First light of my new Atik 460EX - NGC6888

[jmtanous]

Hi,

This is the first light of my Atik 460EX. The camera is a good performer,
the only weakness is the mediocre cooling (~ 25 Dt), probably not a big
issue for most users, but I live in a very warm place.

I was after the oxygen shell that surrounds the Crescent. It was a
challenge for my aperture. I had to take 4h of OIII frames to get it in a
more or less comfortable place to process it.

The image can be found here:
http://tinyurl.com/9odswjc

Feedback, suggestions are always welcome!

Cheers,

Jose

The image details are:

Camera
Atik 460EX

Telescope
Takahashi Epsilon 160

Mount
Orion Atlas

Exposure
25 x 10min for Ha (1x1)
25 x 10min for Oiii (1x1)
Total exposure time: 8h

Processing
Acquired with MaximDL.
Stacked, Stretched, Cropped, Saturated and resampled with Pixinsight

[LDunn1]

Hi, as a fellow 460EX owner I wanted to reply to your post........problem is, I'm actually very inexperienced so am going to struggle to offer any insightful comments, but I'll try.

I've viewed your image full screen size. It might be the jpg processing or the noise, but the graduations (most noticeable in the red) don't look that smooth to my eyes. Now I know that the camera is pretty good with respect to noise, so it must be the jpg processing or the post processing? I'm not sure I have the experience to put my finger on it, maybe it's just the subject with all those stars & the nebula, it might always look like that. I don't know.

It could be me, because I have not viewed many bi colour images, & I struggle a bit with that, just more comfy with mono or RGB or even false colour

You have collected loads of data there in Ha & OIII so both must be pretty sweet as mono's in their own right I guess, & the tracking & focus looks bang on , so it must be just me that is struggling here.

Does any of this observation make sense?

[jmtanous]

Hi,

Thanks for commenting on my image.

You are right about the noise, the problem is not the camera, the issue with the noise is the way I pushed the image. I pushed very hard the data, specially the OIII channel.

The camera produces very clean images (compared to KAF8300), but if you push hard no matter how good the raw data is, you'll bring the noise out.

I might revisit this target this season, but I am tweaking my mount to be able to take 20+ minute images, right now I cannot go further 10m and for some targets is not enough.

Cheers,

Jose

[LDunn1]

Hi Jose, thank you for taking my comments constructively. Bottom line is that your result is still way superior to my own! But I was not judging you against me, but against the best I have seen of the various forums, and I was writing openly, to try & make sense of my own thoughts of what I was seeing - everything was telling me it should be a great result, and yet, somethings not quite right.

After posting, I looked at one of my own results & it also does not match my master image, so I suspect part of the issue is in downsizing & saving as a jpeg. Coupled with the bit of extra noise you mention, & my lack of experience viewing bi colour, I think each little bit conspires against the visual impact. Have you thought about grabbing another 4 hrs in SII & using a false colour on yoru data to better balance the colours?

I have not noticed that much intrusive noise from my camera yet, but maybe I have not pushed the data that hard......oh wait, that is not entirely true - I have noticed that my blue channel was very noisey vs green, which in turn was significantly noisier than the red. I applied Noise Ninja to all 3 channels independantly in an attempt to improve the noise.....BUT I only had 4x300s 2x2bin on each of the 3 colours. I did not shoot darks or flat lights though.

With my experience in mind, maybe it is your OIII data being cyan, which is contributing the noise element, have you thought about running noise ninja on the OIII grey scale first? Maybe it wont help you so much as it did me as you have more data to start with, but might be worth a look.

I guess the other aspect that would help is if you collected some L component & used your exisiting data purely for the colour - that way you can get away with being more aggressive on the noise reduction on the colour channels.......I'm new to mono (LRGB) imaging, & have not tried narrow band at all yet, but I've been shocked at what the L part can add to an image & what you can get away with on the colour channels.......but you probably already know this!

With all this in mind, what is your opinion of the camera? Mine is very very favourable, BUT I am comparing to a DSLR as the 460EX is my first steps into a dedicated astro CCD of any type.

 

[jmtanous]

Hi LDunn1,

Unfortunately I live in a very light polluted place and I cannot use broadband filters, so L filter is a no go for me. I try to avoid noise reduction as much as possible cause I always wipe out some fine details/stars.

This camera is very good for narrow band on short focal length scopes, you should try Ha, you'll be impressed the stuff you can pull out with 10 or 20 minute subs.

Cheers,

Jose

[bwa]

Unfortunately I live in a very light polluted place and I cannot use broadband filters, so L filter is a no go for me.

Jose,

Have you tried narrowband imaging (Ha, Oiii & Sii)?  They are actually fabulous in light polluted areas; probably the only real option for astro-imagers living in medium-large cities.

bwa

[LDunn1]

BWA, that is exactly what Jose has done - he HAS imaged in narrow band - Ha + OIII .

What I was suggesting was to use heavy-ish noise reduction on the colour to combat the noise, & then take luminence for detail, which shoudl be less noisy......BUT Jose has commented that he is imaging from a LP area & cannot shoot wide band (the luminance), so has to shoot NB.......& he can't apply heavy noise reduction on that because it is giving him his detail & colour.

From my own limited experience with the 460EX (& general limited experience in astro full stop), the 460EX does have excellent noise control relative to other options, & the red channel is pretty clean, but the green & even more so the blue, tend to be noiser. So I believe that the noise in Jose's shot is mainly coming from the OIII data.

To Jose - just thinking out loud here - have you tried using your Ha channel blended for Luminance & then set a duplicate of Ha & your OIII data, blended for colour - & apply heavy noise reduction on your colour channels? I don't know how effective this would/would not be, but might be worth a go.

[jmtanous]

BWA, that is exactly what Jose has done - he HAS imaged in narrow band - Ha + OIII .

What I was suggesting was to use heavy-ish noise reduction on the colour to combat the noise, & then take luminence for detail, which shoudl be less noisy......BUT Jose has commented that he is imaging from a LP area & cannot shoot wide band (the luminance), so has to shoot NB.......& he can't apply heavy noise reduction on that because it is giving him his detail & colour.

From my own limited experience with the 460EX (& general limited experience in astro full stop), the 460EX does have excellent noise control relative to other options, & the red channel is pretty clean, but the green & even more so the blue, tend to be noiser. So I believe that the noise in Jose's shot is mainly coming from the OIII data.

To Jose - just thinking out loud here - have you tried using your Ha channel blended for Luminance & then set a duplicate of Ha & your OIII data, blended for colour - & apply heavy noise reduction on your colour channels? I don't know how effective this would/would not be, but might be worth a go.

The reason I pushed hard the OIII channel is to bring out the shell around the nebula. Most of the time you can do what you are suggesting, use Ha as L, then denoise the other channels and 'paint' the L channel with the cleaner color channels. However when the OIII is not correlated with the Ha the results are not good.

In this particular case, the outer shell will not be visible if I use a pure Ha as L component. This details make narrowband imaging very challenging and interesting.

Cheers,

Jose