Advice On A Telescope

[Suhit Gupta]

I am in the market for a telescope, in fact I will probably be picking one up this Friday and I am seriously considering getting the Celestron NX114GT (http://www.celestron.com/prod_pgs/tel/nx114gt.htm). It is 1000mm, f/9.0 and has a diameter of 114mm (4.5"). It can be computer controlled and I can buy an adapter that would help me connect it to my Canon 10D for fairly cheap. And most importantly, this $700+ camera is currently available for under $300.

I am a big astronomy nut but I know only a little bit more than a novice when it comes to telescopes for amateurs. This is going to be my first telescope. So do any of you have advice, recommendations or suggestions on this telescope, or others? The most important consideration is cost which needs to be as low as possible (i.e. about $300).

[foldedspace]

I'm partial to Meade, personally. If this is your first, you might want something a little cheaper and portable. The ETX series is portable, flexible and has lots of accessories.

http://www.meade.com/catalog/etx/etx_mak.html

[Suhit Gupta]

Meade looks good but they are all several hundred dollars more expensive than then equivalent Celestron.

I am also worried about two things -

1) Will the secondary mirror (in the Celestron) interfere significantly with how much light the promary mirror captures?

2) Since I will be hooking it up the a Canon 10D, will the tracking be thrown off due to the weight of the camera?

Suhit

[BugDude10]

BTW, Suhit, where are you finding this for under $300? (I'm thinking about a 'scope, too.)

[sylvangale]

Found a guide to picking a telescope:
http://www.scopereviews.com/begin.html

From the guide your telescope is....

2) The Newtonian Reflector, invented by Sir Isaac Newton, uses a
parabolic mirror at the end of a tube and focuses the light back at the
front of the tube, where the eyepiece sits, after being deflected by a
smaller secondary mirror in the light path.

Reflector advantages: Cheapest of the three designs (especially those
on Dobsonian mounts), more portable than refractors of similar aperture,
inherently color free (no chromatic aberration).

Reflector disadvantages: Secondary obstruction results in some loss
of contrast, still quite large compared with Schmidt-Cassegrains, can
require frequent collimation (alignment) of optics.

[sylvangale]

Giant binolculars are cool 8O

http://www.telescope.com/sdx/H3181.jsp

[Filip Norrgard]

BTW, Suhit, where are you finding this for under $300? (I'm thinking about a 'scope, too.)
I would like to know that too! 8O

Btw, will you use a Pocket PC to control that telescope Suhit? :D

[Suhit Gupta]

BTW, Suhit, where are you finding this for under $300? (I'm thinking about a 'scope, too.)
Oh man, I am going to totally regret telling people this because now I bet they are going to go out of stock (so people, please leave at least one for me) but I was going to get it from B&H Photo Video.

Suhit

[Suhit Gupta]

Btw, will you use a Pocket PC to control that telescope Suhit? :D
:) Actually it can be controlled with a PocketPC as far as I know, although one has to buy a fairly expesive adapter. I was planning to hook it up to my laptop and/or PC. It comes with a RS232-to-serial cable.

Suhit

[foldedspace]

Are you going to be doing a lot of long exposures? If so, then a Schmidt-Cassegrain seems to work better for that. But what if you were to get a CCD instead of a camera adapter? That would be very small in comparison. On a reflector with an equatorial type mount, I'm guessing it could handle the weight of a small camera. The biggest problem is it has to track very smoothly to get decent exposures.

[Bob12]

I've been out of town, so came a little late to this discussion. Just to add a bit . . .

I have a Meade ETX125 and adapters for a Pentax Spotmatic. What someone said about the weight of the 10D is a real issue - the guidance mechanisms need to be very solid to handle that much weight.

A Newtonian scope is a good scope for the money. Probably only a Dobsonian gives you more scope for a given amount of money.

The only problem I have with Newtonians is their size which can make transport and set up a bit cumbersone. At a meter long though, neither should be a problem for you.

As foldedspace says, the Schmidt Cassegrain or Schmidt Matsukov (?) models are generally more suite to long exposures, though you'll pay more money for them.

One more thing to be sure of for photography, make sure your mount is the three axis type. Sorry, I've forgotten which is which right now - one is called equatorial and the other is alt-azimuth. Whichever is the proper designation, you want the one that you semipermanently set the mount for your latitude. Then you adjust the tilt and pivot of the scope to find your desired object.

And above all, ENJOY!

[Suhit Gupta]

Well, I was initially set on the Celestron NX114GT, but after talking to the Celestron rep today for a long time (very knowledgeable and helpful) he increased by range to the Celestron NX130GT, C6N and the C150HD. He strongly recommend that I get the biggest aperture telescope I could afford.

He also laid to rest the issue about the weight of the camera as the counter-balances on the telescope can be adjusted quite easily.

However, since I live in NYC, light is a big problem and another representative I spoke to (from one of the resellers here in NYC) recommended I go with a small aperture telescope.

Finally, both said that I have to be careful when thinking about astrophotography as the Canon 10D will not be able to focus with most of these telescopes. So I would have to buy a Barlow lens and/or a 2" eyepiece to get a better focus. I am now leaning more towards the C150HD or the NX130GT. The C150HD has the advantage of having a 6" diameter and a f/7.0 and can do a 1000mm. So it may be the best option for me. The big drawback is that it is a manual telescope. The NX130GT has a 5" diameter and an f/5.0, but it can only do 650mm.

I guess the NX130GT is the front runner now. But I am now more confused than ever.

Suhit

[Bob12]

I'm not sure why they'd want you to buy a Barlow Lens other than to get your money. A Barlow lens is the telescope equivalent of a camera's teleconverter. It changes the magnification of the eypiece you are using. Albeit manually, as long as you have an optical thing to look through (eyepiece, camera viewfinder, whatever) you can focus the telescope. It just acts as a large, manual focus lens.

Also, when weight was mentioned, the balance issue is not the main consideration - although it is important. The concern with the weight of the 10D, and any counterbalancers necessary, is whether or not the guidance mechanisms and their motors are strong enough the move and hold the weight.

Check www.telescope.com (Orion Telescopes). They sell a variety of brands and types of telescopes and they can give you a lot of easy to understand information about what you need and don't need along with how to overcome some of the big city problems you'll face.