[Bassnut (Fred)]

Originally Posted by CoolhandJo

Fred, it seems to me that no matter what camera you were using the images would be pretty good. This is one example (I like the first image best)

Thanks Dr Paul, the 40D allowed the nice pic, no more difficult than a CCD in this case.

Originally Posted by h0ughy

that's really interesting, i thought the combination would have been a lot better?

So did I David, was more obvious with the CCD, its possible though that it was just the Ha was not as good as it could have been. BTW, since I thought the RGB was initially Ha (I forgot to put the filter in), it was taken with moon up, and yet it was of good quality, without flats. And there was more RGB data than Ha, arse about.

Originally Posted by multiweb

I like the HaRGB better coz it's got way more details and contrast in the neb. Have you thought about blending the two finals in PS? Maybe use the HaRGB as greyscale Highpass, see what happend to the RGB if you keep it as base. Maybe you get the best of both worlds with a bit of masking?

I played with the two layers and attached the result. RGB as base, HaRGB as 26% opacity highpass 60px and one more HaRGB on top as Lum Opacity 70% with a star mask from the RGB layer.

Excellent work there Marc, I lined them all up side by side and your blend is the go. I didnt attempt that to show the difference, but will now. Ive never done that with the CCD, didnt need to, the Ha was OK, but Gregs recent blend has shown some advantages too so I will try that. I didnt bother with muliple layer masking this time, thinking it was all just a quick poke, probably did myself a disfavour.

Originally Posted by telecasterguru

Fred,
I also like the Ha but only because of the greater detail. The RGB is very smooth.
I think that the comparison of DSLRs and CCD imagers is a very informative as well.
It has made me think about my next imager as I currently use a 1000D but want to move to a more specialised camera.
Not sure that about the outlay as compared to the results.
I would like to see a few more comparisons between DSLR and CCD cameras.
Thanks for the fabulous images.

Frank

Thanks Frank. If you mean by specialised an Astro CCD, for bright objects on a wide field scope, a modified DSLR gives near CCD performance with very high res for MUCH less dollars. For narrowfield and or dim objects, CCDs really kill it, QE is then important and res less so. Very large CCDs are expensive and the QE isnt that flash, id say for bight widefield, youd have to be pretty keen to go CCD. Less expensive small chip CCDs undersample with refractors, not a good match.

Originally Posted by strongmanmike

What's this?... a Lagoon Nebula with stars?? and kinda normal colours ....nearly didn't recognise it

Mike

Boring he , thats why I juiced it up a bit as a comparison rather than just a pic post. Im running out of different ways to image M8, ive done it too often .

Originally Posted by dugnsuz

Very nice comparison Fred - nebular detail and tight stars on the HaRGB image is marked in comparison with the RGB pic. Very heartening as this is an imaging path I'm embarking on!!
How did you find the processing? So far I've found simply using the Ha data as a Lum layer pretty easy - and I've achieved better results with this simple combination over the more complicated Ha/Red channel blend + Ha Lum channel blend.
What say you!!??
Thanks for this
Doug

Thanks Doug. Well, I found the Ha processing hard, but as I said previously, the Ha data wasnt good, it needs a lot more exposure time relative to RGB than a CCD, but then again they were only 5 min subs, and half the imaging time was taken with ICNR, im trying a seperate dark stack next on M16.

Not sure what you mean by Ha/red + Ha/Lum, ....altogether?. Red in the mono Ha (as Lum) would boost red saturation lost by useing just Ha as Lum, but would make colour balance tricky. Just boosting red in the RGB layers usually does the same thing. The red channel on its own then can look awefull, but RGB image quality in an Ha/lumRGB is less important than with straight RGB. Lum in Ha (as the Lum channel) can boost brightness and reduce nosie, but works best with a layer mask and some selective painting (on the mask) so detail is not lost on bright features. Marcs tweak is a good example, and Greg also does this to good effect.

As you say, this is more complicated. I found (so far) just Ha as lum with lots (I mean mega hrs) of data, and perhaps layer masks to selectively sharpen highlights and blur dim bits gives the sharpest detail, but it takes time (both in exposure time and in PS).