Help a newbie decide on 'scope

[rj1211]

I have retired early, know a bit about astronomy but little about telescopes. I live in rural Shropshire (UK) so have the advantage of reasonably dark skies.

I have fallen in love with the Celestron CPC 800 GPS XLT, having cast aside the Nexstar 8SE where I am not convinced about the single fork mount. However, in reading about 'scopes I am now confused and don't know whether a good Dobsonian (eg the Skyliner 300P Flextube Synscan GOTO) might be better. I know the optics on apos score well.

Reading and getting confused is great, but I'd like to get started. On a pension, I need to make a good buy. My interests are 1) simply gazing at stars; 2) wanting to see detail on Saturn and Jupiter (and the Moon!); 3) burning curiosity about DSOs.

Any advice?

[x6gas]

Ah well unfortunately two of the three things on your wish list are contradictory, at least a little.

If you want to see good detail on the planets you'll need both a large aperture and a long focal length. This will give you the magnification you need via the scope and will mean you won't have to resort to very short focal length eyepieces. It also means that the field of view will be small... which in turn means it won't be ideal for large DSOs...

The way around this is to get a long focal length scope - like the CPC 800 - and get a focal reducer to add to the set up for DSOs. However, bear in mind that the "faint fuzzies" won't resolve much detail visually unless you have a LOT of aperture to play with (and possibly not even then) and if you ever go down the astrophotography route for DSOs then aperture doesn't matter quite so much...

When I was looking for my first scope, people kept saying that it depended on whether I wanted something for visual observing (in which case the advice was pretty much unanimously go for a Dob) or for astrophotography. Trouble was I didn't know which I was going to be doing most at that time. I have actually been very happy with my compromise purchase (a Celestron C6N-GT) but since I have been bitten by the astrophotography bug and knowing what I know now I should probably have gone for an 80mm ED refractor on a good mount (HEQ5 or NEQ6) as then I would have had a good imaging mount and a scope that would be good for deep sky that I could have used as a guidescope later on. But hindsight is a wonderful thing!

Ian

[cyborg421]

I suggest before you buy anything you try and see some of the different types first and get an idea of the size.

I was convinced I was buying the CPC800 until I actually felt the weight of it and then I knew it was the wrong scope for me.

You don't say how old you are (I am 50) but it would probably safe to assume you are not getting any stronger. If you go for something too big you may well find it unmanageable in a short space of time. I have got the 10" SW Dob and the base is 20Kg and the OTA 15Kg. At the moment (and hopefully for a while yet!) it is manageable and portable and I use it as often as I can.

My mate has the 12" and when I saw it I knew I had made the right choice in not getting something too big.

A CPC800 might be the right choice if you can set it up and leave it out but you do not say whether it needs to be portable.

In the end "the best scope is one you use".

Hope that helps

Simon

[Moonshane]

for me if you are a visual observer, you need aperture. this is plain and simple; there's nothing beats it. OK planets are a little specialised and double stars also look better with a smaller exit pupil (generated via a slower focal ratio) but everything else looks better with aperture and even planets and doubles look better in larger aperture faster scopes when the seeing is good to excellent.

a 12" dob is quite a large beast and for your circumstances, with good skies maybe something a little smaller might be better - a 10" dob is substantially smaller.

you will still get good to excellent views of planets and moon with such a scope and if you can afford an auto version this will even track at higher powers which will be a boon.

if you can simply roll out the scope from a garage say, then perhaps a 12" will be doable too.

best bet if you can is attend an observation meeting at a local astro society and then get an idea of what you like and don't before you spend your cash.

I am a committed dobsonian fan and have two (a 16" f4 and a 6" f11). both give excellent views of planets but there's no comparison on fainter stuff.

[umadog]

"Ah well unfortunately two of the three things on your wish list are contradictory, at least a little. If you want to see good detail on the planets you'll need both a large aperture and a long focal length ... It also means that the field of view will be small... which in turn means it won't be ideal for large DSOs..."

This perhaps used to be true when short focal length eyepiece had tiny eye relief and Barlows weren't well thought of. Nowadays neither of those things are true and so a scope doesn't need long focal length to be good for planets. There are plenty of good short-focal length eyepieces with great eye-relief. I admit they're expensive, but they exist. Secondly, why not just Barlow? There are plenty of good Barlows out there now. The TV powermates are reputedly wonderful if you want to splash out. But cheaper ones can also work well.

Take an 8" f6 with a ~1200 mm focal length. Not a particularly long focal length scope. Put in a 4 mm Radian and you get 300x and 20 mm eye-relief. That's almost more power than you need. Alternatively, you can Barlow a good 10 mm eyepiece and have two very useful magnifications.

No reason why a short focal length scope can't be good on planets. A Dob at f/6 the secondary obstruction is bound to be well below 20% so its presence won't even be noticeable. Heck, I'm getting the best Jupiter views I've ever seen right now and I'm at f/4.

[sabana]

Why did you cast aside the Nexstar 8SE. This is IMO the best compromise. Aperture size. Portability. Short exposure astrophotography of planets like Jupiter/Saturn and the Moon. The single fork mount is not weak. Its built to take the weight and a bit more. If you are really concerned then drop down to the Nexstar 6SE. Hope you enjoy your retirement.

[umadog]

Can the 8SE be used 100% manually without without the drives? I seem to remember seeing one in a store once and the salesman told me this wasn't possible.