Full Frame or APS-C ?

[Waylandscape]

Lots of good advice guys, thank you very much.

I'm seriously coming round to the idea of an Astrotrac because it would be a lot more portable for use on location, both here and abroad, especially not having to carry a heavy battery pack and laptop to guide the thing.

I may well go for a HEQ5 or 6 at some later stage if I decide to go for a scope but working with my existing kit seems to be a sensible idea for the moment.

I already have a clutch of good solid tripods from Manfrotto and some spare heads that I can utilise as well so it seems like a sensible road to explore.

I'll certainly post some work up when I get anything worth showing the only thing I've done so far with the 5D that might be of interest here is a star trail shot I took a while ago.

It does show the type of image that interests me but I'd like to do something a little less typical if you know what I mean.

Just being able to get a good tracked shot of the Milky Way in the background would be a good start.

[JamesF]

I think you need to be careful when comparing CCD resolution with DSLRs, in particular mono CCDs. If you use a mono CCD (let's say the Atik 428 for the sake of an example) then whilst the resolution is 1932x1452, you'll get that resolution in all of red, green and blue, so you combine three 2MP layers to create a 2MP image. Because of the colour matrix a 12MP camera will only actually be capturing 3MP of blue and red data and 6MP of green and then synthesizing the missing data from that. (If it doesn't then I've badly misunderstood how it works. Someone please correct me

If in processing you apply drizzle to the mono images then you'd end up with a much larger image than 2MP, perhaps even comparable to the 12MP image from the DSLR. I've never stopped to think about how drizzle might work when the data comes from a colour camera before. It's entirely possible that it won't work as well because the raw data isn't there to start with. I really can't say. It would be worth looking into.

I absolutely don't disagree that a DSLR and good quality lenses aren't a sensible approach in many cases. I think there's a lot to be said for it, it's well worth consideration and in fact intend to do more of it myself. I just don't think you can look at the headline figures for resolution and say "this DSLR has six times the number of pixels as this mono CCD therefore it will produce better raw material for prints".

James

[StuartJPP]

What James says above is correct. Mono CCD also allows binning which isn't really possible with colour.

However I'd hate to be halfway though getting a mono version of the image posted above and the clouds come in (which is almost a certainty these days)...I'd have to drive up there again the next time the weather cleared. At least I'd have something to show.

[Gina]

What James says above is correct. Mono CCD also allows binning which isn't really possible with colour.

However I'd hate to be halfway though getting a mono version of the image posted above and the clouds come in (which is almost a certainty these days)...I'd have to drive up there again the next time the weather cleared. At least I'd have something to show.

I use the LRGBLRGB type of sequencing with the filter wheel so that I always get something before the clouds come back. I can do this with the ED80 and Baader LRGB filters as the combination is parfocal so no refocussing is needed between images. The enormously higher sensitivity of the CCD camera means I can get a good set of data and resultant image in a much shorter time than I could with a DSLR. And yes, binning the colour 2x2 means I can reduce the RGB times by over 3 times for the same amount of image data.

[Waylandscape]

Thanks for the advice folks.

I think it has firmed up my thinking about the kind of images I am looking to get.

I've just beefed up my low light capabilities by upgrading to a 6D body which first tests show to be off the scale compared to the 5D.

I think I'll be looking for an Astrotrac or a SkyTracker next and working with the glass I already have in the bag.

Watch this space...