My guess is that the 'red' in the dust around the Iris is reflected general starlight, filtered down to reddish by all the dust itself. So I don't think it requires super deep-red sensitivity the way Ha does. What it requires is time, and the higher the background light pollution the greater the amount of time required.
There's also some processing decisions at play. When I was working on a widefield Iris image a ways back, a simple photometric color calibration + stretch in Siril showed a much more brown-reddish tint to the dust than the default StarTools coloring did.
NGC 7023 – Iris Nebula
Re: NGC 7023 – Iris Nebula
Thank you, Ron 
I had a look at your Iris Nebula image on AstroBin. What an amazing wide field view this is! I think, this is from your club site location, right? And what an astounding quality and high resolution you can get with such a small scope. The stars seem to have a nice, strong colored halo? Is this due to the characteristics of your scope or was it done with post processing, perhaps using the Super Structure module?
So you took nearly 9 hours of light at f/6 versus 6 hours at f/5 for me. Your cam may have a slightly better efficiency, but I think, both is not too far off? So in this case the main difference could be the darkness and transparency of the sky?
I will try to reprocess my image, as you and Stefan suggested. And I will try to get a few more hours of light. But I will have to wait a few weeks, because it doesn’t get dark here any more.
Best regards, Dietmar.
I had a look at your Iris Nebula image on AstroBin. What an amazing wide field view this is! I think, this is from your club site location, right? And what an astounding quality and high resolution you can get with such a small scope. The stars seem to have a nice, strong colored halo? Is this due to the characteristics of your scope or was it done with post processing, perhaps using the Super Structure module?So you took nearly 9 hours of light at f/6 versus 6 hours at f/5 for me. Your cam may have a slightly better efficiency, but I think, both is not too far off? So in this case the main difference could be the darkness and transparency of the sky?
I will try to reprocess my image, as you and Stefan suggested. And I will try to get a few more hours of light. But I will have to wait a few weeks, because it doesn’t get dark here any more.
Best regards, Dietmar.
Re: NGC 7023 – Iris Nebula
Thank you, Dietmar. Yes, my image was captured across 4 or so trips down to the club's B4 site. If your location has brighter skies that will only multiply the amount of time you need to get similar SNR for the dusty parts.
The large star halos I think are from the scope + ST's deconvolution. Siril left the larger stars just as bright blobs, while ST coalesces the bright cores. That scope is a doublet. It has decent correction, but still enough CA to notice in the brighter stars (my current 65mm triplet has much better color correction).
The large star halos I think are from the scope + ST's deconvolution. Siril left the larger stars just as bright blobs, while ST coalesces the bright cores. That scope is a doublet. It has decent correction, but still enough CA to notice in the brighter stars (my current 65mm triplet has much better color correction).