Choosing scope upgrade path

[riklaunim]

I can't decide about "long term" plans about my astro hardware. I have 150/750 Newtonian and I have two options:

- update the Newtonian

--- low profile focuser

--- extra rings for the tube (so it won't bend when something heavy is attached to the focuser)

--- coma corrector

- change the scope to 8" in a compact size like GSO RC 8"

I'm planning to buy ATik 314L or similar cam (with ICX285AL) targeting solar system imaging (DMK21), simple deep space imaging (ATIK), star analysing etc. with star analyser Newtonia advantage is low focal length = bigger field of view. RC has small FOV and still no focal reducers, but doesn't need all that extra stuff. Longer focal length also requires better tracking/guiding (the future).

Can you point me some good directions on those two (or maybe third option?)

[ollypenrice]

A 1.6 metre focal length on a 285 chip is going to be very limiting in terms of targets that will fit and very demanding of good guiding. The EQs can probably do it but not easily and not always. That would be my guess. (I have two here). You will absolutely need to autoguide and to autoguide well and your polar alignment will need to be very good. Personally I wouldn't see the 285 and 1.6 metes as bedfellows.

Alas the webcammng and deep sky simply need different scopes, one with a long focal length and one with a short. What about a small refractor mounted on an SCT or Mak. Use the Refractor to guide the webcamming cat and the cat to guide the deep sky shooting refractor? All aboard an EQ5 or 6.

There is no point that I can see in using an RC for the webcamming job because it delivers a wide, almost flat field. A webcam has a tiny chip which won't need the field - which is costing you a bomb in terms of central obstruction.

Olly

[riklaunim]

Yes, you are right about the focal length problem - I've did some 314L+ checks in CCD FOV calculator for the newtonian and the RC - which would need APS-size camera to get whole bigger DS objects.

Mak is an option (iOptron, or second hand Intes) but I'm concerned about cooling problems under slight temperature changes at night. Vixen open Klevcov-Cassagrain is an option but they start at 200mm and in comments they aren't better than the RC.

SCTs cool bit better, and they have various sizes, but still - cooling, mirror shift etc... this isn't easy

Mak 6" + X" ED/APO small refractor on top of it?

[SteveP]

Rik

Just to reinforce Olly's point, the GSO RC and 314L wouldn't provide a good match. The important parameter, the imagescale, would only be about 0.8 arcsex/pixel. Typically, in a well balanced combination, you'd be be looking at about 2arcsec/pix. You'd get away with 1.5 but as the value gets smaller, it puts much greater onus on both polar alignment and more importantly the tracking abilities of the mount. You're needing to keep a very small section of the sky on those little pixels. Whilst this obviously isn't impossible, it will creat some difficulties

You're doing the right thing though by planning the next steps. Too often do people buy kit only to find they're not well matched to their needs. Have a look at the 2nd hand equipment for sale!

HTH

Steve