[naskies (Dave)]

Originally Posted by johnnyt123

Hi All..

My first stem into LRGB imaging has begun with the arrival of my new QSI 683wsg-8 which arrived last saturday.
it has LRGB Astronomik filters and Astrodon Ha, SII, OIII filters.

Hooray!

Now i have no experience in image acquisition or processing when it comes to LRGB so i am hoping all you those experts among you can give me a few tips.

I quickly imaged the Horse head 2 nights ago exposures were single subs as folows:
L: 8 min
R: 3 min
G: 3 min
B: 3 min
Ha: 5 min

Ha is only a narrow part of the full spectrum of R, so you'll need much longer subs to get a reasonable exposure. Many people use subs of 15 - 30 mins length - it depends upon your tracking, histogram, etc.

What i notices that in Ha the stars are very tight but in RGB they appear more wholesome or fat. are they blown out or is this blooming...???
How do i stop this happening?

It's happening for two reasons. First, your LRGB subs are pretty out of focus - this gives you bigger stars because the light is spread out across a larger area. Your Ha exposure has much better focus - the nebulosity is sharp, stars are nice and tight, and you can see diffraction spikes in the bright star Alnitak. (Note how the diffraction spikes are missing from your LRGB image.)

Did you re-focus between filter changes? Most filters will have slightly different focus positions, so if you used the Astrodon Ha filter to focus and then switched to Astronomik RGBs, they'll most likely all be out of focus. Some manufacturers claim that their filters are "parfocal", i.e. have the same focus distance, like Baader does with my LRGBHaOIIISII set - but when I actually measure them they differ by tiny amounts.

Second, as Andrew points out narrowband filters will suppress a lot of star light and therefore stars will naturally be smaller. In this case, it's mainly a focus issue.

Also i dont know how to incorporate Luminance into my images in Photoshop CS6 or Ha as luminance.

Here's a step-by-step guide:

http://starizona.com/acb/ccd/software/ps_lrgb.aspx

In fact, the entire Guide to CCD Imaging is well worth reading:

http://starizona.com/acb/ccd/ccd.aspx

What software for processing do you all recommend? is Pixinsight worth it?

Any further advise would be greatly appreciated.

Also Deep Sky stacker cant seem to stack my Narrow Band subs.
I can see countless stars but it for some reason can only see 10 or so and cant stack. Help please...

Please find attached the combined RGB (No luminance) and the Ha single shot 5 min exposure..

Thanks John

You probably have the threshold set too high - on the register images dialog, there's a second tab where you can set the threshold. In narrowband subs, the histogram is often bunched to the left (especially in your case with short Ha subs) so you'll need to drop the threshold way down to say 5%.