geoflewis

No blame David, it's just further illuminated an area of AP that I don't understand. It may be peeling an onion, but if Vlaiv or someone can help peel some of the layers for me, that would be good - though it might just make me cry of course.....

Hi everyone, I'm continuing to enjoy this discussion with the addition of @DaveS image and binning experiment, but it's taken me in to territory that I really don't understand, so I'm hoping that someone can clarify for me. The bottom line is that I don't fully understand the terminology, nor the real effects on an image of some of the operations being discussed. What do terms like downsample, upscale, binning actually mean in terms of image quality, resolution, or whatever is the correct term? I think I understand what hardware binning means, as that actually combines a grid of pixels (2x2, 3x3, 4x4, etc) on the sensor into an effective single pixel before downloading the data. Software binning is similar (?), but works differently (I think), but what about downsample, upscale, etc. Are these terms (especially downsample and binning) interchangeable, if not then what is the difference? If I bin 2x2 in sftware, then upscale x2, do I end up in 'exactly' the same place? What if I resize/upscale x2 then bin 2x2, is this also the same, i.e. what is actually happening with the image data as these operations are applied? Are resize x2 and upscale x2 even the same? What is downsampling? is it the opposite of upscaling? Sorry if I'm showing my ignorance too much, but I see these terms bandied about all over the place, but I can't find an authorative reference to distinguish between some of them. Anyone fancy taking a punt at this for me please? Rodd, sorry for hijacking your thread, but it was following the discussion that started with your superb M13 that got me here.

Well you got pretty darned close IMHO

Whatever Hubble-ize means, the result is suberb 🙂

Yes, the image gets better and better Rodd. I think your opening comment about colour is completely correct and on point, one must be VERY careful, something that I'm now coming to terms with. Personally I think you have achieved your goal of producing an image that looks like what I see at the eyepiece; of the very many images I've seen of this object, yours really does get very close to the eyepiece experience of my C14, so well done with that .

Ok so 5 minutes is a bit different to 20s 😏, even with the TOA 130. I agree the latest image is the best of the ones you posted, with much tighter stars, but I did like seeing more colour in the core stars of the 20s RGB versions, of which the 2nd, 'more relaxed' version was my preference. This is a target that I'll spend a long time with visually most years, by long time I mean 30-45 mins sessions just drinking in the view, trying to tease out more stars. I find my TV 12mm gives me the best views, but I now have a binoviewer with a pair of 19mm panoptics, so I'm looking forward to trying those on it. I don't think I've ever seen much in the way of colour at the eyepiece and I find that it is extremely difficult, nigh impossible to resolve stars at the core, though maybe every so often, one or two resolve for a second or two. I think my version is too colourful and recall that I messed with colour star masks and saturation to give them more 'pop', but am now fairly sure that I should have done less, or left them alone completely. Like I said, I've found this thread very interesting and informative, so thanks for that. Cheers,

Rodd, I've been following this thread and your several version of this image on Astrobin with great interest. They are all superb images of one of my favourite visual and photographic targets. Your earlier discussions with Vlaiv got me reviewing my most recent image of M13 (https://www.astrobin.com/full/347656/F/), taken with my C14 plus Optec Telecompressor (at ~F7), which I discovered was taken a few years ago in 2018, so maybe I need to try it again. It got me looking at how well that triplet of gold stars, that Vlaiv discussed, were resolved in my image, which comprised all 120s subs. What I really noticed was how little colour was in the core stars (particularly the blue ones) of my image compared with you original RGB images posted at the start of this thread. My image is much more like your lastest one which included data off the TOA 130. There are clearly more stars revealed in the outer regions of the cluster in your latest combo image, but the core is much brighter, with less colourful and well defined stars, so I was wondering what were the sub exposure lengths with the TOA? Whatever, it is still a cracking image and I hasten to add that it's in a completely different league to mine.

Probably true from here on in, but this latest version was definitely worth the extra processing. Very nicely done David.

Hi Dave, to my eyes you made quite a difference. The background is smoother, the galaxy tails are more prominent and the slight channel misalignment previously seen in some of the stars is corrected. Very nicely done

David, it is a really fine image. Stars are nice and round and it's pretty deep with the galaxy tails showing well, together with lots of other faint fuzzies to be seen, in addition to the Hickson 56 group.

I have a very understanding wife. It was something of a retirement present, along with the observatory, the C14 and the QSI camera. We became mortgage free when we moved from Surrey to Norfolk, so some of the released equity and retirement lump sum went on my hobby.....🙂

I paid £6.5k for my preowned mount 5 years ago. I am least the 4th owner....!! I won't be letting go of it anytime soon if I can help it.....

Hi Tristan, I layered B and D together with B at 100% lighten blend mode on top of D knocked back just a tad to 97% Normal mode. I also applied a gradient removal as I think there was one running broadly left to right. What do you think of this version?

The AP1200 mount is a monster. It's a 2007 model which hasn't been upgraded and I'm not even running any PEC. It barely knows that it has a C14 + 4" APO riding on it. I'm guiding through the OAG of my QSI583 and typically get ~0.5" total RMS, though some nights sub 0.4". Imaging scale is 0.43", so I'm around 1px.

Thanks Tristan, I know what you mean and I did wonder about doing that, or something similar, so maybe I'll give that a try. This is a C14 with native FL of 3910mm (F11), with an approximately x0.63 Optec telecompressor, so allowing for the moving mirror, then net FL will be ~2500mm.

After weeks of crap weather or clear skies only when the Moon was up, I finally managed to finish my first image since January. It is an LHaRGB image of the intermediate spiral galaxy M106 in Canes Venatici. I started the project in March in the run up to 1st Qtr Moon, but the ~8 hours of LRGB data that I captured proved unusable, so I shot all that again over the past week, or so. The Ha data captured in March seemed to survive ok despite the bright Moon, so I've used that. Total integration is just over 15.5 hours, comprising L=31x10m, Ha=19x15m, R=24x5m, G+B=22x5m each. Processing was all done in ImagesPlus, with Registar used to accuratrely align the 5 stacked channel images, before building the final colour image which also done in ImagesPlus. This was a very tricky image to process, with countless iterations at various stages of the process for both the luminance and colour images, before combining them, with 4 completed versions of which the above is V4. I really struggled to reveal the galaxy's outer halo whilst trying to control the noise in the background sky. I had both more crunchy and much softer versions, but have settled on this one - at least for now. I think I've just been able to reveal a couple of the Ha flares in the galaxy outer core (at about the 5 o'clock position), but clearly would need much more than 5 hours Ha data, also not captured during a bright Moon phase, to show these better. Thanks for looking.

I'm looking foward to lockdown ending and getting over to Seething to see that Stowaway of yours in the flesh - envious, or what....

I'm an AP1200 mount owner, which I purchased on the recommendation of my astro friend and mentor who also owns one. More to the OP's question, my mentor also owns a 178 Starfire, which is a truly gorgeous scope. My friend is primarily a solar system imager (solar, lunar and planetary). When I owned a 10" Meade LX200 we ran some comparative tests on the lunar Copernicus crater and there really wasn't much between them, so that 7" clear aperture APO certainly performed as well as my 10" centrally obstructed SCT. It's a fabulous visual scope providing gorgeous lunar, planetary and WL solar views. I'm sure (hope so anyway) that he won't mind me sharing this, so for anyone interested here is a pic from a few years ago of his 178 riding on his C14. He also uses the etalon off his Coronado 90 for solar Ha views and images off the 178.

Congrats to the winners.

Snap 🙂

I don't have the HiTec astro DC Focuser, but is this what you need? http://www.hitecastro.co.uk/index.php/support/item/hitecdcfocus2-software-download-version-1-3-copy.html

Well here is my first attempt at one of these IKO challenges. I see many suberb versions already, which was a little daugnting, but once I started looking at this excellent data, I was encouraged to keep trying. Apart froma final HLVG step in PS the data was combined and all processing done in ImagesPlus (IP) Main steps were: Crop edges to remove stacking artefacts Combine HaRGB using IP's mix LRGB tool, mapping Ha to R at 50%. ArcSinH stretch Colour balance to neutralise background Addtional Hybrid ArcSinH stretch Noise reduction using Frequency Filter Low Pass with inverted luminance mask Curves to brighten galaxy without lifting the background Open and crop the luminance data using same crop settings as for the HaRGB combine image AcrSinH stretch Feature Mask tool to create separate stars and galaxy layers Mutiscale decomposition tool to sharpen galaxy only layer Noise reduction to galaxy layer using Frequency Filter Low Pass with inverted luminance mask Recombine luminance galaxy layer and stars layer Add Luminance to HaRGB layer Save LHaRGB combination as TIFF Open TIFF in PS(CS2) Apply HLVG (strong) to remove green cast in corners (NB I probably should have done this on the HaRGB layer before adding Lum, but I didn't want to go back and forth between PS and IP) Save as TIFF and JPEG I had another look at the data and decided to use the Ha mapped to red at 100%. I also paid a bit more attention to the overal colour balance to try to preseve some of the blue in the galaxy arms. The luminance data was then applied as Lab Lum at 50% rather than straight Lum as I felt that this preserved the colours a tab better, giving a softer blend in the star forming Ha regions. Hopefully the differences with the additional Ha are subtle, but noticable. Anyway, here is my V2.... Thanks for looking.

After a very helpful discussion with @peter shah a couple of weeks ago and too many to count failed processing attempts to 'fix' or at least control the halo around Alnitak, I have finally managed to produce something that is just about passable to my low standards. The post processing was done in Affinity Photo, comprising probably hundreds of small iterative colour adjustments to the double rind at the halos edges together with brightness & contrast adjustments to the main core of the halo. Lastly I used the red channel as a 50% luminance mask, which further helped to mask (no pun intended) the worst of the many rather crude adjustments that I'd applied. Clearly the halo around Alnitak is still very visible, but I've taken it as far as my limited skills allow, so hopefully it doesn't dominate the image quite as badly as it before. I have also ordered a set of Chroma LRGB filters (~3 weeks back order), in the hope (🤞) that they will perform better on bright stars, than my existing Astronomic Type 2c LRGB set.

Dave, it's really good to see this fine image after all the issues you had getting your rig configured with the new camera. Very nice for just 2 hours of data and good luck with the RGB add, as my blue and green had horrible halos around the 2 bright belt stars, Alnitak in particular.

Hi @The Trubble Telescope, welcome to the forum and also welcome to the 'I forgot to turn off the mount tracking' club. Your horror story is very similar to my own experience, soon after I set up my new observatory back in 2016. After a couple of days poor weather I was itching to get out under the stars, but when I tried, I too found my C14 jammed in the rafters. The mount was no longer tracking as it had wound the 'Y' cable that serves both axes around the mount, until it tore in half cutting the power as seen below.... It took me a few hours to reconnect all the coloured cables, so that it worked again and about £180 to buy a new cable from Astro-Physics, which I had a cousin bring over from USA when she visited a couple of months later. I hope that you can get your mount fixed without too much expense, or delay.