M27 - RGB & LRGB Comparison

[AndyUK]

Hi all - Well I must be just about the only person who was looking the wrong way last night . It's not often we get the chance to see a nice bright Supernova! Hopefully next time...

I'm still trying to get to grips with the Atik 314L+ and still struggling in some areas, but tonight I thought I'd have a crack at M27. After making the mistake last time of taking luminance on M13 (and also binning the RGB), I decided to take straight RGB - no Luminance and no binning.

I still have no real idea about assessing / calculating exposures, but now I'm getting to grips with Artemis Capture, I'm actually very impressed with how simple it is and how sensitive the camera is - The two combined make it very easy to frame the object, although fine tuning focusing with FWHM (after using a B mask) will take a bit more practice.

As an experiment, when processing the subs, I also stacked ALL the RGB subs in one additional stack and created a false luminance stack out of it and then added this as a luminance layer to the separate R, G and B channels. I'm sure I haven't just discovered this, but I'd be very interested in anyone's preference (and obviously comments...!)

Exposure details: MN190/Atik 314L+, 12x5 mins each R, G and B, 50 Bias, aligned stacked in DSS, levels/RGB alignment and RGB combine in Maxim, levels/curves/various Noels actions in CS5.

[ncjunk]

First up... nice set of images!

I prefered the second to begin with but then when looking at them more thought they both lacked detail. By this I mean that the second seems sharper but appears a bit harsh compared to the first.

Then looking at them both they lack a bit of detail in the "clouds" in the central region and appear to have equal levels of detail. But no 2 appears sharper....

So i'm not sure which I prefer now...

By the way there great images this is just being a bit picky for the sake of it!

[Crunchard]

Both are lovely images.

Out of the two I prefer the 2nd, for me it is definitely sharper.

[johnh]

The first one makes the faint outer material more visible.

John.

[AndyUK]

Cheers All - The second is the one with the "false luminance" layer, so (sort of) has an extra 36 subs included, which should mean it being possible to pull out a little more detail that the first (I think?), but I hadn't noticed the faint outer detail in the first one... (thanks John!)

I think the lack of detail could be down to a number of things, not least of which is my lacking in processing skills(!) although as I've noted, I'm not 100% sure I've got focusing pegged yet, and of course there's also possibly guiding errors (and of course collimation, although I did check with a Hotech during setup). So many possibilties for something to go wrong...

Oh well, back to the drawing board / CS5 again...!

[ncjunk]

I wouldn't have said back to the drawing board!

That Atik is looking good so far...keep em coming!

[peter shah]

i like the first one, plain old RGB but the core detail pops out of the second,

[AndyUK]

Hi Neil - Yes, the Atik is looking very good... It's me that's not! I WILL get there though - I did have momentary thoughts that an OSC might be (slightly) less complex, but I seem to have pegged the RGB aligning and combining (I think!). It's the focus / collimation / guiding and post-processing in general I need to concentrate on (with a priority on the first 3 for now - I thought I had all those sorted when using the DSLR... ). It is fun seeing the mono images come together to create a colour image though !

Thanks for the comment Peter - I've just had another go at reprocessing with a false luminance layer to see if I could get the extra detail of the first with the core detail of the second - Sadly I couldn't get the core detail to come through but I think it is slightly better than the first

[MikeWilson]

Nice work Andy!

How about an unbinned lum layer with a light pollution filter attached?

[SlipperySquid]

Great picture Andy! This last one to me anyway, is the best of the bunch! You have managed to get rid of the slight red gradient you had on the second image the star colours are nice and the image is lovely and sharp. The faint outer halo's are starting to come through nicely.

Well done fella.

Matt.

[Uranium235]

Glad to see youre getting there with the Atik, it takes a bit of getting used to. Like you I was crying out for the simplicity of OSC for the first couple of months. But i dont think ive ever tried creating an L layer the way you did though, it seems to have done the job nicely

Hmmmm.... have you thought about using your Ha filter to add more detail to the red channel?

[AndyUK]

Cheers Mike

How about an unbinned lum layer with a light pollution filter attached?

I've been debating this for a while - As an LP filter creates a slight colour cast, I'd really have to use it on all filters, and I didn't really want to add another light-gathering dust trap into the mix (aside from which, it would cost another £150!). The idea of using R,G and B for a false luminance layer is that the filters are all UV blocked anyway, and there's a spectrum gap between R and G which neatly takes out the LP (I think and hope).

@ Matt - Thanks! It might be nice to get some more subs on this just to see how much detail I can REALLY pull through on it - I'm sure it can be sharper too, but I'm glad that you think the reprocess was worth the effort...

@ Uranium

Like you I was crying out for the simplicity of OSC for the first couple of months

I'm glad it's not just me then! I'm sure I'll get over it (well, I have no choice - SWMBO would make my life a misery if I mentioned I wanted to switch... especially as it would have to be a 4000! ). I think it was Dennis that first mentioned using RGB as a false luminance...

It's very interesting you should mention adding Ha - When I went out at 02:45 (end of the "B" run), I was hoping I might be able to squeeze in 30 mins of Ha, but sadly not - it was already starting to get light. And then this morning I saw Nadeem's Ha of M27... I did think of asking him if he wanted my subs, but to be honest, they don't look to be in the same league as his Ha subs! Still, maybe I'll try some later (it'll be good practice at adding Ha into the L layer if nothing else!)

[cloudbuster]

hi andy. i got out last night, but had problems, so alas no images! love these images by the way....especially the 2nd one.

cheers

bob

[roundycat]

The first one for me. The second has too much contrast/saturation and sharpening. If the eggy stars could be rounded off it would probably look sharper without any sharpening. This one http://stargazerslounge.com/imaging-deep-sky/144376-first-picture-ages.html also looks overdone on the sharpening front because I didn't mask off the stars.

Try a duplicate layer set to Darken and move it pixel at a time to see the effect on the star shape.

Dennis

[Deneb]

I was actually going to ask you Andy could I borrow some of your subs, but was relunctant to. Or if someone could merge me & Andy's data together using registar...

Nadeem.

[AndyUK]

Hi Bob - I'm sorry you had problems last night . It seemed as though, of the two nights, last night the seeing was better... Hope you get it sorted for next time (Is it anything we can help with?)

Cheers Dennis - Thanks for the tip - I'll have another go. I wish I knew more about what all those layer options do and when to use them... . If that will salvage those stars even just a little, I'll be extremely chuffed!

By the way, that's an abolsutely BEAUTIFUL Ha image of the NA/Pelican nebulae - I hope you do manage to get the SII and OIII for it as it'll be absolutely stunning...!

Nadeem - Sure no worries, you can certainly have a copy of them if you want, but they're a bit, um, variable(?) I'll upload them into a dropbox folder for you - I think I already have one shared out to you anyway (with M13 subs?).

[shaunster]

They all show good detail Andy but to me they all look way over processed, I much much prefer a natural look

[AndyUK]

Cheers Shaunster - Our telepathy chips must be in tune at the moment - In light of the tip from Dennis, I'm having another crack at reprocessing and just as I received your post, I was just making exactly that decision! A more natural V4 will be up shortly...

[AndyUK]

Thanks to the darken layer tip (thanks Dennis - I'll remember that one!) and in consideration of Shaunster's comment (which I must, I was also coming around to as well), here's a much more natural processing. Basically I've done exactly the same as before but nowhere near as agressively - I think it's brought out more of the fainter shell than before, but I'm going to leave this alone now (I could re-process forever!). Maybe if / when I get some more subs, I'll have another go and see if I can get some better detail.

[roundycat]

looking a lot nicer.

Dennis

[fatwoul]

Agreed, looks a lot more natural and "realistic". Good tip with the false L, Andy, I'd not heard that one.

Shouldn't be too long before I get my CCD so we can start sharing data if that's helpful. It'd be good for me, cos I often struggle to settle on a target, so working with other people would be good (so long as the targets aren't to the south!)

[AndyUK]

Thanks Dennis - I realised (when reprocessing to include your darkness layer) that I'd been trying to push what I had to compensate for the lack of subs... Although I (personally) quite liked the 2nd version, I noticed that this was at the expense of the outer shell detail... I'm sure it could probably be better, but it will be a lot easier with at least double (if not triple) the subs.

@ Fatwoul - You can thank Dennis for the idea of using the RGB's to create the false luminance... It certainly seems pretty logical to me, and it also saves having to buy/use an LP filter (), but I suspect it probably works best as long as the RGB subs are the same exposures. Still, there appears to be an option when combining in Maxim to configure the RGB according to user-defined ratios, so as and when I get around to doing a G2V star callibration test, I'll try playing around with those...

I'm very much up for sharing data though, but I too often struggle for a target as my views from home are also pretty limited. For me North to East is pretty good, and above 45 degrees South is okay, but South West round to North West isn't very good at all. Still give me a shout if you've got anything in mind and I'll see what I can do - I have one dark site I can go to and I'm working on another one (which will be most excellent for all quadrants as long as it's not too windy!)