Oh boy - another what to buy/recommend thread

[chrissara]

Ah yes...well things have improved on the health front with the missus (and I thank all the members here, especially Gargoyle_Steve, for all their kind words and support - chemo does knock a person around awfully) and it is time to re-consider buying a telescope.

Given that I am unlikely given recent events to be able to spend long periods of time at night viewing the stars, I figured I may as well go back to obtaining a good quality scope, but under $1000.

As such I have narrowed it down to two options;
(a) a Dob; or
(b) a Goto telescope such as the lower ETX models, a Bushnell, Celestron etc.

If I lean towards point (b), I would be looking for the best bang for buck. Goto's by their very nature are pricey, and I would suggest compromises are made in the optics to cover the costs of the mechanics etc.

You comments would be greatly appeciated. My leanings are towards a Goto becuase of the size and portability. Yes I can get a 12" DOB for under $1000, but I have to seriously question my enthuasism in using it in the long term as opposed to a simple set-up and goto type scope.

NB I would be interested in second hand scopes as well.

[ving]

hi chrissara, glad to hear things are on the up. its scarey business for sure, i have a girl here at work going thru teh same thing.

give the situation, I'd go a dob just because there les involved in set up and packing up. :)

[rmcpb]

Chris,

Good news on the chemo, my sister is going through it at present and its not nice.

I would agreee with Dave on the dob and even suggest an 8" as its almost grab and go, easily moved, doesn't take too much space to store, grabs a good chunk of sky and, given the price, you won't feel as guilty if you don't get to use it for a while.

Hope all continues to improve :)

[janoskiss]

You don't have to buy a 12" Dob. They also make 8 or 10" ones these days. :D And they will be simpler to set up then goto scopes with much less aperture. An 8" Dob is a very capable, mobile, grab and go scope. Setup involves pulling it out and plonking it on the ground. Just about anything on a tripod will be more work to set up. (I used to own an ED80 on an EQ5 and it was a lot more work to pull out and set up than my 8" Dob.)

But it sounds to me that you really have your heart set on a goto scope. You'll probably need to spend a bit more. Under $1000 you'll be hard pressed to find anything with enough aperture that will goto to too many objects you can actually see in any detail. And those objects you can see well with the small aperture you could probably find easily without the goto anyway.

Dob + push-to object locator computer might be something to consider also.

[chrissara]

Hmm okay...so 8" or 10" DOB.

I suppose the spare change does give the ability for extra eyepieces.

[acropolite]

I hope the chemo works well in the long term Chris. Personally I would go for a 10 inch dob, if you need go to capability add an Argo Navis.

[janoskiss]

Almost?? Well yours maybe with all that lead behind the mirror. :) The 8" GSO or Skywatcher Dobs are grab and go. The GSO just needs two handles in the right places on the base ($5 from hardware store + 5 minutes to drill a few holes and attach handles). I have been meaning to make a video clip of mine being carried down the flight of stairs to the backyard to show just how mobile the 8" Dob is. It looks kind of big but its mostly air in the tube. :) You do need to attach those handles to the base though. (Not sure but the Skywatcher/Saxon might already be okay for picking up by the tensioner handles.)

[rmcpb]

Steve,

The only thing not grab and go is the cool down time but the fans help there :)

Chris,

The 8" at f6 is a snap to collimate and you are right that the extra change can be used on a couple of good eyepieces, barlow and cheshire eyepiece.

[gbeal]

Biggest dob you can handle, and if it is 10" then you have the sweet spot of portability over aperture.

[janoskiss]

Good point Rob. :)

[Gargoyle_Steve]

Hey Chris it's good to hear that things have improved somewhat
:thumbsup:

I hope we might still catch up for a night's viewing sometime..... if ever your headed this way get in touch, you know where to find Ron and myself.

In the meantime have you seen this thread?
http://www.iceinspace.com.au/forum/showthread.php?t=15699

Hotkey in Maryborough has a 10" dob for sale, good price, would make a great scope for you I think. Get in touch with him.

Best wishes for you all, and I really look forward to talking again soon,
Steve

[astro_nutt]

Hi there Chris..good to hear things are looking up...
An 8' dob is a nice size to cart around..and with the change you might want to invest in such luxuries like a right-angled finderscope..light pollution filter or even a decent viewing chair...but whatever you choose..as long as you're comfy and enjoying the sights..that's all that matters!
Cheers!

[chrissara]

Hi all and thanks for the replies!

I fear I might suffer from aperture fever!, and my concern is that in 8 months time I may be inclined to purchase a 16" DOB!!!

What is the limiting mag of a 8" DOB versus a 10" DOB? I recall my 12" DOB that Steve has was around 14.5 as a limiting mag, but can't seem to find the site for the specs? Edit: just did a quick google and it appears that a 10" DOB has a limiting mag of 14.5 (so I assume a 12" is around 17?)

If I go for a 10" (this seems to be my choice) is it worthwhile paying more and getting a Truss dob design e.g. Meade? If not, i.e. standard dob base etc, what extras should I get?

Further edit: Just saw this site: http://observers.org/tac.mailing.list/2005/Apr/0494.html
Is 10" therefore the best bang for buck - I was surprised to see little or no difference between the 12" and the 16"

Also which would be a better low maintenance scope - the Truss or the traditional design? By that the one which would require less collimation etc overall.

[janoskiss]

If you think you will get such a monster, then I'd say definitely go for 8" now, for max portability.


There is 0.5 mag difference between 8 and 10", another 0.4 between 12 and 10". Pay no attention to absolute limiting magnitude figures. These depend on how dark your skies and how good your eyes are - and how optimistic the manufacturer. Relative limiting magnitude diff between two scopes the 2 x log base 2.5 of the ratio of apertures, eg., a 10" will go 2 x log(10/8) / log(2.5) = 0.49 magnitude deeper than an 8".

But numbers are numbers. You have to go and see for yourself. And try look through something real big like a 20-25" Dob at some point. Observing with the ASV's 25" Obsession really put things in perspective for me, and the 10 vs 12" question became a no brainer. 10" loses little in light gathering and resolution compared to what it gains in mobility and portability.


My 10" Saxon Dob seems to hold collimation extremely well. It's done 500km in the back of a van after collimating, some of it out bush on rugged terrain, and by Cheshire there was no shift in collimation. The GSOs need tweaking more often (have inferior collimation and locking screws, and the springs are too weak esp on the 12"), and usually need a little adjustment after a trip in the car. I expect a truss dob like the LB (ie GSO) will need doing more often still.

[chrissara]

Okay thanks for the replies. I am now going to ask a somewhat controversial question - are all Dobs the same? By that, are there any differences between say an Andrews DOB, a Bintel DOB, Meade, Saxon, Skywatcher etc? I notice there is a price difference between the various models, with some being more expensive than others e.g. I see some 10" Dobs for $649-$749, but some are $950-$1200.

[Scorpius]

For my six penn'th. I recently got the skywatcher SW880 10" f5. I was very impressed in the "gain" over my home brew 8" It has a short tube and fits perfectly in the boot of my car. Prices vary, but watch the delivery price !!. Some of the cheaper priced ones have inflated delivery costs. May be OK in the East but over here in the West we are sitting ducks to be ripped off. NVT in Perth have Australia wide delivery for only $18.00 But the actual cost of the scope is in keeping with the RRP.

The only dislike about the SW880 is the massive 4" R&P focuser (Racked in -- to make up the focal length) which is about as good for a door stop than anything else. I modded mine to a 2 speed Crayford. Check my web for details.

As far as I understand Andrews and Bintel are GSO from Taiwan. Meade is Meade made in China under licence. Saxon and Skywatcher from same soup kitchen in mainland China.

The SW880 has either a US or Canadian Pyrex primary, which accounts for more bux. Pyrex is not normally required in AU but in Northern hemispheres with extreme temperature changes. In average zones in AU it runs nicely without fan cooling. But provision is provided to fit a small 12v computer fan on the mirror mount. A Crayford focuser can add a few bux as well. Some of the cheaper are older stock and have R&P focusers. Most come with a 25 and 12 or 10mm Plossl.

Today's thought... Man is much wiser after he has fallen from a tree.