Refractor for Terrestrial and Astronomy!

[nsfx (Sin)]

Hi guys,

I am looking to get a beginner's telescope and my budget is not much, around the $300-$350 mark. I saw a Celestron NexStar 90GT for $330 at the shops. Will that suffice for some basic planetary viewing and terrestrial use? Thanks.

This is the one i am talking about.

http://static.bhphoto.com/images/ima...00_1170950.jpg

Please kindly advise. Thanks!

[Visionary (David)]

Hi,
Having displayed rare skill in dutifully buying the first thing I tripped over, my opportunity to learn from error has been stupendous. Hold onto your $300-$400 budget, keep your powder dry. Start scanning the Ice Classified and look for choice high end 2nd hand gear.
Look at it this way, if you buy a cheaply then you won't get any money when you decide to trade up. If you buy a quality brand and a quality product and you buy 2nd hand if you decide to off-load the scope you will sell it for sort of the same money you paid for it!
The other huge advantage in buying quality x quality you will derive tremendous pleasure from using the thing and just looking at the thing. Hold tight, save your coin and go large, buy that I mean good! Do be tempted by aperture keep on the refractor straight and narrow and you will hove boundless pleasure from day one.
Cheers
David

[dannat (Daniel)]

try & grab the astronomers without borders ED80 available in the US, it is shorter then the 90 & will show less false colour

[SkyWatch (Dean)]

Apparently Costco had them about a year ago for $A229...
In general the price seems good for a basic go-to scope. It is a traditional 90mm f10 doublet with I believe 10mm (90x) and 25 mm (36x) Kellner eyepieces. It is f10 to try to minimise false colour. The views should be reasonable, but with a narrow FOV. The eyepieces are very much the basic versions, and of a design that is well over 100 years old.
It is big enough for viewing brighter deep sky objects, like globular clusters (47 Tuc, Omega Centauri...), the Orion nebula, Eta Carina, etc. Should give reasonable views of Saturn and Jupiter at 90x. Great on the Moon, but with some colour fringing.
Terrestrial viewing should be OK, but again the FOV will be narrow; and back-to-front (you would need an erecting prism to get terrestrial views that are correctly oriented).
Not sure about how solid the mount is: I suspect it is a bit wobbly, especially if the legs are fully extended and you are viewing at 90x.
You could upgrade down the track with better eyepieces, but as David noted this scope will be a bit like a new car: value will drop at least 40% as soon as you take it out of the show-room...
With all those caveats, if all you are wanting is a basic scope for occasional views of bright DSO's and ships on the horizon then it should do the job better than a lot of others around that price- and go-to is a bonus.
If you want a scope that you will grow with as an astronomer you might be better off getting a 6", or better, an 8" dob; but these aren't much use for terrestrial viewing.

Good luck!

Dean

[acropolite (Phil)]

+ 1 for buying an 8 inch dob, forget an 80 or 90 mm scope, goto is no big deal. If you're prepared to wait you'll find an 8 inch dob within your budget. For terrestrial viewing buy a pair of 8x50 or 12x50 binoculars. (they will also be useable for Astronomy).

[nsfx (Sin)]

Thank you very much for the advise guys. The shop I was referring to is Costco in Melbourne. Seems a bit odd it is $100 more than what they were selling it for last year. I will have a browse through the used section and see what I can get!

[SkyWatch (Dean)]

Originally Posted by nsfx

Thank you very much for the advise guys. The shop I was referring to is Costco in Melbourne. Seems a bit odd it is $100 more than what they were selling it for last year. I will have a browse through the used section and see what I can get!

I understand they had some sort of deal with Celestron, and had a version specially made up for them. The $A hasn't done so well in the last year or so, so the price would have risen accordingly.

[brian nordstrom (As avatar)]

For your $300 you wont do any better for a beginners scope , pretty good all round telescope , eg. a complete observing unit , nothing else to buy ( until the up-grade bug bites LOL )

I really don't know what old mate Dean Is on about the 'Design being over 100 years old ' ,,,,,,
In telescope design old means nothing , mate the Newtonion reflector is over 450 years old .

But for nice modern , fairly good optics , good build and very good GOTO , a little bit basic but a very good intro into it this goto stuff it would be a great first telescope that will be good for terrestrial and starting in astronomy .

Brian.

[julianh72 (Julian)]

If you can get that for around $350, it's a pretty good buy - AG is asking for over $1,000 for a slightly enhanced version which adds Wi-Fi connectivity (and a rather garish "Cosmos" decal):
http://shop.australiangeographic.com...90gt-wifi.html
while Bintel is asking $600 on special (usually $700):
http://www.bintel.com.au/Telescopes/...oductview.aspx

[SkyWatch (Dean)]

Originally Posted by brian nordstrom

I really don't know what old mate Dean Is on about the 'Design being over 100 years old ' ,,,,,,
In telescope design old means nothing , mate the Newtonion reflector is over 450 years old .

I meant the Kellner design: in its case by "old" I was thinking (and should have said!) they have a very narrow fov vs more "modern" designs. They were originally designed with slow optics in mind, so should work well with this f10 scope. You rarely see Kellners today except as "intro" eyepieces with entry level scopes- although good quality ones can give great, narrow field views, and if they have good coatings the light through-put can be very good due to having only 3 glass elements...
An oldie but a goodie...

[brian nordstrom (As avatar)]

I hear you mate , they might have a smallish FOV ( but so do Orthoscopics ) but yes , as you say well made ones do perform surprisingly well , also this scope with a couple of those sweet GSO 'super views' will fix any short falls the Kelners bring for very little money , but really they are plenty good enough for any beginner .

Brian.

Originally Posted by SkyWatch

I meant the Kellner design: in its case by "old" I was thinking (and should have said!) they have a very narrow fov vs more "modern" designs. They were originally designed with slow optics in mind, so should work well with this f10 scope. You rarely see Kellners today except as "intro" eyepieces with entry level scopes- although good quality ones can give great, narrow field views, and if they have good coatings the light through-put can be very good due to having only 3 glass elements...
An oldie but a goodie...

[nsfx (Sin)]

Thank you very much for all the advise guys, I went ahead and got the Costco Telescope and I am pretty happy with it. I am looking for a 45 deg diagonal for terrestrial viewing, can anyone recommend one that is cheap and good?

I am a bit confused between 1.25" and 2" ones. Which one should I get?

Thanks!

[ZeroID (Brent)]

The 2" is for a larger diameter focusser, I don't think that will fit your scope hardware. Stick with the 1.25" for diags and EPs. The GSO Superview 15mm and 20mm EP's are both excellent value for money and a 2 x Barlow will give you a range of magnifications to play with.

Enjoy !!

[nsfx (Sin)]

Originally Posted by ZeroID

The 2" is for a larger diameter focusser, I don't think that will fit your scope hardware. Stick with the 1.25" for diags and EPs. The GSO Superview 15mm and 20mm EP's are both excellent value for money and a 2 x Barlow will give you a range of magnifications to play with.

Enjoy !!

Thanks ZeroID. I actually just bought a Celestron 8 24mm for around $90. Hope that is a good one! Will try and find a 2x Barlow as well.