M20 Trifid TEC180 now fluffily repro'd

[gregbradley]

I took this one on my last dark site trip. Acutally conditions were not that great, it was very windy and seeing was OK as a result. Later nights were sensational but this was taken on the first night when it was very windy.

Always a favourite, the Trifid Nebula. Now reprocessed to retain the fluffiness of the nebula and reduce the overexposed heavy contrast look.

TEC180fl, FLI ML8300, Tak 4 inch .75X reducer giving F5.2! Tak NJP mount, MMOAG offaxis guider. Its like a 180mm FSQ!

http://upload.pbase.com/gregbradley/image/134574410/large regular

http://upload.pbase.com/gregbradley/image/134574410/original large

Greg.

[renormalised]

Very nice :)

Only one pick....the red part of the neb looks a little overexposed, a bit too bright.

[Gem]

Wow! Very nice!!!

[gregbradley]

Thanks for that. I had already pulled it back down with curves. I pulled it down some more.



Thanks for that.

Greg.

[atalas]

Nice shot Greg....whats all these 8300 shots?you tied of your big chip camera? would of thought the small pixels of the 8300 would be good match for the FSQ.

[Octane]

Greg,

That's some serious image scale. Looks like a brilliant scope.

I have to say, I think you've been a bit heavy-handed with your processing. To my eyes, at least, there is just way too much contrast. So much so, that your background appears to be clipping into the black. It probably isn't, but, it just appears that way (using a calibrated screen, here).

I think you can still retain the punchiness in this image, but, still keep it light and fluffy, by reducing the amount of contrast which is forcing the background into black.

Light and fluffy trifids are delicious. :)

H

[irwjager]

Lots of life in that one Greg! I actually quite like the way you processed that. It's bright, sure, but detail doesn't suffer and you get a real sense these objects glow (it's all too easy to kill that when processing). Nice!

[DavidTrap]

I'm going to vote with the overexposed camp here - it's just too in your face for my liking Greg.

I'd really like to see if the details comes through in a toned down version.

DT

[gregbradley]

Thanks Louie. The 8300 chip would be good on the FSQ. I'll have to give it a go.

I'm in 2 minds about the 8300 chip. Its got good sensitivity, I like the image scale it gives but the small wells give you bloated bright stars.
So 5 minute exposures for LRGB and 15 minutes for narrowband seems to be the formula. I've got my eye on the new KAI29050 chip but it has even worse well depth at only 20,000 electrons. The 8300 is 25,500.
I have been using 10 minutes and only recently decided its a mistake and 5 minutes would be better. Noise is so low that multiple short exposures is fine.



Point taken. Its now repro'd. It went off the rails somewhere in the earlier processing. Now light and fluffy and a bit wider field. I like the way it picked up some nice reds in the background. The background looks nice whereas usually the background with the Trifid is usually yuck.



Thanks Ivo but with the fresh eyes of the group I can see I missed the boat with this one and I repro'ed it.



Repro done. I agree after seeing the posts I'd lost control of the processing at some point.

Its pretty amazing though to overexpose a dim nebula with only 1 hour of luminance and 10 minutes each of RGB! I guess that's the power of 180mm of fluorite, F5.2 and 60% QE of the FLI 8300 at -45C brrrr.

Greg.

[irwjager]

Looks like I'm in the minority. :) I still prefer the previous version, which looked just fine on my calibrated screen (absolutely no clipping and plenty of background level). The faint background Ha in the original was perfectly red whereas it is now orange (checked RGB values), same goes for the stars which very closely followed black body RGB values in the original (http://www.vendian.org/mncharity/dir3/blackbody/). In the repro, stars that were previously red are now orange (again, checked RGB values).

But, as, Rogelio Bernal Andreo says; "There are as many schools of astroimage processing as there are astrophotographers." :P

It's a fine image regardless! :thumbsup:

[gregbradley]

[QUOTE=irwjager;722166]Looks like I'm in the minority. :) I still prefer the previous version, which looked just fine on my calibrated screen (absolutely no clipping and plenty of background level). The faint background Ha in the original was perfectly red whereas it is now orange (checked RGB values), same goes for the stars which very closely followed black body RGB values in the original (http://www.vendian.org/mncharity/dir3/blackbody/). In the repro, stars that were previously red are now orange (again, checked RGB values).


OK, I posted a few minor tweaks to make those background reds more red and a minor tweak. Its somewhere between the original and the 1st repro.

Greg.

[irwjager]

Nailed it!

[gregbradley]

Thanks Ivo. I aim to please!:lol:

Greg.

[Ross G]

A fantastic photo Greg.

I love the colours and the detail.

Thanks.


Ross.

[gregbradley]

Thanks Ross. I originally intended to do multi hour RGB with that and extra luminance. But my laptop had bogged down with a failed auto Windows update. It stopped imaging twice at 3am. On checking it out more thoroughly (I at first thought the power supply cable pulled out of the filter wheel) it turned out in Control Panel/windows update that it was set to install updates at 3am, they would fail and it would restart the computer. This interrupted the imaging run.

So I lost about 5 hours of imaging time.

I am surprised the RGB data was so strong for only 10 minutes. That's the F5.2 for you.

Greg.

[strongmanmike]

I like the brightness, the main nebula is significantly brighter than the surrounds so how you have presented it is probably quite right. I think the colours are pretty well spot on too, I'd like to see a tiny bit of torquoise green in the outer dusty bits if it's there but it still looks very nice regardless :thumbsup:

Don't you hate hardware problems in the middle of the night!!

Mike

[gregbradley]

Thanks Mike. Perhaps the use of the HLVG plugin may've taken that slight green hue you mention out. Generally green is an unwanted shade in astro images but yeah in dust I think you are right it has its place.

Greg.