Eta Carinae - Canon/SBIG ST-8i

[Omaroo]

This is the result of 43 stacked frames from my 350D - ranging from seconds to minutes and over several months'-worth of sessions, merged with the monochrome frames I took recently with the SBIG ST-8i for a little extra luminance. Detail is starting to show quite well, but I've left it in a high-contrast state to highlight it. Now's my chance to really knuckle down and take some really long exposures and get as much data as I'm comfortable spending an afternoon dealing with. :thumbsup:

All done in Photoshop CS3, including merges, stacks and hand-alignments.

Slightly higher resolution version here: http://www.omaroo.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=5768&g2_serialNumber=2

Second image is an HDR merge of the same source files minus the SBIG frames - hence the larger FOV.

High-res version here: http://www.omaroo.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=5773&g2_serialNumber=1

[leon]

Chris, nice going especially combining all those different length frames, ;) may I say though I'm not quite sure of the colour range, especially the very dark ones in the middle of the object, however plenty of detail.

You must have had quite a work load compiling all those shots.:eyepop:

Leon:thumbsup:

[Omaroo]

Thanks Leon :)

Yeah - I wish I had a reliable reference for colour of these common objects. Everyone has their own idea and it'd just be nice one day to start doing them all in the hubble pallette - as soon as I get an O-III, H-a and S-II set. This way I'll have a real reference that I can relate to.

[CoolhandJo]

I like these colours. Blue looks quite different for this Nebula. Also, the different cameras seem to have brought out sublte detail not ordinarily found in OSC sessions.

[Matty P]

Excellent image Chris. Lots of detail coming through. Definitely worth the effort combining the images from both cameras.

What is the total exposure time?

:thumbsup:

[Omaroo]

Thanks fellas :)

Matty - it's hard to tell because I've somehow managed to knock the EXIF data off most of the source frames. I estimate about 3 hours though.

[h0ughy]

looks as though you have been enjoying yourself Chris

[ejcruz]

Great capture and processing that luminance really bring's out the details.

Eddie

[spearo]

superb, especially the first one
frank

[AlexN]

Nice easy way to get RGB into your heavily detailed monochrome ST8 shot!!

I like it a lot...

[Kevnool]

Superb detailing Chris, once again i,m impressed.....cheers Kev.

[Omaroo]

Thanks David, Eddie, Alex, Frank & Kev :)

Can't wait for a filter wheel Alex, but this will do for the moment! For this one I took each and every image in TIF format that I had on my hard disk that was any good - no streaks, focus OK, no star trails, etc, etc and loaded them all into a folder. They came from several nights-worth of shooting and from the 350D in combination with both my C-8 and FS-102. They were all at full resolution (3456x2304). The ones I took from the ST-8i the other night were at 1530x1020.

Then groupled them into stacks of four images, and loaded these into a CS3 stack (files/scripts/load files into stack). For each of these stacks of four images I produced a second mean-stacked image and then adjusted shadow/highlight before saving it. From the 40-odd original images I was now down to 10 - plus the SBIG lights. I then divided these 10 into groups or 3,3 & 4 and did the same again. And again to get one final image that was looking pretty darn smooth. I then repeated the process yet one more time with the SBIG lights - and these resulted in a huge crop as the FOV was far smaller, of course. When these were stacked and merged the detail started to really pop. It's so hard not to try and over-process it.

Anyway - more to go yet. I'm still getting different results as I'm also trying to merge the larger groups into a better HDR image. I'll post it when I'm happy... LOL!

[AlexN]

sounds indepth... And obviously works well!!

[strongmanmike]

That's a great way to save money too ie take the colour with the DSLR and then use the high res lum from the ST8. The RGB is the least important and very forgiving. I have had great success with crap RGB ie too little exposure and out of focus, you can blur it, minimise it chop it up into little pieces and even fry it :scared: etc, as long as the Lum is excellent you can compile a good colour image. This is probably quicker too as its only two exposures instead of 4 needed for the LRGB technique :)

I took this 80ED data using a small chip CCD (equivalent res to a DSLR through a much longer FL I guess)

http://www.pbase.com/strongmanmike2002/image/57081518/original

blured it and used it as the colour for this image which took advantage of the high res Lum through the Starfire:

http://www.pbase.com/strongmanmike2002/image/96166688/original

Not ideal and I plan another smash at NGC 253 this year with better RGB but still a good result.

Nice Eta too, are you getting focus shift across the frame due to image plane tilt?

Mike

[Omaroo]

Thanks Mike - and a nice explanation of your technique!

Yes, the images were far from great and I am getting differential focus across the plane. I'll sit down and get some better examples to work with and try doing it seriously next time around.

:thumbsup:

[jase]

Good to see you getting a handle on the ST8 Chris...and a little ingenuity in adding some RGB to the mix. Look forward to seeing more.

[Omaroo]

Cheers Jase - thanks a lot! :)

Lots of fun coming up - only clear weather required!

[Octane]

Chris,

Looks like someone smashed a pomegranate on my monitor. :D

Beautiful work. The process of combining so many images of differing exposures file by file in Photoshop is worthy of a medal! Is there any particular reason you don't use astro-software dedicated to the purpose? Or, is it that you're just comfortable with Photoshop and know the results you'll achieve? My very first M42 was painstakingly put together in Photoshop CS, layer by layer, using difference as the blending mode. I'm not sure if it had a stacking/alignment routine. But, anyway, the image turned out pretty drastic with loads of field rotation. Glad to see things have much improved!

Regards,
Humayun

[Omaroo]

Thanks a lot Humayun for the kind words. :) We all like those from time to time. :thumbsup:

Yes - I'm pretty comfy with Photoshop. I've been using it since v1.0 in 1990 - but under the tight contraints of a pre-press environment, where accurate, calibrated CMYK separation for press was more important than how it looks on a monitor or web page. This is a new use of it for me, more akin to the creative duties that Photoshop may get used for in an ad agency rather than for straight output to film via a RIP/imagesetter.

I kind of find it a bit like a swiss army knife - it's got all the tricks on board, but they're folded up and aren't labelled "use me for this". Photoshop will do anything a dedicated astro program will do - but I guess that it's like driving a manual rather than auto. I absolutely agree that the dedicated programs are more suitable for astro use though, in the long run. I already have Images Plus but quite frankly can't sit through those damn awful training videos! :lol: