copy/pasting you paste the trap image ontop of the original image then adjust accordingly with PP . Look up M42 Trapizium only images and that will help you understand why you need seperate captures .

https://apod.nasa.gov/​apod/ap050710.html (external link)




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MalVeauX
"Looks rough and well used"
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Joined Feb 2013
Florida
Jan 16, 2018 08:39 |  #6

Nice grab! Composition helps too. You have the raw data in there, so you can practice processing it over time to try different things.

M42 is a very bright DSO, and is everyone's most common target usually because it's big, bright and easy to capture to an extent. But, it has a lot of dynamic range involved, from the very bright core (trapezium) to the wispy dust lanes surrounding it. To capture it all in a single exposure value, currently doesn't happen, due to dynamic range limitations (the difference of capturing the dust vs the trapezium is huge and overwhelming to the sensor, hence oversaturation occurring and clipping out all the data).

I used a similar approach that is described already, two sets of data, one for the core, one for the rest, and simply overlay the core and blend it in with masks, making a composite, but keeping all the data.

For mine, I used 30 x 180 seconds for my light subs for the nebula, dust and everything else (F6 ISO 800).
And I used 31 x 10 second subs for the core (F6 ISO 800).

The exposure difference is huge. 10 seconds for the core is all it took for me. And 180 seconds for the nebula and dust. That's almost 5 stops exposure difference (and each stop is a doubling of the exposure).

You can inspect how I blended my core & nebula here: https://flic.kr/p/Srjm​E2 (external link)

Very best,


My Flickr (external link) :: My Astrobin (external link)

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M42 - M81, M82, and NGC 3077
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