[Hotdog (Anthony)]

Hi,

I understand that the usual suggestion for a beginner is the biggest Dobsonian that he/she can afford/store/transport, and I can understand why. Certainly in terms of all round bang for your buck it's hard to ignore the 8 or 10 inch GSO and Skywatcher Dobs at $450/$650 from Andrews, complete with (almost) everything you need to get started. But...

I live in a unit just 13 km from the Sydney CBD so observing from home means peering at light polluted skies from my balcony. The confined space doesn't seem suitable for a Dob, almost all of the sky would be inaccessible for one reason or another. A short tube Cassegrain configuration reflector or refractor mounted on a tripod just above railings height would fare much better in this regard and enable me to access most of the western half of the sky. That's still not great, but short of moving home that's the best I can do.

I'm sure there are people thinking that even trying to observe from such a terrible location is a waste of time, and I should just forget about my balcony, buy a Dob and take it somewhere more sensible when I want to observe. The thing is, I really don't want to buy a telescope that I have to take for a drive somewhere in order to use (at least, not until I already have another telescope for home use...) because if I do that it's going to end up being used for just a handful of nights a year. Something that I can use for a bit of casual stargazing from the comfort of my own home whenever I want is going to get a lot more use than something that requires an expedition.

Portability is still an important factor for me though, when I do get the opportunity I want to be able to take the telescope with me to better sites during weekends away, holidays, etc. This means it needs to be easy to fit into a (small) car, and if it can be made to fit within airline baggage limits (OTA as hand luggage, presumably) that'd be even better.

Given the light pollution at my home site I'm expecting to do more lunar and planetary observations than DSO stuff, so detail and contrast at high magnifications will be more important to me than wide field capabilities.

Because of all the above I've found myself looking longingly at 127/150 mm aperture Maksutov-Cassegrains, such as the Sky Watcher Black Diamond Mak or maybe the Bosma Omega MC. These seems to tick all my boxes:

1. Compact configuration compatible with balcony observing.
2. Long focal lengths suitable for high magnifications without requiring extremely short focal length eyepieces or high magnification Barlows.
3. Small central obstructions for good contrast and almost no chromatic aberration, all good for lunar/planetary views.
4. Compact size and reasonably low weight for their apertures, so fairly portable.
5. Reasonable aperture, small compared to most Dobs but bigger than all but the most extravagant refractors.

Of course all this works out quite a bit more expensive (and somewhat less versatile) than the standard beginner's Dob. It looks like $700-$800 for the OTA, and then of course I'd need a suitable mount too. I'm thinking alt-az for the sake of simplicity, but it'd need to be fairly heavy duty to support these 6-7kg telescopes, especially with high magnifications. Maybe an Skywatcher AZ4 or SkyTee, or a GSO/Bintel Sky View II, another $400 or so.

So, am I being foolish in considering a 150 mm Mak instead of a 250 mm Dob? Is there something else that would suit my situation better, for example a small ED refractor?