Taking the plunge - first CCD for deep sky?

[rocketandroll]

Hi all

Ok.... I've made the decision to get a full new imaging rig and go the CCD route having done a year of imaging with a DSLR.

I want to go for a colour CCD for the simple reason that I know I will struggle to find the time to capture data to do LRGB or narrowband and will most likely end up with hours of unfinished data sets and no completed images.

I will be using the camera with frac's between 350mm and 600mm focal length mainly but would like to be able to get something with a sensor size that allows me to fit reasonable sized targets in such as the whole of M42/running man etc.

I am also keen not to drop in resolution from my 550D which means small pixel size, ideally <5nm.

My budget is about £2K or so I guess.... would look at second hand cameras if the right one came up but new would be good just for the after-sales support (had a very good experience with Starlight Xpress so far with my guide camera).

So....

what would people's recomendations be?

Thanks!

Ben

[Dave Smith]

Hi Ben

Don't forget that with narrow band imaging you have more opportunities to image. The Moon is not a problem. Also mono cameras are more sensitive.

I have been using an Atik 314L+ (mono) and have been very happy with it. The Sony chips are very low noise.

Dave

[Helen]

Given your criteria, how about an Atik 460 colour http://www.firstligh...atik-460EX.html The pixel size comes in under your limit. On FOV, my combination has fl 590 and this is what The Sky says my coverage of M42 will be

Like you, I wanted a combination which allowed me to get results in one night. I've tried the filter route and do indeed have lots of unfinished data sets, which proved rather frustrating. I'm finding the 460 a joy to use (and my husband has noticed how much less frustrated I am!!). I've posted some of my early results here http://stargazerslounge.com/topic/163219-getting-to-know-my-atik-460-colour-camera/ Most of these are less than an hours worth of exposure (but at f4.8) - the Cocoon is 2.5 hours.

HTH

Helen

[rocketandroll]

Helen

Many thanks for the link and encouragement..... your 'quick' image of the iris is about all the encouragement I need :-) I assume those pics are through the 123 not the 72? Or a bit of both? The M31 image looks quite wide angle for that chip size and 590mm fl? Out of interest... how recently did you buy the camera and scope? FLO's website is listing the FLT123 as 'Customers also bought this' with that camera :-)

I know myself.... and I know my circumstances... and I am unlikely (given this last year and a half's efforts) to be able to commit more than one, maybe two nights to a subject. Being able to set the rig running and capture a few hours on a target during a clear spell... and have something to show for it... is the key thing I'm after.

I don't have dillusions of becoming one of the world greats in astro photography, just want to do it for myself and for the joy of capturing this stuff in some detail and hanging some lovely images on the wall.

At 6mp or so and sub 5nm pixel size that camera looks about bang on what I need, and is about right price wise too.

Anyone else got experience with any other cameras they may want to throw in?

Ben

[ollypenrice]

I'd look no further than the 460 having just spent a couple of nights with the mono verson.

Olly

[Helen]

All my shots were taken with the FLT123, which I bought with the camera in the summer The scope, as well as the camera, is lovely.

As far as the Iris Nebula goes, that shot was taken in less than ideal conditions as there was high cloud and then I got rained on! So I think there's more to come there. It did make me smile a lot when I saw what came out in the stretch though

I love being able to take decent shots in one night, given I live in wet and cloudy Wales!!

Helen

[dmahon]

My budget is about £2K or so I guess.... would look at second hand cameras if the right one came up but new would be good just for the after-sales support (had a very good experience with Starlight Xpress so far with my guide camera).

So....

what would people's recomendations be?

I'd go mono for 4x the resolution, but my recommendation would be SXVR-H694.

[rocketandroll]

See above reasons for NOT going mono :-)

Without a filter I guess the mono camera is way more sensitive... the moment you put a filter in it though it's throwing away most of the photons so isn't as sensitive any more... isn't it?

Tell me... which would produce a better result:

4 X 15 minute exposures on a one-shot colour CCD

1 X 15 minute exposure each of LRGB on a mono CCD

I'd be genuinely interested.... I assumed the former?

My concern is, given the time I have and our intermittent weather, plus this being one of several time consuming hobbies I have... I don't want to HAVE to comit to capturing four sets of data on one subject just to get an image.

If I get 20 10 minute subs on a colour CCD but had planned to get 30 I just get a slightly lower quality copy of the same finished image.... if I have the same failure with a mono using filters I loose a whole data set and end up with no image (or a strangely coloured one at least :-) That's my concern :-)

Plus the extra complexity of a filter system.

I want 'plug and play' to capture brief windows of opportunity for now.

Ben

[stormlv]

See above reasons for NOT going mono :-)

Without a filter I guess the mono camera is way more sensitive... the moment you put a filter in it though it's throwing away most of the photons so isn't as sensitive any more... isn't it?

My definition of CCD sensitivity directly relates to the QE of a chip. In that case sensitivity has nothing to do with the amount of photons a camera gets, but with it's ability to transform those photons into an electrical signal.

If you look at the QE charts of most cameras, you'll see that the QE is a function of the wavelength of light and not of its intensity.

This means that even if you put a filter in front of a mono camera, it's sensitivity won't change - even if you indeed get fewer photons.

Tell me... which would produce a better result:

4 X 15 minute exposures on a one-shot colour CCD

1 X 15 minute exposure each of LRGB on a mono CCD

I'd be genuinely interested.... I assumed the former?

I don't think you're actually comparing apples and oranges here...are you?

On an OSC camera of 10MP let's say...your images will have a "real color resolution" of 2.5MP for Red, 5MP for Green and 2.5MP for Blue.

This means that you should be able to get the same "quality" (except for green) in your images if you had been using a 2.5MP Mono camera and exposed 1 x for red, 2 x for green and 1 x for blue.

In this case the exposure times would obviously be 4x as long for the mono, as it's in your example. However you have to remember that we used a 10MP OSC camera and a 2.5MP mono camera.

If you were to compare an OSC with a mono having the same resolution things would obviously be different.

You could very well do 2x2 binning for a 10MP mono camera and get the same color resolution as an OSC, but in that case, obviously the exposure times for the mono are reduced.

So this is why I say you're not fairly comparing OSC and Mono cameras.

Also to consider is that doing narrowband is a bit trickier with a OSC...

[dmahon]

You need to compare RGB in bin2 for the mono camera against the OSC.

The mono will take 7.5 minutes for every 10 that the OSC takes (the OSC will have more green signal, but there's not much use in that).

[rocketandroll]

Thanks all for the thoughts.... the physics of CCD operation are not my strong point so it's good to get some extra info.

Again, to be honest... I am aware that ultimately better results can be obtained with a mono camera and filters, however, I am also aware there is a lot more work involved in getting that right and there is always the risk of not having enough data for one chanel if an imaging session is cut short.

I've been really happy with the results I've got from DSLR imaging the last couple of years and have progressed in my processing of colour deep sky images... and what I am looking for is a SIMPLER rig with a bit more sensitivity so that I can capture images which I feel happy with in a limited amount of time and just expand on my existing knowledge rather than have to start over.

It may well be that one day I decide to progress on to mono and filters, but for now, it's not the route I want to go down.

I am hoping to get hold of a very fast scope (Officina Stellare Veloce RH200 @F3) next year and that will form the core of a super-fast OSC imaging rig which, coupled with a camera like the Atik 460 should be able to produce some really lovely results in a few hours of imaging on one target.

I guess if there wasn't a niche for people who want/need to use OSC cameras then they wouldn't sell them :-) I consider myself to be one of those people.

Ben

[Helen]

I guess if there wasn't a niche for people who want/need to use OSC cameras then they wouldn't sell them :-) I consider myself to be one of those people.

Ben

There are some excellent imagers in that niche too Ben - SteveL has done the majority of his imaging so far with a OSC (including getting an APOD), and I was chatting to Steve Richards (Steppenwolf) on the weekend and he was saying he much prefers OSC too So we're in good company!

Helen

[stormlv]

Btw, if you do take the Atik (mono or color - doesn't matter), be sure to have a good quality power supply - otherwise as it was for me, you'll get a bit of "extra" noise in the images (compared to when it was powered by a batter pack). It was especially visible when taking short exposures.

There's been some talk on the Atik forum about this, if you're interested.

[rocketandroll]

Thanks all... and I am planning on powering everything off the mains and a 12V converter so it should be fine.

I have been talking with Ian at Ian King and been recomended that the SX version of the same camera, although a teensy bit more pricey, may be a better bet as I can use their slimline OAG and my Lodestar directly with it with less hassle than the Atik.

Will see but I certainly think that chip is the one for me.

Just got to wait till next year when I can afford the OS Veloce it's gonna be attached to and start getting some serious results from it :-) A cooled CCD through a f3 scope should create some wonderful images very fast :-)

Ben

[stormlv]

Just a note, I have the SX filter wheel, the OAG and Lodestar and I've had absolutely no problem to use it with the 460. I really wonder why he said there would be any hassle since the threads on the filter wheel and camera are standard...