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Best CCD setup to start with?

kirkster501

By kirkster501
in Discussions - Cameras

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perfrej

perfrej

Posted
Posted

Pixel size from the camera specs, in um. A KAF-8300 is 5.4 x 5.4 um. To get it in arcseconds per pixel you first multiply it by 206 and then divide by the focal length. The seeing usually fluctuates at around 2-3 arcseconds so you can easily see the total over-kill of using 0.5 arcseconds per pixel resolution ;)

An 8300, then, at FL 1000mm comes in at 5.4 x 206 / 1000, or 1.11"/px. A bit on the high side but quite OK. Get yourself a Planewave CDK-17 with its 2938mm focal length and the 8300 would give you 0.38"/px. Totally useless. Apart from the pure aperture you gain very little over a Skywatcher 190MN (the CDK is 22 times as expensive). Jonas Grinde made a comparison between his image of NGC206 (a global cluster within M31) taken with a 190MN and a QSI 583 (8300-based) and someone with much better skies and instrument. The difference was not that big.

So, aim for 1-2"/px and you have the stuff! Binning is just not the way to go. I can also add that the later models of 8300-based cameras have much better read electronics that do the earlier ones. Specifically, my QSI-683 read a base BIAS of 240 ADU while my older SBIG ST-8300M reads 1100. Not a pure noise measurement, but the BIAS is a bit distributed. I think the 8300 is about as good as it gets for the money. Sony, albeit lower in noise generally, don't make that many larger format monochrome chips...

/per

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ollypenrice

ollypenrice

Posted
Posted

I was just typing much the same material as Tim when it vanished. Mono is faster and Baader filters are parfocal (even at F3.9) so you can script a sequence easily. If you get the colour in Bin2 it is faster still.

You cannot compare a QHY with an Atik, as Tim says. With a 314L your only limitation is chip size but on that chip you can capture data to make a world class image, and I mean world class bar nothing. Sorry but this is never going to happen on a QHY OSC. I'll let Tim comment as he has done because I've been told off before for not thinking much of QHY quality!

Personally I'd only go for an 8300 chip in a premium camera costing a lot of money. The chip needs it. QSI and upwards, yes, the rest no.

When you choose a camera forget the bunkum of 'How many megapixels' and look at noise and sensitivity.

Olly

http://ollypenrice.s...39556&k=FGgG233

Edit; Tim's Crab Nebula; how to win an argument without saying a word!!!

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Gonzo

Gonzo

Posted
Posted

SO..........THE BIG QUESTION

For us newbie folk should we be going mono/osc or dslr.......? and what kind of money should our newbie folk be prepared to spend....?

That is the question.

cheers Kev

I would be ready to spend around £1k in a mono CCD, the Atik 314L+ would be my first choice, but I also have the SXVR-H9 in mind.

Will be more than happy to only do mono pictures :)

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ollypenrice

ollypenrice

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OK, my view; DSLR is a blind alley. It's cheap, you get a big chip and you get a lot of noise and not much signal. Once you start modding them at lots of trouble and expense I feel you'd have done better to get into CCD. Plenty of scope for disagreement with this view, I know. Some modded DSLR images do get CCD like results but this is in hyper-fast systems which bring their own issues. If you can afford a CCD rig, go for it.

Mono is faster and more flexible than CCD, opens up the moonlit times, can do narrowband effectively, but many targets can be captured well by OSC. Some cannot. I've used both extensively and like both, but if you have only one I'd say mono.

Olly

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ollypenrice

ollypenrice

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With my Megrez 72, an Atik 314L+ would give me 3.07"/px , is that acceptable?

I think it's perfectly OK. I've literally never had anybody comment to the effect that my images are oversampled, as most of them are. (Those with Yves and the ODK are undersampled.) I bet they start to notice now that I've said this, though...

Olly

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ollypenrice

ollypenrice

Posted
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Just as evidence, the most APOD-winning rig of all time has surely been the 11 meg Kodak chip in the Takahashi FSQ106. 3.5 arcseconds per pixel. But that's rubbish, no?

It doesn't seem to be!

http://apod.nasa.gov/apod/ap120828.html

http://apod.nasa.gov/apod/ap121101.html

There are dozens of similar examples at the highest level.

Olly

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triggertrevor

triggertrevor

Posted
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cheers for the input guys.

I've just been looking at the atik titan as i can use this as a guide cam and use my lumix G5 until i have the pennys for a good ccd then when i buy a good ccd i already have a guide cam. win win in my book.?

cheers Kev

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Gonzo

Gonzo

Posted
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I have only just started using it as a guider, can't really comment on it yet. However, I can say that's a cracking little camera. I used it in my house in the evening (read: in near darkness), and the quality of the pictures(/video) is stunning.

Compare to my modded spc900 (yesyes style) it's night and day...

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Gina

Gina

Posted
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The QHY5 makes an excellent guide camera, I've found. ST80 plus QHY5 and PHD seem to be the preferred guide system used by very many astro imagers.

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Tim

Tim

Posted
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I've not used a QHY5, I know a lot of people do. I used to run a DSI pro which was very sensitive, and then I got a lodestar, WOW! Worth every penny. It's good enough for me to guide at 2800mm, f10, through a tiny pick off prism in an OAG.

Might upset the cart here, but, the new wave of astro cameras with small pixels can produce nice enough pictures when they are binned 2x2, particularly if you drizzle when stacking them. This way you get even greater sensitivity and speed of collection. It's not twice as fast as unbinned, and I've never properly done a 1x1 vs 2x2 ADU test for a given time, but I should think you gain at least 30% greater response by binning.

Binning 2x2 on my H9 camera wasn't that pretty, but on the 428ex and 460ex you can still get a smooth enough image thanks to the dinky enough pixels. I am currently, (if the sky ever clears again), running 1x1 oversampled subs head to head against 2x2 on M51, which will be a decent test of response, and ability to capture wispy small/fine details. Might be interesting results from that.

My crab image from last year was binned 2x2 ;)

Cheers

Tim

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davew

davew

Posted
Posted

As I'm away at star camp I've missed this thread. but I have a question......

What is wrong with Moravian cameras ? I hear that only the QSI upwards are any good, unless that is it's an Atik. Can someone tell me about Moravians and their failings ?

Also. One of the best International imagers is using a QHY. He seems to beat most of us.

Thank you,

Dave.

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perfrej

perfrej

Posted
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Ah, Moravian Instruments! Definitely on my short-list. It is difficult to find any decent reviews but the specs and mechanics look allright. Perhaps their 16803-based camera is good... Anyone who knows?

Olly, 3.5 is great, but over-sampling at 0.5 is a total catastrophy ;)

/per

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davew

davew

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I can't tell you about the 16803 but I know the G2 series with the 8300 chip are really well made cameras with fine electronics and a shutter that just works !

They also make all the bits that people rave about with other manufacturers and have a Maxim like capture and process program. Off axis guiders, built in or separate filter wheels and adapters to fit various setups.

It's most unfortunate I can't tell anyone what their back up is like. Mine hasn't missed a beat in almost 2.5 years.

They should not be dismissed in quite the manner they appear to be.

Dave.

PS. It's snowing in Kielder :)

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ollypenrice

ollypenrice

Posted
Posted

As I'm away at star camp I've missed this thread. but I have a question......

What is wrong with Moravian cameras ? I hear that only the QSI upwards are any good, unless that is it's an Atik. Can someone tell me about Moravians and their failings ?

Also. One of the best International imagers is using a QHY. He seems to beat most of us.

Thank you,

Dave.

I've heard nothing bad about Moravian and am entirely open minded. It's odd that we don't see more of them.

I've heard lots of bad about QHY and seen a fair bit first hand so I'm less open minded. Could you link us to the guy you're talking about?

Olly

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