CCD Camera decisions - Mono vs OSC, FOV, Filter wheel etc...

[riklaunim]

I don't know why but APS-C sized Sony CCDs come only in color versions. Biggest mono they make have the 2/3" size (like the ICX285 in Atik and others). I'm curious why it's so "hard" to make a big mono for them. Even this year super-cool mono - ICX674 and older ICX625 are also 2/3" in size.

[RobH]

If I was forced to choose between my 8300 chipped SXVF H18, and my 285 chipped Atik 16HR, I'd go for the 16HR every time.......in fact, I reckon on being buried with it

Ther 8300 is good, but the 285 knocks it into a cocked hat when it comes to sensitivity and lack of noise.

Re. filters and the 8300 etc, I am having no issues with vignetting at F8 with 1.25 inch filters, and at F6 there is only a small amount which isn't really a problem.

Filter wheels are a must. The idea of shooting one filter per night is great in theory, but in this country you may be waiting a long while to get your colour data!

Cheers

Rob

[AndyUK]

Cheers Rob - I think that's totally decided it for me then - The Atik 314L it is then !

When it comes to shooting one filter per night, I wasn't aware how much more sensitive a CCD is compared to a DSLR - I've certainly changed my tack on that thought now and a filter wheel is now definitely on the list... USB sounds lovely, but I think manual will do me just fine - One less thing to go wrong .

[Psychobilly]

I don't know why but APS-C sized Sony CCDs come only in color versions. Biggest mono they make have the 2/3" size (like the ICX285 in Atik and others). I'm curious why it's so "hard" to make a big mono for them. Even this year super-cool mono - ICX674 and older ICX625 are also 2/3" in size.

Probably not economic... I guess the smaller sensors are all thats required for their intended markets...

[riklaunim]

Probably not economic... I guess the smaller sensors are all thats required for their intended markets...

Well, if they had big mono they could competite with Kodak etc. It's very very odd and IMHO it must be some technological issue that makes production of big mono sensors much harder (read out, shutter?)

[shaunster]

One point if your planning on having all 7 filters in the same wheel then the cheaper 5 position manual wheels wont cut it

[Beyond_Vision]

I have both a QHY8 and a Atik 383 and in all honesty I keep using the QHY8 as it feels simpler to use. No need for 4 sets of flats or more for the filters and also less time spent on combining the data. I know the Mono is more sensitive so less exposure time needed etc but I'm not convinced that the time outways the extra set up and processing time.

I have never had any issues with my QHY8 and make what you will of the results from the following image.

Regards

Kevin

[AndyUK]

Kevin - WOW - That's an absolutely STUNNING image...!

There's certainly no doubting the capabilities of the QHY8 and I note your point that with mono there's a lot more faffing about not only with flats / combining the channels but also they generally seem to be more expensive (after adding everything back in to make it colour again!).

Do I assume you use an LP filter...? And do you do narrowband imaging with the QHY8... or would you reach for the 383 for that?

Shaunster - I haven't REALLY looked into the manual filter wheel too much at the moment - Initial thoughts were to go for a Trutech (7) or Atik (5). It might be nice to have a 7 though as that way I'm assuming the filters could all be stored in-situ(?)

[MikeWilson]

Kevin - WOW - That's an absolutely STUNNING image...!

There's certainly no doubting the capabilities of the QHY8 and I note your point that with mono there's a lot more faffing about not only with flats / combining the channels but also they generally seem to be more expensive (after adding everything back in to make it colour again!).

Do I assume you use an LP filter...? And do you do narrowband imaging with the QHY8... or would you reach for the 383 for that?

Hi Kev,

That really is an amazing capture. I too would like to know what light pollution filter you used and also if it was a 1.25" or 2" filter.

Shaunster - I haven't REALLY looked into the manual filter wheel too much at the moment - Initial thoughts were to go for a Trutech (7) or Atik (5). It might be nice to have a 7 though as that way I'm assuming the filters could all be stored in-situ(?)

A mono camera without filter wheel would probably be a headache to manage. It must be quite convenient to have a filter wheel with all the filters in situ ready for use. The 7-slot may be more futureproof, and it's a shame there's no obvious 7-slot, 2" version.

The OSC cameras like the QHY8 seem to have a resolution disadvantage when it comes to narrowband CCD's, but they're still a significant upgrade from DSLR being approximately twice as sensitive with a higher dynamic range and less noise. The tradeoff especially with the QHY8 is that it's significantly wider (good thing or not depending on your preference) and significantly cheaper (always a good thing) and more convenient.

Maybe it's the hybrid intermediary step between DSLR's and mono CCD's?

Clear skies,

Mike

[Beyond_Vision]

I use a Neodymium Filter with a T thread I find it deals with my light pollution which is mostly Sodium Street Lights and doesn't leave the image with a srong cast as does my CLS filter. I have used the QHY8 for Ha for the above image but as you say the 383 would be better for Narrowband.

Regards

Kevin

[shaunster]

Yeh that truetech wheel looks about the only manual choice for a 7position wheel but its not cheap, at that price I think id just swallow the extra ££ and get the USB wheel

[AndyUK]

Hi Shaunster - I know what you mean... but I'm luddite - Perhaps I'm just a grumpy old git, but (personally) I feel that it's just something else to potentially go wrong... I seem to be a magnet for that type of thing happening!

Thanks for the info, Kevin - If I could have TWO CCD's then it would make life a lot simpler - a 285 chip AND and 8300! As I'd really quite like to have a crack at narrowband, I think the mono 285 will still be my first venture into CCD imaging, but that's certainly not knocking any of the OSC's out there - If I could produce images like your M31 now, I wouldn't be looking at buying anything!

[swag72]

For me that M31 definately throws a spanner into the works regarding a OSC for me. Perhaps an Atik 314L OSC?!!

[Zakalwe]

Sorry to but into your thread again Andy.

I was on the verge of pressing the button on the 314L+, but have hmm'd and haw'd some more. The small sensor size on the 314L has put me off TBH, so I have ended up opting for the QHY8L OSC. It's a fair bit cheaper than the 314L, and I know that there is some small issues about amp glow, but I think that the bigger real estate will suit me better (I don't fancy having to mosaic for nebulae).

[AndyUK]

No worries Zak... I don't mind admitting that that image from Kevin made me dither again too, however, to add additional food for thought (also for Sara), have a look as the atik website with their 2011 competition gallery of 285 chip images - Category II

Hmm....

[Zakalwe]

No worries Zak... I don't mind admitting that that image from Kevin made me dither again too, however, to add additional food for thought (also for Sara), have a look as the atik website with their 2011 competition gallery of 285 chip images - Category II

Hmm....

No I'm not looking...I'm not even listening Lalalalalalalalala

I got fed up of thinking, and reading reviews, and pondering. and researching, and changing my mind, so I ended up making a snap (ish) decision after talking to Bern at Modern Astronomy.

[Deneb]

Buy the 314L Andy, you know you want to...

Nadeem.

[RobH]

I owned an Atik 16HR OSC for a while.

The idea was to use this for the colour data and then use the mono for luminance/NB etc.

I found that the lack of resolution and sensitivity meant that very quickly I decided that despite the faffing about with mono and filters (and there can be a lot), this was the way to go for the best results and sold the OSC.

Rob

[Beyond_Vision]

Fair enough Rob but with 6 mpixel you have room to loose some resolution

[Tim]

Andy, I have both, a QHY8 OSC and an SXV H9 mono with LRGB +Ha,Oiii, Sii filters and wheel.

On the few occasions per year when the nights are clear and with little moon, the OSC comes into its own, gathering enough data in a single session or two for a reasonable image. It is my camera of choice for star parties, and for my portable setup. Combined with a reasonably fast scope (f5-6) it does a nice job and no messing about with combining colours etc. I have to use mine with a LP filter (CLS) because of the local skies, but I use it even at dark sky locations. On a full moon night though, or greater than half moon, it really struggles, the background is just too light for a decent image. This is where the adaptability of the mono camera comes in, switching to NB filters at the blink of an eye. LRGB imaging is frustrating at times, and more complicated than narrowband imaging for instance.

Both cameras are in a way a compromise, but the mono camera will let you do everything that the osc can do as regards final results, and offers the advantage of narrowband for those moony nights.

If I had to choose just one, I'd go for the mono. But you would have to pry my OSC from my cold, dead fingers

HTH

Tim

[RobH]

Fair enough Rob but with 6 mpixel you have room to loose some resolution

True enough Kevin....and I keep looking longingly at the SXV MX25C on UKABS

I think that with a large sensitive sensor, OSC certainly has its benefits, but the smaller 285 OSC didn't wortk for me.

Your results speak for themselves of course

[ollypenrice]

Well, lots I agree with here. If I only had one it would be mono. I'm slightly surprized that no one else finds OSC quirky. Sometimes it is easier than LRGB, sometimes much harder in my experience. Maybe I'm doing something wrong!

I'd like a large format 11 meg chip but the filters are the killer. I could go for an OSC but this is what makes me nervous. On the left, OSC. On the right, Ha (from our mono camera) plus OSC. See what I mean?

Olly

[Zakalwe]

I'm right in thinking that you could use a OSC with narrowband filters? Yes you would loose all of the RGB pixels, but as BeyondVision has said, the QHY8 has 6 megapixels, so using 1/4 of them (probably less than that with the Bayer matrix?), you would still have more active pixels than a mono 314L?

Yes they pixels are less sensitive on an OSC camera, but it gives an option?

Or am I barking up completely the wrong tree?

[RobH]

On a mono camera with any filter, all of the pixels are receiving data.

With an OSC, in Ha for example, only 1 in 4 will be getting any data ( The bayer matrix is 1 red, 1 blue and 2 green)

It's not down to how big your chip is, but how many active pixels you have receiving light from what you are trying to image.

With NB, mono is the way....you can use OSC, but it's very inefficient.

[Zakalwe]

On a mono camera with any filter, all of the pixels are receiving data.

With an OSC, in Ha for example, only 1 in 4 will be getting any data ( The bayer matrix is 1 red, 1 blue and 2 green)

It's not down to how big your chip is, but how many active pixels you have receiving light from what you are trying to image.

With NB, mono is the way....you can use OSC, but it's very inefficient.

Thanks Rob.

So (for instance) the QHY8 with a 6 megapixel sensor would be using approx 1.5 mega pixels in narrowband, versus the 285 chipped CCDs which have also 1.5 megapixels?

Of course, the mono CCD will have more sensitive pixels.