Celestron c8 for small nebula and galaxy?

[Nova2000]

Hi

As my topic says, is the c8 f10/6.3 with reducer good for dso imaging? Especially small nebulas and galaxies? Such as ring. Owl. Dumbell etc. 

Raj,

 

[knobby]

I've seen some nice images with the 130pds which would be cheaper and lighter therefore easier to mount ...

But yes, it would be ok.

[Carl M]

Yes you can use a C8 for small planetary nebulas and smaller galaxies, but it also depends on how well you are mounted and how accurate your autoguiding (or lack of) is because of the longer focal length.

How are you planning on mounting it?

[Nova2000]

5 minutes ago, Carl M said:

Yes you can use a C8 for small planetary nebulas and smaller galaxies, but it also depends on how well you are mounted and how accurate your autoguiding (or lack of) is because of the longer focal length.

How are you planning on mounting it?

Neq6, or a avx

[CraigT82]

The extra fl would be great for galaxies and small PN, no point in reducing it as they should fit on your sensor at f10???

[Carl M]

Neq6 will be fine, my C9.25 is piggybacked with an ST80 on an older style EQ6 and still rock steady.

You then have the option to use guidescope or OAG if you choose to autoguide. Most people would swear by an OAG when guiding an SCT, but can initially be a bit fiddly with spacing and getting focus with both cameras.

I'd also recommend using the 12dstring FOV calculator or similar if you haven't already, you may find that some DSO's you want to image in the future won't fit fully in the frame (M42, M33, Andromeda etc..), even with the reducer. Other than that SCT's are great for the smaller objects.

[ollypenrice]

Your sig says 'new camera coming soon' and this matters because at longer focal lengths you can end up with an unrealistic pixel scale. It is this, rather than focal length per se, which determines the seeing/ guiding precision needed. With your 700D you'd be working at 0.44 arcsecs per picel which I think most people would agree to be totally out of range. You will never get either the seeing or the guiding to deliver that kind of resolution. If you reduce to F6.3 you'd still be at 0.71 arcsecs per pixel and this, too, would be pushing your luck for the same reasons. So quite honestly you could use a shorter focal length, get a wider field of view and precisely the same real  level of detail. If the new camera is a CCD with large pixels then the C8 starts to make sense. With reducer and Atik 4000, for instance, you'd be at a far more realistic 1.2 "PP. Or you could bin an 8300 chip 2X2 to get just iunder 1.8"PP. 

The thing is not to build a system which has no hope of working at its theoretical resolution. Where resolution becomes unworkable is much debated but I won't be trying to go much below 1"PP because I think it's a wild goose chase. You do see reasonable DSLR images from this size of SCT but I have never seen one which actually had more detail than you'd get from a shorter FL/wider FOV.

If you don't go for the Edge you will certainly need the reducer because it is also a flattener, though it's only a so-so performer and won't give geat stars to the edge even of quite small chips.

Olly