Good Old M20 - Trifid

dcalleja · #1 10-06-2007, 06:28 PM

Hi all
Heres my first LRGB attempt at the Trifid. Not enough time in the exposures and I couldn't seem to get the colour balance right. This is at prime focus of my 8" LX200R @ f6.3 using a DSI PRO II.

Let me know what you think - criticism is welcome.

leon · #2 10-06-2007, 07:23 PM

Dan, for a first attempt you have have done a great job, well done.

Leon

dcalleja · #3 10-06-2007, 07:29 PM

Thanks Leon. Still getting used to the new LX200.

leon · #4 10-06-2007, 07:33 PM

Yes Dan it takes a while to get used to using your gear, I'm learning new stuff every day, but isn't it fun

Leon

Bassnut (Fred) · #5 10-06-2007, 07:42 PM

Dan, nice detail, but theres something astray there, the RGB subs look the same, is this a true RGB combine?. Scuse my ignorance, did you take 3 sets of subs with RGB filters, or a single colour shot?.

Fred

dcalleja · #6 10-06-2007, 07:48 PM

Fred
Yes - I used the three filters I got with my DSI Pro II and did the L using the infrared filter. Combined and aligned them in Photoshop. I used a technique I saw on the web somewhere. Select one image (Red say), select the blue channel in Photoshop and copy the blue image into that channel. Then do the same with the green (but in the green channel). Last step is to layer the L in as a separate layer and select Luminance in Photoshop.

I've always had some troubled doing this technique (all 3 times) and I'd be interested in knowing if theres an alternative?

Bassnut (Fred) · #7 10-06-2007, 08:13 PM

Dan, for a start, can you post the 3 RGBs here seperately?.

dcalleja · #8 10-06-2007, 08:23 PM

Fred
I've saved them as JPEG from the original TIFF to upload them. Thanks

dcalleja · #9 10-06-2007, 08:25 PM

Fred
I should have added the one not labeled RG or B is the L image.

Dr Nick (Nick) · #10 10-06-2007, 09:06 PM

Very nice, I think a few more exposures would have helped though.

Bassnut (Fred) · #11 10-06-2007, 09:30 PM

Sorry Dan, Nicks right, theres almost no Green and Blue data, its mostly noise.

You didnt say what your exposures were. Anyway, you need like 10 times more at least.

dcalleja · #12 10-06-2007, 10:42 PM

Thanks guys I think you're right. These were 15 or 20s subs. About 20 as I recall. Whats the right ratio to use ie: L to R,G & B. Do you typically need longer exposures in G & B as opposed to R?

atalas · #13 10-06-2007, 11:12 PM

Good effort Dan.

Ric · #14 11-06-2007, 01:34 AM

Hi Dan, thats a nice first image. The 15-20 seconds subs is okay if you are in Alt/Az mode but you will find it helpful to increase your number of exposures to at a minimum of 50 at least. I try to aim for around 100 - 150 exposures.
With 20 exposures I think you would be missing out on the fainter detail.

It is still a fine effort though

dcalleja · #15 11-06-2007, 01:05 PM

Thanks guys
I'll have to do some more research on this. I suspect the ratio of R to B to G must have to be different as all my R efforts always show more detail than either B or G. So I'll try much longer exposures (more subs) regardless and also try more still on B & G.