Choice of telescope

Last Edited By Krjb Donovan
Last Updated: Mar 11, 2014 07:55 PM GMT

Question

I'm about to buy my first telescope (for general viewing). It seems that there are a number of reasonably priced 3.5cm Maksutov-Cassegrains on the market, but most of them seem to have altazimuth mounts. I have always thought that equatorial mounts were much better, but various aids have appeared since my telescope book was published and some of them claim that modern altazimuth mounts make following an image very easy. Is this true? Or should I insist on equatorial? Thanks

Answer

Hi Michael, In reality, there really is no such thing as an "excellent" general viewing....telescope. You always sacrifice something for something else. For instance, us that are into DSO's (deep sky objects like galaxies, nebulae, star clusters, etc) want as large a mirror (aperture) as possible with a short focal length to maximize the FOV (field of view). Others who are more into lunar/planetary details want a different type scope (generally a 4 or 5 inch refractor with a front multi-coated lense up front) and with a very long focal length for super-high magnification of a very small spot in the sky (the planet they are viewing). They care less about how big the FOV is. Then there are comet hunters that want still a different system, generally a very low power scope with an ultra-wide FOV, say a full 3 degrees, for successful comet hunting. Variable star observers don't require much of any of these, so they can get by very well with a standard 6 or 8 inch reflector telescope of just average focal length, generally f8 or f10 scope. Then there is the fellow who has a very small car, so for traveling around, he needs very portable equipment as his primary factor, so he'll purchase a Mak (like you are thinking of) or a Schmidt- Cassegrain...with a sacrifice of both focal length, and that 30% secondary mirror obstruction which drops contrast and amount of available incoming light (a horrible sacrifice on quality of image)....so he gets screwed all around, just for the convenience of what he wants,.... easy portability. Scopes are like airplanes....all airplanes fly but you don't send a bomber to do a fighter's job...scopes are exactly the same way. (Otherwise, all us amateurs would have the same type of scope, wouldn't we? But we don't...there are different scopes for different folks, depending on your main interest.)

As far as the mount, the only reason one wants equatorial mount is for photography (and that in itself is an advanced subject in itself). I have never owned a bulky, heavy equatorial mount..they are time consuming on set up, and a lot of extra work, just to have one motion track the sky. Ain't worth it, compared to the ease of the alt-azimuth mount...in fact, I prefer the Dobsonian mount, un-driven and no go-to equipment. I am not lazy. I am my own drive and my own "GO-TO"....saves a lot of money that way which you can then invest into a bigger mirror and bigger scope. Only reason one needs clock drive to stay on an object is if again, you are doing photography. As far as goto's, why not just spend 3-6 months and learn the night sky yourself....and save a pile of money. It really isn't that difficult; If you can learn and memorize say 4 adjoining counties....Hampshire, West Sussex, East Sussex, Kent...then you can also learn and memorize in the night sky Gemini, Cancer, Leo, and Virgo. They are simply fixed areas of the sky (since 1930). No more picturing men or animals, but simple area's which are easy to learn. There are about 40 Northern hemisphere area's or constellations, and that's it. Simple. All you need is a good map (good star chart)...just like a sailor... a dark sky location, and a red flashlight to maintain your night vision. Sailors of the seas need good charts, and so does a sailor of the stars. For further advice, punch on our club website at http://www.velocity.net/~bwhiting and read "Tom Whiting's Sound Advice for the Novice Observer" and read over what I have to say about the subject to a Newbie. It will (or may) help you get started into our great hobby on the....right footing. As it applies to the UK just as much as does for the USA. Plus, learning the night sky yourself is very rewarding activity.... and you'll never be the guy whose internal telescope computer goes out on him on a beautiful night at a star party, and he's out of luck because he never took the time to learn the night sky himself, but depended on his GOTO...happens more often than you think. Clear Skies, Tom Whiting Erie, PA USA

PS...yes, the newer alt-azimuth tracking equipment is just as good as an equatorial tracking device. But, do you really want to layout the money for that convenience, carry all those extra batteries to power it, all those motors and servers and wires to connect, then you got to take the time (away from observing) to calibrate it, align it, level it (not necessarily in that order)....sounds like a horrible price to pay when all you really have to do for visual observing is....move the scope a little to the west, every few minutes? So, it takes two motions, up a little and to the right...So what? To me, the electrical/mechanical clock drives ain't worth it. You aren't a lazy person,.... and put those extra "pounds" into a bigger mirror and better scope! Just give me a DOB mounted manual scope, and I'm doing just fine. That's what all 5 of my scopes are, manual DOB alt-az mounted. Even at my highest powers, I only nudge the scope every 30 seconds or so to keep the object in the eyepiece. Unless you plan on astrto-photography someday, but that's an advanced topic which I don't do...besides, who can beat the Hubble or the twin 10 meter Keck's on Hawaii? No one. Just download their pictures from the internet. That's my feelings on it. Tom

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