Fegato

Ha ha - yes, the weather has been so bad - nice to have a go at processing something! My effort below... Observations: 1. The integrated image was noisier than I'm used to dealing with, so I think as has already been said, the best improvement can be made with more data. I purely applied NoiseX with this, after initial stretches, and quite strongly. I think blotchiness is not really there, but I guess it's a bit "plastic" from the noise reduction 2. I got tiling artifacts with StarX, so had to apply the "Large Overlap" option to prevent this 3. I've probably not stretched as much as yours. This felt like a bit of a limit to me. I had to deal with some nice purple and green hues in the background dust, and used a range mask to push the saturation a little in the nebula and dampen it elsewhere Having said all that, processing this reminded me that I did find my own effort on the Cave a tricky one to process - I think maybe it's an area with quite a lot of obscuring dust that makes it difficult to pull out detail? Edit: looking at that, I've perhaps not got enough contrast - a bit too dusty?

OK yes, maybe just more data will have the most impact. With regard to the green cast, I thought it was BackgroundNeutralization that really got rid of that, rather than DBE? Mind you, I find I still have issues with background colour after further processing, although I'm often stretching hard to pull dust out, which puts everything a bit on the edge. NoiseX - I was sure it was recommended as best on non-linear, but I can't find any advice on this on the RCAstro site now, so can't really back that up. an endless road of discovery and re-discovery this hobby...!

I would guess 3 hours at F/7.5 (if that's right?) is a little bit on the low side, so more data would probably help In terms of workflow, there are obviously different options which work for different people, but a couple of comments: I always apply DBE as a first step, which is what is normally recommended. I've learnt to do this starless now (courtesy of a free Adam Block youtube video), which makes it so much easier on a busy frame like this. So run StarXTerminator with Unscreened option not ticked. Peform DBE on the starless image, making sure to tick the normalize option - much easier to place samples on the bits that have minimal dust or nebulosity. Then add the stars back with PixelMath - a simple $T + stars. Did you run NoiseXTerminator before stretching? I thought the recommendation was on a non-linear image (but not after too much processing). I tend to do it after an initial couple of stretches, but before any other processing.

I don't have any experience with fast refractors, just the Hyperstar and now RASA. But once you get down to F/3, your CFZ is obviously very tight, just handfuls of microns. So it might not be a problem with the reducer per se - could just be that your backfocus distance is a tiny bit out (plus any minor tilt). The shape of those stars might be some sort of optical issue, but they are all pointing in to the centre, so you might just need a tiny bit more distance to the sensor? My experience at F/2 has been that I need a precise tilt / backspace tool (in my case, Octopi) as part of the image train in order to do the various tiny adjustments necessary to get a nice flat field. The flat field is there to be had, but requires patience and the right tool to find it. If there's a tilter on the camera you could try tiny adjustments with that perhaps? (although those tend to be a bit rough and ready)

I suppose I've not been imaging seriously for that long - just over 4 years, but this is certainly the worst spell of weather here I can remember (with the focus on clear nights, although possibly anyway). Horrible since the end of June, and I've got used to July to September being pretty productive, so quite depressing really. I planned a 2 panel mosaic of LBN437 (the Gecko) and parts of Sh2-126, and wanted to capture a good wide field around it including the trail of dust away to the corner that you see in this image. I managed 56 minutes on this panel in reasonable conditions on 25 August. However, the second panel attempt in early September was plagued with hazy cloud and various issues, meaning that mosaic really doesn't work, and those subs need binning (meaning dustbin rather than the other sort of binning 🙂). No further moonless opportunities have arisen. My forecast here into November looks atrocious, so I fear this target is going to disappear for another year. So here it is - half a Gecko...

I think you're always likely to have some - I guess optimum will depend on your set up - optics, sensor size etc. Mine needs a little work at the moment - just checked a recent sub and it's 19%. Can definitely get a bit better than that. Key thing though is what the stars look like. If I get them round in each corner, I try to stop looking at the numbers!

Here's the curvature plot from CCDI and also the aberration inspector from ASTAP. Both look pretty good - numbers in top corners just slightly bigger than bottom. I think the mid points in the lines give you an idea on your backspacing, but can't remember which way round the numbers work for too close / too far. It'll be in the documentation somewhere I guess. But again, it's pretty close. I use the Hocus Focus Aberration inspector in NINA for my tilt management and so on. It uses a whole focus run to compare curves for all corners, so takes a little while, but you get a good clear picture. I think the ASTAP documentation recommends this method of using our of focus stars either side of focus to build up a picture. Looking at the stars, it does look like some slight adjustments might help, but you'd need a precision tilter probably?

I like that - not seen a Pacman with surrounding dust before. You encourage me to have a go at it in broadband, I'd sort of written it off as an interesting target for my RASA. I'm not so bothered about the colour - I like the way it blends in to the surrounding dust. In Pixinsight I might have tried a Range Mask to just highlight the bright parts of the image (i.e. just the Pacman area) and boost the saturation there a bit. But you don't want to spoil that blending with the dust. I guess it's not particularly sharp... you could try some sharpening, but I must admit I rarely try this as I'm never really happy with the results. And after all, it is "nebulosity"! Maybe it might benefit from some more data, depending on the speed of your system, but 3 hours is a fair bit for broadband?

I have the 294MC and it's a good camera, but as above, it's not consistent at very short exposures and therefore flats need to be calibrated with flat darks (rather than bias) which can be a bit of a pain. It also has amp glow and definitely requires darks as a result. The 533 has a slightly more modern sensor and like the other newer ZWOs - no amp glow, and generally better performance (lower read noise etc.). Having said that - you can take brilliant images with the 294 and awful ones with the 533 of course, so I wouldn't argue against a 294 if the sensor size suits you better.

Nice! West Wales has been the same weatherwise. Scope was out for 5 nights this weekend with a promise of multiple clear nights. All I managed was to polar align, and then the cover stayed on the whole time. Depressing…

Adding any glass into the light path will increase the required backfocus distance by an amount equal to ⅓ of the glass thickness. So e.g. if your optimum distance is 55mm, adding a 3mm filter into the light path will increase this to 55.1 mm. This is obviously a small amount, and whether there's any real impact will depend on your set up. With my RASA at F/2.2 even swapping a 3mm filter for a 2mm one has a noticeable affect on my corner stars (after re-focusing). As a result I use a clear glass filter when shooting broadband, and this has same glass thickness as my dual narrowband filter.

If the trailing is due to optical issues (tilt, backspace etc.), then shorter exposures won't help. I should have added that my shorter exposures were taken after I'd sorted out the tilt / backspace issue, and they could be short because I was only interested in the stars. If anything, I find shorter exposures with my RASA actually accentuate these sort of issues, as longer exposures can cause a bit of bloating! With regard to the L-eNhance - what are you using when you're not using it? Just wondering if the addition of the filter is changing your backfocus distance (e.g. if you had no filter at all when not using it), which could be why things are worse with it.

Wow, that's a lot of kit going at once - good luck! I will probably just stick to one rig - I have to wheel out and polar align / calibrate each time, as no observatory (although if there's a spell of clear nights I'll leave it out under cover), and I'm not overly motivated to get another one going. My solution to getting the most out of limited clear sky time is using a RASA11. I sometimes think about getting a very wide field rig with a 135mm lens and a small tracker mount, but haven't even started window shopping for that. I'm still mastering what I've got, I guess. The other thing I occasionally mull over is having a remote set up in one of the Spanish sites, maybe FL around 1200mm for smaller FOV at a higher focal ratio - but that is a lot of commitment in time and money.

Yes I suffered with this recently and it's a right pain. Not much use to you I think, but I use Pixinsight, and I found that BlurXTerminator did help a bit with the star shapes. However, in the end, I just reshot the stars quickly. This involved 10s exposures with no guiding or dithering, and only 40-50 exposures, so I didn't waste much extra time (albeit I had to wait a full month to get another clear night!). Took the stars out of the original images and patched the new ones back in.

I've got some clear nights forecast here too - I'm trying not to get too excited...

Thanks @CloudMagnet and @Mr Spock for your comments. I've been back through my processing, which has reminded me of the fact that you really shouldn't apply processes without understanding or thinking exactly what you're doing! I use Pixinsight, and it is very rich in capabilities and as a result quite complicated. I like this, but sometimes need to take more care! 1. I was applying Background Neutralisation in a sub-optimal way, failing to use a proper background sample. I'd always done this properly until I started using Photometric and and now Spectrophotometric Colour Calibration processes. In redoing this, I found I'd actually neutralised a fair bit of faint nebula, as well as failing to get a good neutralised background. 2. Some of my stretches seemed to be affecting the background. The Script EZ Soft Stretch was a particular problem, and as this is no longer properly supported, I think I'll stop using it. 3. I still seemed to pick up some loss of a neutral background through stretching. Background Neutralisation is supposed to be run on the linear image, but I tried applying it on the non-linear image and this has done the trick. It also altered the colours across the image, but as they are sort of made up anyway... Any expertise anyone can offer on maintaining a neutral background during Pixinisight post-processing would be welcome! Here's the end result anyway. Not as pink, but a lot more faint nebulosity across the image.

No that's fine - I'll have a more considered look. I guess my PixelMath attack on the red has probably done more than I wanted it to!

I've had another look this morning, and I'd obviously undone my SCNR at some point and not re-instated, so definitely some green. This might be a bit better?...

Thanks! I did SCNR some green out fairly late in the processing, but it was fairly light touch, so maybe not enough - I'll take another look when I can get some better light conditions tomorrow.

Well, the weather here in South West Wales since the end of June has been appalling, and after a pretty good first 6 months of the year, I've struggled to get much imaging done. I normally just focus on broadband and moonless nights, but with a couple of vaguely clear moon-filled nights in September, I got the NBZ filter out and had a go with that. I'm not so keen on very red Ha filled images, so the Sadr region was a bit of a challenge to process. In the end I decided to add some Hb to my Ha dominated image... or at least, I did some sort of unscientific / random "Hb" addition. This pinkish image has 15% of Red (above Median value) added to the Blue channel. If not scientific, it was relatively easy to achieve. RASA 11 on CEM120, ASI2400MC Pro. 7 hours of 120s exposures across 2 panels with IDAS NBZ filter. 100 x 10s across 2 panels for RGB stars.

Strange to call that a quad filter, as that bandpass is more like a LP filter than quad narrowband. It doesn’t seem that different to the L-Pro. Do you know how they are marketing it?

I had hope of 2-3 hours clear, wheeled it all out, and my only success was to polar align, which took ages. Clouds had come in, and I was too tired to wait any longer. Woke up in the early hours to a very bright moon shining through the window (a time when the forecast said any clear spells would be long gone). I await Saturday's forecast clear night with low expectations...

I'm half way through my version of this. Really struggled this summer with poor weather, and West Wales has not benefited from the recent few clear nights, so it remains unfinished although I started weeks ago... fingers crossed for October. Anyway, it's hard to get much definition to the Ha without using a filter. And you really need a filterless version to get the best of the dust. So a combined Ha & RGB gets the most out of this target I think. I use OSC and am using a dual narrowband to get the Ha. I don't think there's much OIII to be had here, so I'm not sure there really are any blue bits to speak of?

Just a tip on using DBE in PI... I use StarXTerminator, and if you remove the stars prior to DBE (with unscreened option not ticked) it becomes so much easier. You can clearly see what's gradient and what's dust with no stars, particularly in a rich star field like this. Perform DBE with the normalize option ticked, and then add the stars back (simple $T+stars). I now do this on every image, and it's improved my results no end. I've realised some previous images had swathes of dust and nebulosity destroyed by poor sample positions in DBE.

I can't really give any tips, as I've never really happy with sharpening on DSOs. I've used UnsharpMask on the moon and planets, but rarely on a DSO image. I guess I'm mostly shooting fairly wide field, and prefer the "nebulous" look to risking production of artifacts and yo-yo-ing between sharpening and noise reduction. I do sometimes see an image that looks sharp and good with it, and think wow - wonder how they did that!