IC 1396 LLRGB

[Mike Hawtin]

Bit of a tight squeeze for a single panel with this set up but there was no time to go for a two panel mosaic.  Taken through the Borg 71FL with a QHY9M, still too much blue bloating even with the Idas LP2 filter, I would be grateful for any tips to address this problem,  I've run it through Noels actions halo reduction but could see no real difference.  Anyway here it is for now blue blobs and all, I hope you like it, more info on Astrobin.

Mike.

[ollypenrice]

The blues are bad news, as you say. Are you dead sure about focus? If that's the Borg in focus then I think it has a problem. It would be good if this were the cause, for sure.

I suspect Noel doesn't get to it because the blue is not so much a halo as a generally too-big-star, so to speak.

All I can think of would be to process the blue channel separately from the linear stage. You could try a curve which flattened earlier than for the other channels, keeping the stars down.

The blues are also very cyan, so using Selective Colour to drop the cyans in both cyan and blue might help.

And finally you could split the blue channel and run Noel's 'make stars smaller' on it before recombining.

Olly

[Mike Hawtin]

Thanks for the feedback Olly.  I am sure about focus, I use a Bhatinov mask and the Bhatinov frame grabber application, reds and greens are nice and sharp, the blues have pronounced halos and as is to be expected blue stars in the luminance frames are also bloated.  The IDAS filter has helped to a degree, bringing the blue star sizes down by about 40% but still significantly larger than the other colour channels.  I know I have more work to do with regard to collimation and this might tighten things up a little.  I've tried star reduction in PI with Morphological Transformation but this also reduces star brightness which I think skews colour calibration.  Running "make stars smaller" is a good shout, I'll give that a go and see how I get on.

Thanks again for the suggestions.

Mike

[Mike Hawtin]

Back again Olly, I've done a sequence of blue frames to check focusing and found the Bhatinov method to be spot on, the bloating is down to the scope itself or the reducer/flattener.  I have reprocessed the original data this time using lighter bludgeons and it seems much better this time around, even "reduce blue halos" has worked for me.  I have added another link to the image as deleting the original on Astrobin has removed the whole page, perhaps if the mods notice this they will be kind enough to move the link back to my first post.

Mike