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Old 27-08-2009, 09:48 PM
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Tarantula from Astrofest

Continuing with the Astrofest theme....My latest processing efforts ...."Tarantula from Astrofest" (Friday night this time).

This image is a stack of 5x3min and 6x4min subs at ISO800 (with ICNR and flats) through the 400D, paracorr and Newt.

Having seen red versions of this object in other posts I'm not sure if the colour is correct but that's how it came out of the camera?

Comments/tips etc welcome.....
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Old 27-08-2009, 09:59 PM
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ozstronomer (Geoff)
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Peter,

Great image- my preliminary processing has come out with a similar color range. I understand this may be due to the camera be unmodded.

Geoff
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Old 27-08-2009, 10:01 PM
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Beautiful shot. Looks almost O111
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Old 27-08-2009, 10:10 PM
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Wow! Peter, that's just so nice.
Love the colour.
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Old 28-08-2009, 06:39 AM
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Thanks Geoff, Dave and Jeanette.
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Old 28-08-2009, 06:44 AM
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I'm loving your DSLR shots mate. Great.
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Old 28-08-2009, 08:32 AM
dpastern (Dave Pastern)
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Good shot, I also like the colour. Green is so much nicer than Red imho.

Dave
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Old 28-08-2009, 09:55 AM
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I just spent a few hours with NGC 2070 too - my shots are a similar jade colour - I'd love to know how folks get the reds (and maintain colour fidelity) that seems to elude me on this target!

Very nice shot,

Matt
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Old 28-08-2009, 10:13 AM
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Pretty sure it's a result of unmodded DSLRs cutting a lot of the red end.
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Old 28-08-2009, 04:26 PM
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Quote:
Originally Posted by troypiggo View Post
Pretty sure it's a result of unmodded DSLRs cutting a lot of the red end.
So why do other red objects like catspaw and lagoon come out red with the same camera?
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Old 28-08-2009, 04:28 PM
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nice very nice - but a tad too many green stars
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Old 28-08-2009, 04:39 PM
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Great shot Pete.

The red is definitely difficult to bring out using a DSLR. I think you will find that many of the "red" ones are done using RGB imaging.
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Old 28-08-2009, 06:01 PM
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Quote:
Originally Posted by peter_4059 View Post
So why do other red objects like catspaw and lagoon come out red with the same camera?
You know I don't know the real answer to that, but I can make wild and crazy guesses...

... unmodded DSLR shots I've seen of Cat's Paw, Lagoon, even Eta Carinae also aren't really red, they're kind of purples.

Maybe those nebulae are emitting slightly more in the red range, and Tarantula is emitting more outside or beyond that range and we're only seeing the blue-green parts more dominantly?
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Old 28-08-2009, 06:23 PM
dpastern (Dave Pastern)
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I believe that that is the issue Troy/Peter. Remember, light is at various wavelengths, and not every object in the night sky has the same emission characteristics. Lagoon etc might be quite strong in the Red zone, and in a part of the spectrum that DSLRs unmodded sensors can detect the Red. Tarantula is probably stronger in a different part of the spectrum.

Dave
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Old 28-08-2009, 07:23 PM
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Quote:
Originally Posted by peter_4059 View Post
So why do other red objects like catspaw and lagoon come out red with the same camera?
Hydrogen alpha emmissions are in the red end of town, your oxygen 111 are in the blue/green, both being emmisions, your reflection nebs are scattered blue light and some of the darker dust will be into the browns.

the colors of various objects will depend on the type of light coming from them combined with the cameras ability to handle those same wavelengths.

An unmodded DSLR does not have a high response to the red Ha so its diminished , if you shoot the cats paw, it really only emits in the Ha so even with DSLR you will get reds (not a lot) the same goes for the horsehead,

however some objects (in this case we have the tarantula) there is a high amount of the O3 possibly also some reflection in there too, in an unmodded camera this will swamp the little red you have, and voila a blue tarantula.

Some objects have a combination of both and as a result red plus blue looks purplish, you will find this in say the Carinae Nebula.

there is no wrong or right, its just what your camera percieves. Insects see well into the ultra violet and probably see everything different to us completely. there has been much perhaps condescending talk about unmodded cameras. i personally dont care, blue/red whatever its just that part of the spectrum you have captured.

enjoy thats what counts.

clive
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Old 28-08-2009, 07:27 PM
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Nice Tarantula Peter, The blue is a result of using an unmodded DSLR which is quite sensitive to OIII and not so sensitive to the overpowering Ha which shows as red in modified cameras.
Nice detail, guiding and processing.
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Old 28-08-2009, 08:05 PM
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Thanks everyone for the comments and explaination regarding the missing red. The strong OIII/weak Ha makes sense. I'll have to look out for some shots of this through a modded dslr.

Peter
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Old 28-08-2009, 11:47 PM
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Well what'dya know? I guessed good. Me smart. Me go play toys now.
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Old 29-08-2009, 12:09 AM
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Octane (Humayun)
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Peter,

That's a great shot. Very, very smooth. I like it.

Regards,
Humayun
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Old 02-09-2009, 05:50 PM
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Just catching up on posts here - thank Humayun.
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