Yeah, never waste your time doing OIII on galaxy shots. Even Ha can have little effect unless there's a lot of HII emission going on. Even then, only apply Ha to the galaxy (limiting to the emission elements if you can) and not to the whole frame, so your stars retain RGB colour.
Also think about doing a bit of deconvolution to reduce star bloat and add detail. Careful though, it's easy to overdo decon.
Yeah, never waste your time doing OIII on galaxy shots. Even Ha can have little effect unless there's a lot of HII emission going on. Even then, only apply Ha to the galaxy (limiting to the emission elements if you can) and not to the whole frame, so your stars retain RGB colour.
Also think about doing a bit of deconvolution to reduce star bloat and add detail. Careful though, it's easy to overdo decon.
Thanks Marcus, just the sort of info I need, will do as you suggest.
Quote:
Originally Posted by gregbradley
Nice image but the red halos around the stars is a problem. Did that come from the combining the Ha with the RGB?
As Marcus pointed out the Ha is going to damage the stars with little gain. There is a little bit of Ha in 2997 but not a lot.
Overall an excellent image that you can build future images on.
Greg.
Thankyou Greg.
It looks like the Ha did stuff up the stars. Will have to start the processing all over again.
I can't beleive just how much time it takes, not to mention keeping track of what's what...
Not a bad galaxy shot that Peter It's a great spiral too.
It can be worthwhile hitting OIII on a few of the closest galaxies, obviously LMC/SMC but also Barnards galaxy and NGC 300 and M101 also come to mind but generally you will get nothing much to nil, especially beyond our local group. Ha on the other hand, well it can be collected quite successfully from lots of galaxies and used to enhance the HII regions, out to perhaps around 60 Million light years or so..? After that the Ha line gets red shifted out of most narrowband filters anyway so using them will do nothing.
Not a bad galaxy shot that Peter It's a great spiral too.
It can be worthwhile hitting OIII on a few of the closest galaxies, obviously LMC/SMC but also Barnards galaxy and NGC 300 and M101 also come to mind but generally you will get nothing much to nil, especially beyond our local group. Ha on the other hand, well it can be collected quite successfully from lots of galaxies and used to enhance the HII regions, out to perhaps around 60 Million light years or so..? After that the Ha line gets red shifted out of most narrowband filters anyway so using them will do nothing.
LHaRGB combo's are worth trying on many galaxies
Mike
Most interesting info Mike.
I had a crack at NGC300 and your right, there were many nebulas? rich in OIII.
As an aside, yesterday NGC2997 was image of the day at Astrobin.
It made my attempt look very pale indeed.
However to be fare, this chap was using a RDK700 (scope the size of a small car).
It's a great spiral too.
