ollypenrice

I really do like this image, particularly in the way that it shows the increasing presence of OIII towards the centre of the nebula. You've done a great job here. Olly

Great stuff. Wonderful PN! Olly

Clearly the M45 needs colour balancing since it's green-dominated at the moment but you seem to have red stars in the right places. (There aren't many in M45 because it's a young cluster) So it looks fine to me. Olly

Rather than posting a link to a TIFF, just post a stretched JPEG. Many members are reluctant to open unknown files and some, like me, have slow internet connections. You'll get a much better response that way. Olly

The dust is good but there are intensely colourful bits in this region which aren't yet strutting there stuff, to my eye. Olly

That's a lovely clean and deep L layer but this is surely a colour object. Go for it! Olly

Cover the finderscope's objective securely as well. Do not, ever, rely on eyepiece-only solar filters. The objective of the scope must be filtered. Olly

In Ps, Noel's Actions 'Local Contrast Enhancement' will do a similar job, or you can do a masked stretch through an equalized mask. It's all down to increasing contrasts on a scale considerably larger than sharpening, though the principle is similar. Olly

Well, we're in the land of the guess now and I think you're 'in the zone' with the colour but, perhaps, towards the blue end of the zone? My estimate of OIII might nudge it to towards the green a touch but that's just me. You have strong signal for this strange object and, if the image were mine, I'd be more concerned to pull out more structure, if possible. In some of the deepest renditions we see something like a loosely wound coil spring along its length. An extended helix, if you like. I wonder if this might be latent in your data? I would explore this direction in Photoshop rather than PI. But what happens if you run LHE? I'm sure it would damage the global image but if just applied to the Squid? Olly

I agree wth Vlaiv. It's very much on the green-blue border. When I look through my own OIII CCD filter at the daylight sky the angle of the filter makes a dramatic difference so that I see blue sometimes and green sometimes, but certainly never anything like cyan. In a nutshell this is where the spectrum puts it. What I do with objects in which the OIII is visible in the RGB layer is keep the RGB on the screen for reference. I then add OIII to HaLRGB green channel in one version and add it to HaLRGB blue channel in a second version. When I put these into Ps layers I can balance the green-blue contribution of the OIII with the RGB as my reference just by moving the opacity sliders. In the case of the Squid, the darned thing is only visible in OIII so I just made it greenish blue or blueish green. There are lots of greens in planetary nebulae, many of which are stronger in OIII than Ha. Thor's Helmet, for instance (if you consider it a planetary since Wolf-Rayets are a special case, perhaps.) When I was a relative beginner, and before SCNR green and Hasta La Vista Green appeared on the scene, I posted the notion that green was the root of all evil in AP colour. The idea didn't seem to strike any chords at the time but I think I do now feel vindicated... 😄 There used to be a green grinning emoticon but that one will have to do!!! Olly

Wonderful image with particularly subtle dust clouds. I do love this region. Olly

Lovely job, Rodd. Super. Olly

The improvement is considerable over an image which was already excellent. Olly

It is but, to do that, information from more than one pixel must be compressed onto one. It's routine to find that, if you don't have enough data to present an image at full size (meaning one camera pixel getting one screen pixel), you may still find it looks good at 66% or so. In fact you really do need a deep dataset to show at full size and sometimes you might make a decision not to try but to accept a smaller size. I think folks will often do this when making a mosaic, for instance, because the final image is going to end up huge in any case. The net effect of resampling downwards is similar to binning. Olly

Does your stacking software offer this option? Some do. Failing that, just resizing in Ps to the size you feel the data will support will have a similar effect though Vlaiv advises binning for the best SN ratio. The big mosaic captured by Yves recently, and which I post processed, had been resampled downwards at the stacking stage in APP. It was incredibly clean. Because I can hardware bin I haven't done this myself. Olly

Rather than putting your stars back in blend mode Screen you could try blend mode Lighten. That's working for me. Olly

I'm impressed!!! 👏 Olly

Over sampling with modern CMOS cameras is not the issue it was with CCD. You won't resolve down to your numerical sampling rate but you should still get a good result. Just software bin the captures. Olly Crossed with Merlin. 😁

Oh, too much! I worship shellfish... I still have three bottles of Champagne from Per's gift of a case as well... Kind of hard to drink it, though. Olly

In my view there's nothing wrong with comparing F ratios and exposure times in this way if the focal length is constant, the variable is aperture and the pixels also remain the same size. Olly

Yes, no question. That's a stunning setup. I'm quite prepared to accept that the OSC rule book has been re-written by modern cameras and have said so already. The dual band filter has also done a brilliant job. The old technology can't get near this in the time. Also very importantly, you have nice tight, shapely stars throughout. The RASA strikes me as being in a different class to the Hyperstar. Olly

There's a thought. I wonder if Andrew considers shirt wrinkles as a form of noise? Even worse in the case of sheets when you're trying to get to sleep. Olly

No, it was with the Moravian and its 8300 chip. The clipping by the dark was enough to bite into the faint data. Applying our existing darks simply trashed the stack. Even using the 10 minute dark on the 15 minute subs produced the same effect. In the end I just used a master bias but I'll need to shoot new darks. However, the RGB from the following night stacked normally. I've checked the data in the FITS headers and found nothing abnormal (temperature being the one I suspected.) All was as usual... I'll try stacking in a different instance of AstroArt on another PC. Olly

The ZWO ASI120MC you mention has 3.74 micron pixels so it actually has a considerably higher resolution than, say, a 450D with 5.2 micron pixels. Resolution derives only from pixel size and focal length. What the DSLRs have is a much bigger chip and so a wider field of view. Olly

Thanks Dave. What baffles me is why it only happened to one dataset and has been running normally with the same darks till yesterday. It's not called a dark art for nothing! Olly