Been chooking a fair bit since last Wednesday until yesterday on and off between rain, clouds, sucker holes, moon and testing mods on the G11. Somehow I still managed to get a bit over 30h of data with the old Q and a QHY9 in 10min exposures. I did the blend in PixInsight to get colors that I like so there's a bit of green and a bit of pink that I left in there too so I didn't end up with a blue/orange with white stars pic that I really hate.
The colours are lovely. Your 30 hours at the helm have produced a very smooth and definite result.
(To the unbelievers: We just don't understand the popular terror of seeing green in an SHO image. If the celestial reality contains areas of relatively fresh gas with not too much hard ultra-violet, then compared with the rest of the image, those particular areas with have predominantly H-alpha emission without too much OIII or SII emission, and it should, must, be green. If it isn't, there's a mistake, you're not being true to what's up there. Marc's got it exactly right: parts of this image are nowhere near as violent as say bits of the Magellanic clouds for example).
One to print really big and put on the wall. Bravo!
The colours are lovely. Your 30 hours at the helm have produced a very smooth and definite result.
(To the unbelievers: We just don't understand the popular terror of seeing green in an SHO image. If the celestial reality contains areas of relatively fresh gas with not too much hard ultra-violet, then compared with the rest of the image, those particular areas with have predominantly H-alpha emission without too much OIII or SII emission, and it should, must, be green. If it isn't, there's a mistake, you're not being true to what's up there. Marc's got it exactly right: parts of this image are nowhere near as violent as say bits of the Magellanic clouds for example).
One to print really big and put on the wall. Bravo!
Best,
MnT
Thanks a lot mate. Good write-up. Go greens!
Quote:
Originally Posted by Ryderscope
A very fine piece of work Marc that moves and swirls between the different elements in a classic fashion. The colour pallet works extremely well
Thanks Rodney. Took a few iterations. I'm really rusted with color processing three channels.
Quote:
Originally Posted by Atmos
You JUST caught the PN along the lower left edge
Nicely done overall Marc
Thanks Colin. Yeah at first I though it was a water droplet or something that wasn't flat fielded correctly then realised I should keep it so I managed to salvage it after the combine. Barely. Maybe I'll go look at it with the CN-212 when the mount is up to scratch.
Quote:
Originally Posted by marc4darkskies
A beautiful and, dare I say, restrained image Marc! Always appreciate images without over-the-top colours!
Thanks Marc. I don't deconv/sharpen/denoise my FSQ shots anymore and haven't for a long while. Instead I try to keep the focus spot on during the data collection, try to guide as best as I can sub pixel and dither a lot. It's a realively light weight fast scope stiff and compact enough to do that. I also found that if I try to sharpen anything I lose all the details and the smallest stars. So I gave up on this and don't do it anymore. I don't use star masks or star removals either. There are way too many stars in these shots and the tiny ones are just above the noise level. I can't possibly manage the star profiles in processing that many stars so I only play with colors. Nothing else.
Solid image Marc, well done, well framed and great detail!
Quote:
Originally Posted by Placidus
(To the unbelievers: We just don't understand the popular terror of seeing green in an SHO image. If the celestial reality contains areas of relatively fresh gas with not too much hard ultra-violet, then compared with the rest of the image, those particular areas with have predominantly H-alpha emission without too much OIII or SII emission, and it should, must, be green. If it isn't, there's a mistake, you're not being true to what's up there. Marc's got it exactly right: parts of this image are nowhere near as violent as say bits of the Magellanic clouds for example).
MnT
As to the above, (and with apologies for hijacking your thread) - if Ha is red ie: H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm - how it can possibly be green?
HST scientists simply assign Ha to the green channel, O3 to Blue and S2 to red simply for identification purposes, as it's easier to see the makeup of individual gases when assigned to these tones & blended than if they were all in monochrome.
To quote JP Metsavanio - What is the truth then?
"Deep space targets are generally so dim, that human eye is not capable to see any colours from them. Closest to real colours is the RGB image, if colors are balanced correctly.
Usually a pure white Star is used to measure a correct colour balance between Red, Green and Blue data.
Next closest is the H-aRGB mix, where H-alpha filtered image is used to boost contrast and details in image. It tends to distort the Red balance in image though.
Third, in reality order, is a Narrowband mixture, where different channels are mapped to visible colours as closely as possible by the wavelengths.
Ha is mapped to Red with about 20% S-II, O-III is Green and the Blue is mixed from O-III and about 15% H-alpha to compensate missing H-beta.
The Hubble palette is least realistic colour scheme. It's made famous by wonderful pictures from the Hubble Telescope. This palette is developed to maximise visual difference between different ionised Elements in Nebula. Even though it's used in scientific purposes, it's beautiful as well. I use HST-palette for aesthetic reasons only, with that tool I'm able to reveal some of the hidden beauty.
Another good reason to use it is, that it's a de facto standard and makes possible to compare images from different narrowband imagers."
Now don't get me started on CFHT colour palette which is different again!
Point being, there are NO rules in Narrowband imaging colour choices. There are accepted "standards" eg: HST, CFHT etc. but that doesn't necessarily mean correct, aesthetically pleasing or scientifically accurate colours.
So then it's simply a matter of aesthetics and that which pleases the creators eye. If you like vivid, bold eye-catching palettes then go for it, or if you prefer blue and green without a colour in between and purple stars then that's your choice too!
Solid image Marc, well done, well framed and great detail!
As to the above, (and with apologies for hijacking your thread) - if Ha is red ie: H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm - how it can possibly be green?
HST scientists simply assign Ha to the green channel, O3 to Blue and S2 to red simply for identification purposes, as it's easier to see the makeup of individual gases when assigned to these tones & blended than if they were all in monochrome.
To quote JP Metsavanio - What is the truth then?
"Deep space targets are generally so dim, that human eye is not capable to see any colours from them. Closest to real colours is the RGB image, if colors are balanced correctly.
Usually a pure white Star is used to measure a correct colour balance between Red, Green and Blue data.
Next closest is the H-aRGB mix, where H-alpha filtered image is used to boost contrast and details in image. It tends to distort the Red balance in image though.
Third, in reality order, is a Narrowband mixture, where different channels are mapped to visible colours as closely as possible by the wavelengths.
Ha is mapped to Red with about 20% S-II, O-III is Green and the Blue is mixed from O-III and about 15% H-alpha to compensate missing H-beta.
The Hubble palette is least realistic colour scheme. It's made famous by wonderful pictures from the Hubble Telescope. This palette is developed to maximise visual difference between different ionised Elements in Nebula. Even though it's used in scientific purposes, it's beautiful as well. I use HST-palette for aesthetic reasons only, with that tool I'm able to reveal some of the hidden beauty.
Another good reason to use it is, that it's a de facto standard and makes possible to compare images from different narrowband imagers."
Now don't get me started on CFHT colour palette which is different again!
Point being, there are NO rules in Narrowband imaging colour choices. There are accepted "standards" eg: HST, CFHT etc. but that doesn't necessarily mean correct, aesthetically pleasing or scientifically accurate colours.
So then it's simply a matter of aesthetics and that which pleases the creators eye. If you like vivid, bold eye-catching palettes then go for it, or if you prefer blue and green without a colour in between and purple stars then that's your choice too!
If you say so Sensei.
Quote:
Originally Posted by gregbradley
That turned out well. 30 hours - sacre bleu!
That's a long time for you and a long time for me.
Greg.
Thanks Greg. Actually I did 15h of Sii by mistake. But I meant the Oiii
Great image Marc - well done
On another note - I too have seen the green in the chicken https://flic.kr/p/DYtZp9 roast chicken with a side of salad? 🤔
Cheers
Russ
Oh wow! Top shot... and we got the salad in the same spots. Maybe it's real Love the image scale. The central area with the bok globules is on my todo list as well with the CN-212 once I have my mount fixed. Thanks mate.
What is the apparent object on the left side of the frame a small way up from the bottom? Looks like a planetary nebula or did you put that there to trick me? I wasn't able to find a reference to it in Starry night although I could navigate to that area from your image. I even tried astrometry.net.
Thanks Marc. What a field. There is so much depth there. A lot of dedicated time to get to that level of detail .
Looks like the Losmandy is on track.
Thanks Ray. I've received the new bearings yesterday and I have the new couplers being machined this week out of stainless steel which is stiffer than brass so probably picking them up Friday. I also managed to source all the various greases and lubes I need.
The gearbox changes has made a massive improvement in tracking. I wasn't too sure about it TBH at first but the early measurements I did in pemPRO really surprised me. There is also no backlash in RA or DEC now. Because everything is tighter I'm able to lock the motors and gearboxes in line in relation to the worm axis in a repeatable way. There is no more slack.
One of the very obvious thing I noticed was the drop in noise levels. Outdoors I can't hear the mount slewing because when all the gears and couplings are square and in the right position you don't get that cyclical sound due to excentricity or stress.
The other night when I was shooting the chicken Oiii for a few seconds I got confused because I couldn't graph the RA and thought it was off the charts on the PHD windows until I got the first bump and realised it was flat lining under the DEC
Now I'm working on getting rid of the remaining PE which is in the couplers alignments and bearings. Change of lube on the worm assembly did a noticeable improvement as well in smoothness and I was able to tighten the meshing as a result without binding.
What works at a given temperature doesn't necessarily replicate at lower ones so I'm now looking into spring loading what I can. The first thing is trying to put a small belleville washer between the outer worm bearing and the worm. That would allow some play axially with temperature changes and minimise stress on the R4 bearings. I found one of the high precision RA bearing was damaged over the years. They don't like lateral stress. When the bearing is damaged you get a spike during one revolution of the worm. It was 0.8 second of arc on the worm frequency spectrum. Everything adds up.
I'm also looking into preloading the worm meshing to compensate for changes in temperature. Will start with DEC then if it works translate to RA.
When I have everything working I can start imaging with the CN-212 again. I'd like to get the mount under 1.5 or 1 arcsec peak to peak. The AO can pick up the rest if needed but I'd like to get everything as close as possible mechanically first.
and a cigar 
I wasn't able to find a reference to it in Starry night although I could navigate to that area from your image. I even tried astrometry.net.
