EOS CLS Test - ETA Carinae Nebula - 4th May

[Screwdriverone (Chris)]

Hi All,

I was mucking around with the new EOS CLS Clip filter on Friday night, having a play with it and seeing what difference it made to things.

While having a fullish moon hanging around is not ideal, it did let me get some subs from Eta Carina and have a go at processing out the blue cast on the images. God knows I need some processing practice.

So, after collecting a meagre 20 mins at ISO 1600 for 30 secs each sub (yes, I know this isnt enough data and it shows) and keeping in mind it WAS a full moon, I simply stacked these in Nebulosity and practiced stretching the data and fixing the colour channels to try and get things more natural.

Something I noticed straight away from the subs is just how much MORE nebulosity comes through and as you will see from the image, there are even some bok globules visible where I havent been seeing them before.

Not my best image, I'm sure, but an interesting start and something that has helped me drive Nebulosity and Photoshop CS3 with ONLY the levels adjustments and a touch of curves and a smidgen of unsharp mask to try and tease out some details from what is a relatively short exposure stack.

Main thing is, I am not getting cross at myself anymore for not being able to "pull" an image out of what is basically bad data due to moon/vignetting/short subs/noise etc and I am treating the data as a learning process more to figure out how to stretch it and not overcook it by clipping it to death. Keeping a sharp eye on the histogram helped me no end and I ACTUALLY stretched each RGB channel separately rather than do them all at the same time which seems to be the key....I think?

Anyhow, its got a lot of noise from the high bias of having the full moon and no flats etc. I did simply capture these with ICNR on in the camera to save me from taking darks during the test.

Please take a look and let me know your thoughts, I know its not bragworthy, but I think its a step forward for me because now I have a better (read CALMER) understanding of what I need to capture to be able to process data better as well as understand the foibles of the histogram and lastly, it seems the EOS CLS clip lets my little unmodded camera pick up more of the nebulous goodness out there.

This may be a bit too red? I tried to keep it balanced, but welcome any suggestions on how to process it a bit better (of course with better data, but still....)

Link is here as I wasnt happy with the cruddy way the resize squared all my stars, so this is a 7MB JPG file at the other end of this link, my apologies for those on slow links.

https://www.dropbox.com/s/lh28wc80c3...ilter-test.jpg

Thanks for stopping by for a read of my little essay....sorry if its a bit long, but I am happy with how things are progressing now.

Cheers

Chris

[midnight (Darrin)]

Chris, it certainly looked better than I thought it would after reading your notes. There's certainly promise in this.

I've borrowed a CLS filter for my 40D and dumped it after only 2 nights because of the horrible colour. But in hindsight, this may have been silly of me and not understanding correctly the function of the clip filter and how to compensate for it.

Reading with interest and I might just go and get that CLS filter back.

Good luck!

Darrin...

[Screwdriverone (Chris)]

Thanks Darrin,

Yes, the blue cast is disconcerting, a single sub shows it up a lot!

The thing is, even with the full moon out, I got more Ha response than ever before even at only ISO 800 for these ETA subs and I also tried the Lagoon Nebula (M8) at 60 secs / ISO 1600.

I have attached a single 60 sec sub from M8 to show you what I mean, the expanse of the Lagoon is visible even through the blue.

Not bad for an unmodded DSLR, I am going to give M8 a process with the 10 minutes I have and see if I can tease it out as well.

All I have done to this attached image is resized to 1024 x 629 and saved it for under 200kb, NO processing applied to it.

Looks like the CLS makes a big difference, I know the Hutech IDAS LPS doesnt give the blue tinge, but I will have to live with processing it out as I was too impatient to wait for an OS delivery and I might try the custom white balance trick as well to remove the blue next time.

Cheers

Chris

[strongmanmike (Michael)]

Ah the trials and tribulations we endure to collect old photons....

Someone should blow super moons up

Nice result none the less Chris

Mike

[Screwdriverone (Chris)]

Thanks Mike,

I wasnt expecting too much considering the full moon and I hadnt tried the filter before, but it is good to know it seems to improve the response on nebulae for an unmodded camera. Now I just have to figure out the best exposure/ISO/noise balance and then go nuts on capturing LOTS of subs....

Its good to get some excitement back after trialling different things and having some issues trying to process.....always learning it seems....

Cheers

Chris

[RobF (Rob)]

Great to hear Chris. I always felt I got much better signal to noise from suburbia with my IDAS filter in place. They are known for being relatively easy to process colour casts out too. You seem to have very natural colour in your processed Eta test shot.

[Screwdriverone (Chris)]

Cheers Rob,

I think eta is a good yard stick to play with this on, I sort of remember what it looks like in my head and I think it was Jeanette who reminded me a while back to keep an eye always on the histogram, gently, gently....

I had much better success with aligning the colours by processing the CLS image stack on the individual RGB channels so I didnt smash one that was hidden behind the other and this I think led me to seeing how close I was getting.....

Its fun again now I can understand a little more of what I should be doing and how to get there. As I said, this was simply Nebulosity stacked and then passed straight to PS CS3 only. I can live with the outer extremeties of noise which I know are from the vignetting (not as bad now) but are there because of my stretch/curves playing and not much data. Knowing this certainly defuses my need to try and eliminate it and screw up the rest of the good bits.....that was my major fault before I think.

Just playing with my Lagoon M8 data now, only 10 mins, but its looking similar in expanse to the faint nebulous areas shown here on ETA. Certainly cranks the unmodded cam up a notch.

One happy(ier) camper here

Cheers

Chris

[DavidU (Dave)]

Now your cooking Chris ! well done. Great to see results after your frustration a few weeks back.

[Screwdriverone (Chris)]

Frustration David? WHAT frustration? ME? NEVER!

HA HA HA

Thanks for the vote of confidence, what a difference a filter (and a cool head) makes!

I have reset my expectations on minimal data to zero, so anything I can get from subs and processing is a bonus, but I must say, I think I am getting better at this?

Thanks for stopping by

Cheers

Chris