Saturday, November 10, 2007

Your first telescope ...

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I frequently hear from people wanting to get a telescope as a Christmas or a birthday present for someone who is just getting interested in astronomy. Even if they want one, resist. The best advice of experts is don't start with a telescope.

Update: If you really want to start with a telescope you should read Avoiding the Christmas trash-Telescope Blues.

Most inexpensive telescopes are very poor instruments that will be difficult to use and lead to frustration. Poor quality eye pieces, useless finder scopes, terrible tripod mounts, and advertised high magnifications that are unusable. Terrence Dickinson, a respected astronomy author coined the term "Trash Scope Blues" for these disappointments.

Different types of telescopes suit different purposes, requiring the buyer to consider trade-offs. Leave these decisions until you're more certain of what you need.

So what to get your budding astronomer? A good pair of binoculars, and a beginners' book on astronomy!
  • Dickinson's, "Night Watch" (4th ed.) is a good beginners book that I recommend. It contains lots of useful information, including discussions of telescopes for when you're ready to move up.
  • Binoculars for astronomy need to be able to gather a lot of light, so 8x50's are better than 8x25's (the 8 is the magnification and the 50 is the diameter of the lens in mm). You may want to read Tips for Store-Testing Binoculars. A rule of thumb is that the second number should be 6 to 7 times the first, hence 7x50's or 8x50's are good for astronomy. Of course, the larger the optics the heavier the instrument. While I have an excellent pair of 11x70's, they are simply too big for children unless mounted on a tripod. Also, look for binoculars that can take a standard (camera) tripod adapter.
Another good thing, is a Planisphere or star wheel. In a future post about the astronomy badge, I'll include some do-it-yourself templates for a simple one.

And if you really want to investigate telescopes, there are three two specialty stores in the Toronto area: Khan's and Efston Science are located near Yorkdale. Kendrick's is located near Dundas and Keele. no longer selling telescopes but still make good accessories.

  1. For a great example of where binoculars are better, consider our look at Comet Holmes. Also, I missed opportunities to see two magnificent comets, Hyakutake and Hale-Bopp, in part because I had no telescope at the time and didn't consider binoculars.
  2. A useful chart on binocular size can be found here.
  3. If you're looking for a simple free starter planisphere, look here.
  4. If you are considering a telescope instead of binoculars you may want to read a good article about the different types of telescopes. It covers reflectors, refractors, and compound designs. I'd also suggest talking to serious amateur astronomers about the pros and cons of each. BTW. Binoculars are refractors.
Update and important CAVEAT: If you want to see the rings of Saturn then hand held binoculars will not cut it. You probably need at least 20x magnification and that means a telescope!

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