DSLR & SCT vs CCD & refractor

[sgazer]

hello all,

I'm after some opinions and advice please. I currently image with a 300d and C8 SCT, normally with a 0.63 focal reducer and get some nice results. The FOV with this setup is about 1 degree and the resolution about 1.13"/pixel.

For a while, I've been considering moving to cooled CCD imaging, but large sensor CCDs are expensive. Recently I've been thinking about getting a smaller CCD to use with my C80 refractor. As an example, an Atik 16HR will give about 51' FOV and 2.22"/pixel. Or with the reducer 1.3 deg FOV and 3.33"/pixel.

This latter option would seem to make more sense, it's a cooled CCD, decent FOV on the refractor and much more light weight than the C8 + 300d. The downside is the reduced resolution of 2.22"/pixel vs 1.13"/pixel.

I'd be interested to hear your general opinions on these options and also whether I'll lose anything with the reduced resolution or whether it's unlikely to be noticeable due to atmospheric conditions etc.

Many thanks

[Daz1969]

I will be interested to find out what people think on this one too as iam thinking of getting an Atik 16HR to use with my c8.

Can i ask you why you would choose to use it with your refractor and not your SCT?

Daz:icon_salut:

[sgazer]

Daz,

mainly for the extra FOV I would get with a shorter focal length compared to the refractor, but also ease of maintainance of the frac and lower weight.

ps. All, you probably noticed I've put some items up for sale already, so decision made really, but would still like to hear people's opinions....although now I'm expecting "Don't do it!!!"

[Daz1969]

Ah, I understand. Good luck with what ever you do.

Daz.

[sgazer]

not much to go off there ! So I've taken the plunge and gone for the very reasonably priced QHY6 to give me an introduction into narrowband imaging and still leave some money for narrowband filters.

For the budget ccds, it was a close call between the ATIK 16ic and the QHY6, but I went for the QHY6 for the slightly higher resolution, slightly smaller pixels (I'll be using with a short focal length refractor), USB2, Exview HAD sensor (good in IR) and lower price.

I have a Mintron CCD with a Sony Exview HAD sensor and with an integration time of only 2.5s it can 'see' very dim objects, so I'm looking forward to trying the QHY6 with 10 minutes exposures!

It should give me a FOV or 28x21' and a resolution/pixel of 2.23".

As the 300d has not sold, I'll still have that for nice wide fields of 2-3 degress with the C80 (optional FR), although it's still up for sale.

[riklaunim]

For very short focal lenghts you need quite small pixels like Atik 314E, Opticstar 142 or for very very small focal lengths, lenses Opticstar 335M. Small pixels are less sensitive but will give the resolution needed at low focal lengths - Opticstar CCD cameras for astronomy and science.

Mintron is a 12 bit A/D while Atiks, QHYs are 16-bit - they have more color depth but they need longer exposures than "fast" 8 and 12 bit cams working at lower quality (I've imaged two globular clusters with 8 bit DMK21 at 1-2 second exposures)

[sgazer]

thanks, I gave the 314E some thought too and the 320e, particularly for the smaller pixels and higher resolution, but they were another step up in price and I had to factor in filters etc too. I think with typical UK seeing factored in, the QHY6 pixel resolution will be good enough. It's about the same pixel resolution I get with the 300d on the C80 refractor and I can't see any pixellation with that, so fingers crossed.

[Whippy]

I've never used a DSLR so I couldn't comment but I wouldn't get so hung up on resolution IMO. I've used my Atik on various scopes from a ZS66 with a focal length of 388mm to an ED120 with a f/l of 900mm and never noticed nor given any real consideration to issues in relation to resolution. If I can, I'll try and use the scope I need to frame my intended target and go from there.

Good luck with the QHY6 though, I hope it serves you well.

Tony..