Beginner questions about first scope

[keepthebeercold (Sven)]

Hello everybody,

and thank you in advance for your kind words of wisdom.

It's the same story you've heard many times before - a quickly aging suburban dad of two has decided to reignite his interest in astronomy
and finds himself struggling to pick the right starter's scope.

I'm looking for a light, easy to transport, not too much maintenance allrounder with soft budget cap around 500$. Photography is of no interest at the moment.
Main usage scenarios would probably be: 70-80% backyard stargazing (I live in Sydney, roughly halfway between Chatswood and Gordon) mostly moon and planets, DSOs would be
a bonus. 10-20% travel to close-by darker pockets like Lane Cove national park, other darkish areas between Rosevile and Turramurra.
10% companion for camping adventures.
At the moment time is the least available resource I have so easy setup/transport are highest priority for. Also I've personally ruled out Dobsonian's.

Scopes I am considering and would love your input on:

90/102mm refractors (eg http://www.opticscentral.com.au/saxo...-telescope.htm, http://www.opticscentral.com.au/saxo...-telescope.htm ).
I like the idea of having 102mm, but but I've read bad things about about chromatic aberration F5 refractors and 102mm/F10 appear out of budget.
My question about refractors is: how much of a deal is F5 vs F10? In essence would you recommend a 102mm/F5 over a 90mm/F10 for a beginner?

130mm newtonians (eg http://www.opticscentral.com.au/saxo...telescope.html ). Aperture is king, they said.
What I'm not sure about: a/collimation - how often required, how tricky? b/ the mount: online wisdom seems to disagree on whether Alt-Az or EQ is better, but the
trend seems to be that Alt-Az is more newbie friendly.

102mm SCT (eg http://www.ozscopes.com.au/skywatche...telescope.html ). Same question about the mount again. Also - how much
cooldown time should I expect for a small SCT like the one linked? More than 1hour?

So - any strong opinions or "meh, not much difference either way"?

Thanks & Cheers,
Sven

[julianh72 (Julian)]

Oops - never mind!

[jenchris (Jennifer)]

Think 8 inch Dobsonian

[Atmos (Colin)]

I'd go with a dob too Alt Az is certainly a better way to go for visual purposes. Does not require any kind of alignment, plug and play as they say.

[Rick Parrott]

Definitely Dob!
My first scope was a 6" reflector with equatorial mount; Gondwana Telescopes recently crafted a beautiful Dob timber table-top mount for it and now it doesn't stay dusty in my garage (although the old mount does)!

[raymo]

With achromatic refractors it becomes harder to control CA as aperture increases, but
f ratio is kept the same; hence my 102mm f/5 has more CA than my 80mm
f/5 does, and a 120mm f/5 has more still. Its a matter of compromise
really, more aperture is undoubtedly better, and can be used satisfactorily
on objects that are not too bright, and you can reduce CA on brighter objects
by stopping the scope down to say 70 or 80mm. CA increases dramatically with magnification, so when using higher powers you can reduce CA by using for instance a 20mm + 2x barlow, rather than a 10mm, as the barlow
doubles the f ratio to 10.
F/10 refractors obviously show less CA, but it is by no means eliminated.
You have to go out to f/15 and beyond for it to become negligible.
I've run out of time, so somebody else can answer more of your questions.
raymo

[ZeroID (Brent)]

6"'-8"-10" DOB, Daylight come and I wanna go home ..

Ooops wrong song but yep, best bang for buck and ease of use is a DOB. Solid tube will stay aligned almost forever as long as you don't drop it and it isn't that hard to do or super critical for visual.

I've moved on to refractors for imaging ( although I'm about to shift back to reflectors ) and I still keep the 10" dob around for the best views.

There is always some good second hand deals on here and you'll get plenty of after sale support
Probably from everybody !!

[keepthebeercold (Sven)]

First of all thanks for the quick replies.

I am aware that "DOB" is the standard answer for first scope, but my impression (disclosure: never ran into a DOB in real life before) is that they are significantly less easy to transport (particularly the sizes > 6") than the scopes I've mentioned. And that would definitely be a deal breaker for me.
If I was sure that I only want to use it at home I'd probably get an 8" DOB, but I very dislike the idea of carrying a DOB around.

[rustigsmed (Russell)]

+1 for an 8" dob.

8" dobs are easy to transport. large dobs are a different story

[Atmos (Colin)]

Although you may struggle getting the base of an 8" into a sedan, you could fit a 16" Lightbridge Dob into the back of a hatchback no worries.

[janoskiss (Steve H)]

Even if you decide on one of the scopes you listed, the EQ2 mount is not worth the bother: especially with the 130mm Newtonian, it will be too wobbly at mid-high powers. The nicest scope of the three is probably the Maksutov. But it's a small scope (I used to have one) so it won't show you much detail on planets, and it also has a very long focal length and a 1.25" focusser, so it won't do deep sky widefield very well either. (It's great for wildlife photography and birdwatching. Best with an AZ mount or sturdy camera tripod.)

For your first astro scope, as others have said 8" Dobsonian is tough to beat. The views will be vastly better than from any of the scopes you've listed. I'd recommend the GSO over Synta (i.e. Skywatcher, Saxon) because it's better accessorised, but either would be very capable. As you seem to be in Sydney I'd recommend going to Bintel and buying from them. (Bintel branded products are GSO btw.)

I'd also recommend investing in a decent pair of binoculars: 8x40, 10x50 (depending on how steady you can hold them) or if you're young with good eyesight 7x50.

If you want more (trans)portability still then get one of the truss models (collapsible tube): http://astropetes.com.au/telescopes/...llapsible.html --- I disagree with Atmos on the 16" LB: a solid tube 8" is a lot more portable/transportable. But just go to a scope shop and check them out.

[Atmos (Colin)]

Oh don't get me wrong, I by no means meant that a 16" is transport friendly! Just getting the point across that even a large dob can be transported into a small vehicle

+1 for the 8". 16" are wonderful to use but not good as a first scope, a LOT more effort to set up.

[Bombardon (Eugene)]

I regularly move a 10" F5 dob in an IX35 SUV. Some friends even rebuild their rocker boxes making them more back friendly . I have timed this. My 10" is a 4 minute set-up and can reach deep sky and planets. Allow $$ for good eyepieces. Avoid equatorial time wasting

[keepthebeercold (Sven)]

Thanks again for the detailed opinions.

Look, you guys make me feel really bad. I can hear the clear unanimous vote for the DOB 8". And at the same time I absolutely know a DOB is not going to be my first scopes.
I fully understand that they give the best bang for buck. but I look at them (I've watched about half a dozen videos on youtube 6"-10") and I know it's too bulky for me - at least at the moment.

I'm really looking for a grab and go, not much more than backpack sized solution.

[Occulta (Chris)]

Sven

Get yourselves to the Macquarie University Astronomy open nite on Saturday May 14 to look at and through many telescopes of all sorts. Starts at 18:30 and finishes at 22:00 or there abouts. Building E7B and the rear carpark for telescope viewing.
Details can be found here

I will be there with my 10".

Well worth a visit

Chris

[barx1963 (Malcolm)]

Sven
Go to a star party or observing night and have a look at what the guys doing visual observing are using. The mix is usually 80% dobs of various sizes, 10-15% SCTs and the remainder a mix of other things.
There is a reason why dobs are preferred as a visual instrument, and you gave the one of the reasons - "aperture is king". Dobs simply give the best bang for the $$$. On top of that they are versatile, great on DSOs, good on planets. They are easy to use, easy to setup, transportable, robust.

My first scope was a 130mm newt on an EQ mount. My next was an 8" dob. The night I first used my dob i had seen more objects within an hour than I saw in 18 months with the 130mm!! You see more, they are easy to use, and when it comes to portability, I definitely preferred the dob to the 130mm.

I used to transport my 12" easily in my little Astra no issues. And the great thing about a dob (especially the smaller ones) if you want an object and it is behind a tree, you just take the tube off. move the mount, put the tube back and away you you go. If using an EQ or Go To mount, you have to redo polar aligning or star aligning ( can be a real PITA at 1am)

Anyway, it is your choice to eliminate dobs without having seen one, but I will bet New York against a brick that if you go any of the scopes you mention, in 6 months you will be either:
-offering that scope for sale
-asking for advice on which dob to buy!!

Cheers

Malcolm

[janoskiss (Steve H)]

Originally Posted by keepthebeercold

Look, you guys make me feel really bad. I can hear the clear unanimous vote for the DOB 8". ... I know it's too bulky for me - at least at the moment.

I'm really looking for a grab and go, not much more than backpack sized solution.

Then I'd recommend either an 80mm ED refractor (second hand will be in line with the cost of scopes in OP; there is at least one on IceTrade) or the 127mm Skywatcher/Saxon Maksutov and an AZ mount (no half capable EQ mount is going to be anything close to backpackable - unless you mean large travel-the-world tourist backpack; it'd also cost you a bit).

When it comes to refractors it's worth getting a smaller ED ("semi-apo") type over a larger achro.

[keepthebeercold (Sven)]

I think I'm actually getting more and more confused, oh my.

Just in case I rethink on the DOBs - would a 6" be considered fine or not big enough?

[janoskiss (Steve H)]

The 6" Dob is a nice scope, nothing really wrong with it. The focusser is a bit of a cheapie compared with 8" models and up (ditto finder). But it's a great all rounder; I was impressed with its performance on planets at a star party. But the only reason to get it over the 8" is cost. It's essentially the same size as the 8", except for the diameter of the tube (and mirror of course). And it's a little bit lighter. But otherwise it's no more portable than the 8".

PS. I'm referring to the 6" f/8 Dob and not the f/5 table top model. The table top model would be okay if you want something ultra-portable.

[Malcolm]

Get an 8" or 10" collapsible DOB. You wont be sorry. Have a look here: http://www.andrewscom.com.au/optical-telescopes