ollypenrice

The outer rings on the flats are pretty much the light spectrum, so I wonder what might create that. A diffraction grating consists of elongated parallel lines which will open up white light into a spectrum. Is there, perhaps, such an object replicated in your light path? The rim of a filter or coupled adapters, for instance. If your light source for the flats is close to the objective, might it illuminate the inside of the dewshield or the lens cell in a way that light from the sky does not? Might it illuminate something circular which then works as a diffraction grating? This is just spectulation but how about extending the dewshield fully and moving the light source further away? Olly

You can paint a self portrait by dipping your hand in mud and pressing it against the cave wall. No need for all this, then: lly

Yes, you do! I hadn't noticed them and will look into them - or crop a bit smaller. Thanks, Olly

Capture and pre-processing, Paul Kummer. My post processing. RASA 8, NEQ6, ASI2600MC. The little planetary, just 1.8 x 1.5 arcmins, was dscovered by William Herschel and was created by a roughly 2.5 solar mass star. The dark nebula is LDN674. This a crop from a wider field in Aquila. Wouldn't it be nice to see a time lapse of PNs popping into view and fading across this field... Olly

Agreed. Our priority in this rendition was the dust rather than the gas. Olly

I'm working with OSC data. I realize that I could extract a luminance layer and process that as you suggest, then process the OSC data as I would have processed an RGB layer, the objectives being rather different in processing L and RGB. However, when StarX appeared, I (and many others) extracted the stars by subtracting the starless from the starry as you suggest. I never found that this worked as well as the routine I follow now. I do like my present routine though it involves making some calls which vary from image to image and sometimes requires small stars to be processed differently from large ones. There is absolutely no need for this. The minimize filter, so far as I can see, belongs to the older processing techniques in which stars were not extracted. When they have been extracted, and the starless image has been given a very hard stretch without them, the extracted 'stars-only' can be replaced as a top layer. Using the grey point slider you can take them from entirely invisible, through tiny to small, medium and then large. What would I want to do with the minimize filter? The grey point slider gives me total control of star size. Olly

I have total control of star size when re-applying them using blend mode screen and, yes, I gave them a Gaussian blur but maybe not enough. Now increased. Run Star XT then here's the workflow in Ps. StarXterminator workflow in Photoshop. 1 Stretch standard image as usual to about 60 to 80% of final stretch. Simple stretch, nothing detailed. Save as Proc 1. 2 Run star Xterminator and save the starless image as Starless. 3 Continue to process Starless. Cosmetic repair of artifacts, harder stretch, contrast enhancement, noise reduction, sharpening, colour etc. Save. Select and copy. 4 Use Open Recent to re-open Proc 1 and paste Starless as a top layer. 5 Invert both layers. 6 Top layer active, change blend mode to divide. 7 Stamp down. (Alt Ctrl E) 8 Top layer active, Invert. 9 Flatten Image. (I seem to have to do this from the toolbar Layers dropdown because CtrlE doesn’t work.) 10 Save as Stars. 11 Select Copy 12 Paste onto Starless. 13 Blend mode to Screen. Actions 5 to 9 inclusive can be recorded as a single action. 14 The stars can be reduced simply by lowering the mid point in Levels. Small stars can look too hard and can benefit from the simple contrast tool to reduce contrast. Large stars with halo or bloat benefit from an increase in contrast. Other possibilities include Gaussian blur or a reduction in top layer opacity by a tiny amount. Stars which look ‘stuck on’ over nebulosity can be made to settle into the image by means of a dab with the burn tool on the bottom layer, just underneath them. Olly

OK, I've softened the stars a little - though I'll continue to experiment with ways of recombining them with a starless layer. Thanks for the critiques. Olly

Excellent images and the standard of judging has been transformed. To be honest, the Drechsler team just had to win this with their consistently ground-breaking work. Olly

They do, I know, and I've mitigated that effect to some extent by lifting the shadows around them. I used to use blend mode Lighten to re-apply stars but now greatly prefer Screen. There's a third way which I haven't yet tried. I do think that the re-application of stars is an area to work on but, overall, star removal takes us way deeper into the nebulosity and I'm happy with what I'm doing as a 'method in progress.' Olly

I actually gave them a Gaussian blur of 0.6 in Ps and applied the star layer at slightly less than full opacity to soften them. Perhaps I should gave given them more blur... Olly

Paul Kummer and I have extended our 2 panel Bat to 3 panels to include the dusty Barnard 150. This was a good suggestion of Gorann's, and SGL member George Sinanis kindly supplied nice OIII data to bring in Outers 4, the Squid. The spirit of this image involves featuring the dust so there is no Ha here, just OSC and George's OIII, without which the Squid is invisible. It's always pleasing to mention the name of the great and honorable Edward Emmerson Barnard, who was both the last of the great visual observers and the first of the great astrophotographers. Olly

I like the second one which has more colour range, the blues making themselves visible in the spiral arms. I do some things in PI to start with: DBE/ABE, SCNR green, BlurXterminator. For the rest, I'm glad to get the hell out of there and into the touchy-feely environment of Photoshop. Olly

I love this target and this is an enjoyable rendition. Regarding the stars, inevitably I'm going to say, 'somewhere between the two!' Sorry!!! For me the stars don't add an illusory sharpness, they mask a kind of mottling introduced by star removal. Olly

Both renditions are valid and attractive as well as being a testament to the portable equipment being used. Personally, I don't do much in Pixinsight and prefer the Photoshop environment by a mile. Olly

AstroArt has a feature called 'remove line' in the Cosmetic toolbox. You put a point at the end of each line and it disappears with a click. I wouldn't use it to remove all diff spikes but those which seem disembodied (from out of shot stars) or over-extended could probably be removed. Other software may have something similar. Right, that's it! Feather dusters at 400 yards!! lly

It's nice that you should make this point because I felt the same. It was one of the little nuances that made it enjoyable to process. Olly

My co-conspirator Paul Kummer described this as a 'B list image' or even a''C list.' I don't see this rendition sending it to the top of the target hit parade either. But... it's there and it looks like this. Trust me, there isn't much to work with, but 85x3 minutes in the RASA 8 gives data which can be stretched to screaming point. This job had more to do with torture than with processing. Capture and pre-processing by Paul, post-processing by me. Olly

BTW, the 'Crescent' name makes sense if you observe this visually. Only the bright outer rim is visible and it does make a crescent shape. Olly

Good! Olly

This is very classy imaging indeed. Sharp, clean, balanced, free from exaggeration and with totally invisible processing. Chapeau! Olly

Nice. Is that the full field at 250mm FL on the 2600 chip? It seems much more restricted than I'd have expected. Olly

The Squid is outstanding, bold and smooth. In your shoes I would go for more broadband rather than more OIII. Paul Kummer and I recently did an image of this region in one shot colour with a very fast system. The result is almost the opposite of yours: we have deep dust and reflection nebulosity but no Squid whatever! We should collaborate! Olly

Very good! Simple as that. Olly

Lovely, and an inspiration for all who work from light polluted sites. Olly