Celestron Schmidt-Cassegrain Telescope. Which one?

Question

I am getting a telescope for my hubby's birthday and he wants a good one. I definitely want the Celestron Schmidt Cassegrain, but I'm torn between two of them:

Either the 9.25 inch or the 11 inch. I want to spend less than $3000, and I know the 11 inch is a little bit heavier. We are brand new, never had a telescope, but we are totally into this and want the best one.

Any suggestions?

Thanks a bunch!

Answer 1

Hi Mel -

That's an interesting question. I have owned an 11 inch Celestron SCT for over 7 years and I absolutely love it. It is not terribly difficult to transport or to set up, once you get used to how it goes together. It takes me about 15 minutes to set up, and I'm a geezer! Now, the interesting part of your question: Are you looking at the CGE, CPC, or SGT version? This is kind of an important question.

The CGE is most similar to the one I have. It is probably also the most expensive. It is mounted on an equatorial mount that is rock solid. Even for the 11 inch, no individual component weighs more than about 40 lbm, so it's reasonably easy to assemble.

The CPC is a fork-mount configuration. It is also very solid, but the fork mount is attached to the tube, and together they probably weigh over 60 lbm for the 11 inch version. This makes for a precarious assembly when you are teetering with this huge, expensive instrument held high as you try not to drop anything in the dark.



The SGT / NGT series is mounted on a new, more slender mount that is lighter and less solid than the CGE version. As a result, the telescope may become shakey in a windy situation, especially if you attach larger accessories to it (and everyone does that eventually).

This is important, because the mount is a critical part of the telescope, and once you buy it, you are pretty much stuck with it. I would never recommend that someone buy an excellent scope and put it on an underrated mount.

Since you mentioned the figure $3000, I must assume that you are probably looking at the low end mount. If so and if you are budget limited, I would reconsider and go with the 9.25 inch version on the best mount you can get. Or, if you can afford it, spend a little more and go with the CGE-1100. You will not regret that purchase - decades later.

Remember that you can upgrade any scope later with better eyepieces. Over the years, I have added a few Nagler eyepieces that give me spectacular views. But you can't go back and get a new mount very easily.

In summary, I can highly recommend the 11 inch Celestron SCT - it's a beautiful instrument. I use it all the time for demos to classrooms, scout groups, etc. The views rival some observatory scopes I have seen. But if you buy a good scope, be sure and buy a good mount.  The scope can be thought of as three basic pieces: the tube, the mount, and the eyepiece. The eyepieces you can upgrade later, but the tube and the mount should be top-notch to assure years of satisfaction guaranteed - and I can testify to that part..

If your husband is knowledgeable in this, I would involve him in the decision. I do not mean to imply that you do not know enough to decide for yourself; it's just been my experience that telescopes are not good surprise gifts - they tend to be kind of specialized and geared toward the individual.

Good Luck and Happy Birthday / Clear Skies to you both.

Answer 2

When it comes to telescopes, the bigger the better.  Unless real world things get in the way, like budget, bigger costs more.  Bigger can be a drawback for things like storing it and transporting it, and yes heavier.

Celestron has been making this kind of scope for a long time, they have a good reputation, you should be happy with either, personally I would buy as big as I could afford.

Answer 3

The 11 inch has more light gathering capability and more resolution, but the 9.25 inch is lighter and will be stabler, since they come on the same mount.

These are good workhorse scopes, but your question is like asking "I want to buy the best car out there!" with no idea of where you will drive it, how you will drive it, or what you will carry in it.

I'd hold off and get binoculars and some star charts instead, and meet with local astronomers. Have you ever lifted one of these things? :-)

Later: it's not just weight. These things are weird shapes and can be a challenge to pick up if you've never done it before.

Answer 4

A 9.25 or 11 inch telescope is a big animal.  Have you actually used one already?  I suggest you to visit a local amateur astronomy club and "test-drive" one.  While such a big scope will yield excelent performance, it will also require a lot of commitment from your side.  Unless you are absolutely convinced that you are into the hobby, your initial enthusasm will wear out quickly, and you will end up with a $3000 paper-weight collecting dust.

The best scope is the one you use most.  Many amateur astronomers find it easier to manage (and enjoy) a smaller scope that can be put to work in 5 minutes for a quick "star fix" every night, instead of a big scope that requires 1/2 hour to set up, and major physical effort to transport from storage to a suitable observation point.   I have two scope (and had several other in the past) and concluded than anything bigger / heavier than 40 lb will have to wait until I set up a permanent observatory.  Anything bigger than that is just too much hassle to haul around the house every time I want to use it (regardless of the fact that a heavy scope is much more prone to damage due to innapropriate handling).

The scopes you mention are excellent equipment, and will make most amateur astronomers happy for life, but before you make such a major expenditure, I strongly recommend you to test and use one just to get the flavor of what it takes.  You may find it that it is too big and heavy, unless you can set up a permanent observatory.

Answer 5

I don't believe in beginner telescopes.  So get what you'll use. The SCTs are compact - and that's important for portability.  And, with a really good mount, SCTs can be excellent scopes for astrophotography.  I wasn't interested in astrophotography, and decided to go with the biggest Newtonian Reflector that fits in my car - the Orion xt10i - a 10 inch Dob with computer locator.  The SCT will track the sky, and that is convenient, as you get an object in your scope, and it stays there.  But my Dob sets up in 3 minutes including alignment.  No polar alignment is needed.  And, the xt10i is about $800.  $3000 might get you an 11", but to me, that seems like alot to pay for an additional inch.  Don't forget to budget for accessories.  Eyepieces, padded cases or boxes, filters.  My club is buying a single $600 eyepiece (for a $20k telescope).  You may be able to buy a larger SCT on the used market.  One of they guys at my club had spent two hundred hours making his tracking gears smoother, got excellent results - and sold it for half of new cost!  Deals like that happen.

Here are the 3 P's for picking a telescope.  Price, Performance, and Portability.  Price and portability can be show stoppers.  Price less so, since you may be able to wait until you have more cash. But a scope that doesn't fit in your car is stuck where ever it ends up.  That leaves performance.  For deep space, what you need is as much light gathering as possible.  In your budget, that points to a reflector.

The push-to computer also comes under the category of performance.  Before buying my scope, i joined a local astronomy club and borrowed each of their loaner scopes in turn.  One was a ten inch reflector.  I spent half an hour not finding a fairly bright galaxy in my back yard.  It was too dim for my sky conditions.  Then, i repeated this for another galaxy.  Spending an hour to not find two galaxies is not something that will sustain me in the hobby.  With a push-to computer, i can observe a dozen objects an hour.  In in very short time, i found that very few galaxies can be seen from my heavily light polluted back yard.  And, an oxygen 3 filter lets me see most nebulae.

Finanlly, you should never buy anything you haven't looked through.  So join a club.

I'm already a little jealous of your hubby.

Answer 6

I would suggest the smaller, 9.25 inch for portability.  With the savings had from not buying the larger of the two, you can get a couple of good eyepieces, accessories and maybe a camera.

Answer 7

It'll depend how you want to use it, and how important portability issues are for you.  One thing to consider is as scopes get larger and heavier, the effort to set them up and take them down might mean you'll use it less often.

Personally, having started out with an SCT, I don't recommend them as first scopes.

They have long F ratios, so you get relatively narrow fields of view, and the larger central obstruction reduces contrast.

They also tend to be pretty heavy.

If you want to get into imaging, it'll be easier with a shorter focal length scope because imaging at higher magnification puts more demand on the mount.  (tiny tracking errors are more obvious with more magnification)  Objects that are easy for beginners to image tend to be large, and might not fit on the chip of a reasonably priced camera if you have a long focal length scope.

I see you are planning to image - on this basis, you do want an equatorial mount.  I'd also make a point of looking at the Meade SN8.  The SN10 has a nice optical tube, but the LXD75 mount really isn't beefy enough to handle the larger tube for imaging.

For imaging, a great mount with a mediocre optical tube will out perform a great optical tube on a mediocre mount.

From your comment about wanting to see distance, I'm afraid perhaps you're thinking you need high power.  High power can be great for some objects, but with a good scope with decent aperture you can find enough interesting objects to keep you busy for a lifetime at 50-250 power.  

Light gathering ability is much more important than maximum magnification.

Visiting your local astronomical society, and/or attending some star parties is a great idea, and will give you a chance to observe with a variety of telescopes so you know what you think about how they perform.

How a scope looks is not nearly as important as how well it does what you want it to do.  

An SCT may be the right scope for you.  But before you spend your hard earned dollars,  you should really compare them to a couple of newtonians (including a dobsonian, and one that's equatorially mounted) and an apo refractor in the 4-5" range.  

After all, what we think of whatever scope you buy isn't nearly as important as what you think of it after you've used it.

The biggest mistake most people make when buying telescopes is they buy too soon.  

Take your time, and the scope you buy will be one you'll get many years of enjoyment from.