[g__day (Matthew)]

Next year if I save my pennies well I was considering buying an apo. I have this vision in my mind where a sturdy mount is bravely carrying two rigidly secured scopes, my 9.25” SCT and a 4” – 5” apo. My naïve thinking is this might suit a range of targets well, so with this in mind I’d thought I’d raise a few questions to reality check this dream.

So what I would in effect be doing is keep my SCT with its piggy backed 80mm refractor, but replace my 5” MAK with a 4” – 5” apo. This rig would probably be used to be 20% - 30% (max) visual versus 80% - 70% imaging. Auto-guiding could be off any of these three scopes whilst one of the remaining two takes a picture and the third is there if I want a glance to see what is happening (being careful not to knock things in the middle of an imaging run) or put a video CCD camera in it to do the same. Eventually late next year (budget permitting) or the year after I would replace my main imaging camera (Canon DSLR) with a auto-guiding S-BIG camera.

So them’s the plans and I live in light polluted Sydney suburbs.

Now I’d love to reality check this thinking. So far of all things I’ve snapped planetary nebulae have taken my fancy for the SCT. I haven’t ever taken an DSLR image from my Megrez 80mm. So I have a few questions.

How do I decide on aperture? Is the range 100mm to 130mm a sensible choice for what I’ve just described?

Do I want to opt for an apo where you can add an electronic focuser as a must have, nice to have, or not really needed?

Should I lean towards a general purpose quality apo or go for one that is more specific to imaging (e.g. the televue IS series)?

Should I eschew aperture and go for quality (would a 4” Televue be better for my desires than a 5” Williams Optics)?

Am I going to have horrible problems matching final imaging cameras to this very different range of SCT and apo? (meaning sorry its two not one S-BIG or FLI or whatever needed)?

I say I like planetary nebulae on the SCT but an apo is more wide field – your thinking is wrong and you haven’t taken into account… whatever

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I’d really appreciate people’s thoughts here because if I say allocate $3-$5K for an apo and say the same for a CCD – what are my best options given what I have already and where I am trying to head all this?

Many thanks,

Matthew