To The Moon Alice, and BEYOND!!!
November 23, 2009 6:15 PM   Subscribe

Any suggestions for a high powered telescope that is t-ring compatible (for DSLR) AND is tough and light enough for backpacking and camping? I'm thinking 40 lbs max.

I've been searching around but the terminology is so varied it's tough to nail down. I'm looking here at Oceanside Photo and Telescope, but I don't even know where to start. Schmidt-Cassegrain Telescopes? Corrected Dall-Kirkham (CDK) Telescopes?

Please hope me, and thanks in advance!

Happy stargazing!
posted by snsranch to Sports, Hobbies, & Recreation (8 answers total) 1 user marked this as a favorite
 
I forgot to add that I'm hoping to spend around $600, but willing to save up for something really tried and true.
posted by snsranch at 6:23 PM on November 23, 2009


I found the astronomycast podcast on telescopes to be invaluable in just getting a sense of what is which and what I should buy.

The relevant episode is here.
posted by merocet at 6:28 PM on November 23, 2009


This is basically an unanswerable question without this bit of information: what do you plan to image? Astrophotography on bright near objects (like the nearby planets and Earth's Moon) is a whole different ballgame than imaging deep-sky objects, and each case generally requires different equipment.

But in general, you've laid down two criteria that are absolute dealkillers for good astrophotography. You want light/portable, and you're only looking to spend about 600 bucks. You can get a great visual observing setup within those parameters, but astrophotography is a totally different thing, requiring a lot more money.

The thing here is that for astrophotography, you're going to have to spend more on the mount than the tripod, and your "light enough" criteria almost shoots you out of the water right there - because improving the stability of your mount is the single biggest thing you can do to take good images, and lightweight mounts/tripods are NOT stable. Ever. Under any circumstances. The best astroimager I know bolts his motor drive (to which his scope is attached) to a heavy steel pier set in concrete.

All that having been said, Orion is the best place on the Internet for both scope purchases and information.
posted by deadmessenger at 7:15 PM on November 23, 2009 [1 favorite]


Thank you mercet and deadmessenger! It looks like I'm overshooting my mark a bit. I will have to do some rethinking of my goals. This is excellent though. I'm here to learn so I really appreciate your comments and links!
posted by snsranch at 8:28 PM on November 23, 2009


If you're looking for "power" (magnification, eg "50x"), you're looking at very very much the wrong thing. What matters is aperture, because it's aperture that defines how much light you get in. That defines your sensitivity and therefore how long your exposures need to be.

Like deadmessenger says, $600 and lightweight are both bad constraints. If you have anything but the hugest field of view (like a 28mm lens on your DSLR), you need a tracking mount otherwise you'll just get star-trails. And that really needs a heavy tripod. The tracking mount and tripod together are more than your budget. Hell, the tripod alone can be that much - see anything sold by Gitzo.

Ignoring your constraints for a minute though and going for compactness, a reflex (reflector) telescope like a Schmidt-Cassegrain is about as compact as you get: they're very short for their focal length because the optical path is folded, plus they have a very large aperture for their weight because the imaging is mostly done with mirrors not lenses (large-diameter lenses are thick and heavy). A Maksutov is similarly compact but they have a thick, heavy glass front element.

Reflectors do have some drawbacks though, which you will need to research. And you need some extra optics, like a field-flattener, otherwise the image you record will not be focused across the whole plane of your sensor.

You need to crank the budget up by a factor of 5 at least for quality results, sorry.
posted by polyglot at 9:50 PM on November 23, 2009 [1 favorite]


For astrophotography, a cheap way to do it is to build a barn-door tracker (aka a Haig mount -- google will find lots of how-to pages) and a cheap used lens. I've had good results with a 100 mm f/2 lens (nominal aperture 50 mm). For deep-sky objects you'd want a longer focal length and as fast as you can afford. New, B&H carries a Bower 800 mm f/8 T-mount lens for about $250, or maybe you can find an old Nikkor AI or AI-S telephoto.
posted by phliar at 1:09 PM on November 24, 2009 [1 favorite]


Ah, you guys are great. This question should have been, "How do I get started in astrophotography?". You folks have done exactly that. Many thanks!
posted by snsranch at 4:30 PM on November 24, 2009


For future searchers of AskMe for astrophotography, astropix.com has a fantastic reference guide.

Thanks again guys, I'm well on my way!
posted by snsranch at 5:42 PM on November 25, 2009


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