ollypenrice

These are both Ha-dominated objects. How much Ha signal do you pick up? Have you tried some Ha targets already? Olly

We do get rather hard-edged but circular disk-like halos on some stars but what you have are highly asymmetrical flares and those we don't get. To my mind, BTW, StarXterminator is a game-changer for the RASA, which goes gloriously deep but gives indifferent stars. (Certainly not refractor standard.) However, my present method, still under experimentation, is to give the original image a partial stretch, save it, de-star it and give the de-starred image a little more stretching and cosmetic fixing of artifacts around where the larger stars were. I then put the still starry version as a layer on top in blend mode screen or blend mode lighten, combine them and go for the final stretch. In a nutshell the stars get a lower stretch than the rest and can be made to look pretty decent. Without StarX I'd be considerably less enthusiastic about the RASA. With it, I'm a happy bunny. Olly

We don't have any bright stars in images since we changed to a U-shaped cable guide but we''ll try to shoot some for you next time out. I really don't think we'll see anything like yours, though. Our previous O shaped cable guide gave elongated halos on M45 but we had no flares at all. Olly

No astrophotographer needs any new challenges, ever! Olly

I think the simplest calculation may be to find the area of clear aperture which, in the case of the RASA 8, is 27,572 square mm. It's a shame about your stars. So far we haven't seen this with the one I'm involved with. I think Celestron just need to fix it for you. Olly

No! There are a few monster one-off scopes in this region and what they all have in common is that they never work! 🤣lly

Peter Drew gave us the Todmorden Pier and here you give us Athenian pier. I can see this bringing much domestic harmony... Olly

If your PA is out you'll get field rotation around the guide star, however well the guide star is held in place by the guider. In a nutshell, the guider can only do so much. Olly

The trick is to grow old, retire into a permanent holiday under good skies and pour a lot of non-portable concrete! 😁lly

This rings alarm bells for me straight away: 'I focused and PA well via the ASI.' Does this mean you believe in your PA because some software tells you its good? I've had plenty of experience of software not being accurate in this regard. Once aligned I would do a simple drift test like this: point the scope towards the celestial equator in the south. Set up a 3 minute sub and, during this exposure, track at the slowest possible speed for 1.5 minutes one way in RA and then 1.5 minutes back again. This will produce an outward star trail and a return trail. If the PA is good the star trails will overlap, producing one single line. If PA is out you'll get a shallow angled vee. This test is software-free and direct so it can be believed in implicitly. Being suspicious of all things software I also prefer to guide by the simplest means possible and that's by the old fashioned ST4 cable. This means no 3rd party software, just the camera, the mount and PHD involved. Olly

That's a thriller! The background is a big part of its success. Olly

Lots of delicate interest in this one. Olly

Really well done on the dynamic range, Rodd. This one has an ultra-bright core which takes some controlling. Olly

I rather think you've put the Ring nebula to bed with this one, Peter! It has everything. Olly

I don't do false colour imaging but colour weighting is what it is in any scenario. Firstly I'd follow Vlaiv's suggestions out of pure common sense. When you want to reduce the impact of the Ha you have two simple options, bringing in the black point and adjusting the stretch. You can do both in Levels. I'd begin by looking at the colour balance in the background sky. If you want a neutral dark grey you need parity between channels. I'd probably use black point adjustment to get there. Next you want to balance the colours above the background sky level, so I'd use Curves. You could pin and fix the background at a chosen level then lower the Ha curve above that. In a civilized program like Ps you can do that while looking at the three-channel image in real time as you adjust the stretch in one channel only. But.. if you colour map as per Hubble and shoot an Ha-dominated image it's going to come out very green, surely? Why not try HOO instead? Or... do a nicely colour balanced image in which the Ha is greatly under-used and save that as a colour layer. Then use the Ha as luminance to restore the Ha interesting parts. Olly

Thanks. I didn't use the Tak lum on the RASA data, I combined the Tak LRGB with the OSC. I think what troubles me is not having a clear idea about what I'm trying to do with this one. The Ha seems to be too much or too little whatever I do with it. In this mild application there are nice Ha structures which hardly show, but rendering them visible overwhelms the rest. Olly

This is an oddball image with a tonne of data. I don't know what I think of it. It combines a full LRGB run from my old Tak FSQ with a full OSC run from Paul Kummer's RASA 8. Then there's 15 hours of Ha from the Tak. There isn't a lot of Ha signal but there is some so, in this processing, I kept it fairly quiet. In a previous image I pushed it harder. And, finally, the Cocoon itself is enhanced by two high resolution images, one from my TEC 140 and one from Yves Van den Broek's ODK14. At least noise wasn't a problem! 😁 Olly

This image came from two hours and fifteen minutes of exposure. (I'm not making this up!) Capture, as usual, by Paul Kummer, remotely driving his RASA 8 based at my place. ASI 2600MC, Avalon Linear. 45x3 min. subs. No flats (they over-corrected for me), ABE and SCNR green in Pixisight, the rest in Photoshop including Star Exterminator. My processing here. For aesthetic purposes this is a significant crop. Lynd's Dark Nebula 673 is in Aquila at about 600 LY. Olly

I love the first two but would never use Ha as lum. It turns everything pink and produces bright blue stars, often with halos. I'd try adding the Ha to red in blend mode lighten or blend mode screen, myself. Have you tried StarXterminator? I think it would be excellent on ths type of image. You de-star a partial stretch, stretch it harder, then replace the less stretched stars in Lighten or Screen mode again. This has transformed our RASA imaging. Olly

You can't please 'em all! I prefer the denser colour of the dust in version 2. In both cases I'd be wanting to play with the colour balance in the green-magenta axis, and the saturation, for the Iris itself. As Jody suggests, a highlight reduction would probably be good and would also intensify the colour round the Iris. I'd then bring up the higher greens, slightly, to pull the blues away from magenta. However, there are some subtle pinks in the Iris which are worth looking for and nurturing. Whatever, it's a fine Iris. Olly

You're too modest! These are great. Personally I'd do what I always do and paste one on top of the other in Ps and adjust their relative weighting till I found a compromise. I don't recommend this as an astrophotographic technique but as a cure for an inability to make decisions - which in my case is an acute malady! Super image. Olly

This is great imaging. Olly

That looks good. I've started doing my own prints with an Epson 15000 ink tank printer. The fact that it uses ink bottles rather than cartridges makes it much, much cheaper to run. I've found that I can quite easily beat the standard I was getting from commercial printers because astrophotos are quite unlike the pictures they are used to receiving. When I do my own, I make a small test print, adjust the image and try again before doing a big one (up to extended A3.) Olly

It couldn't be a tiny mobile bug? I once had this. I could actually see it move from flat to flat but, bizarrely, I was never able to find it physically. Then again, I think most of us have had problem flats for which we never found a solution. Do 'em again! This game is not as logical as some would have us believe... Olly

There's a lot to be said for the skies in France! lly