Is 25x to 30x magnification through a lens based telescope be used for astronomical purposes??

6 Comments

1. faesson says:

   June 8, 2010 at 8:01 pm

   Galileo had less… have at it
2. injanier says:

   June 8, 2010 at 8:25 pm

   The Moon is interesting at any magnification. 30x is a bit low for planets. You should be able to just make out the rings of Saturn, and see the Galilean moons of Jupiter, but the planets themselves will just be tiny dots. That’s a good magnification for sweeping the Milky Way.
3. gn says:

   June 8, 2010 at 9:20 pm

   You are misunderstanding your source of information. 25 to 30x means, “25 to 30x per inch of aperture.” If you have a four inch telescope, the formula suggests your maximum usable magnification before everything goes fuzzy is around 120 magnification. For a 6 inch scope, the maximum advisable is around 180x, and for an 8 inch scope around 240x. (8×30). That’s the way the formula works.

   To look at planets you will want *at least* a four inch telescope and preferably six to eight inches. On a good night therefore you would use 180 to 240x magnification. So for what you want you’re basically in the market for a six to eight inch Newtonian (dob) telescope.

   Some very high quality telescopes on very steady nights can do more than that. On a bad night, some telescopes won’t even be able to do 15x magnification per inch, because the atmosphere is too unsteady.

   For the moon almost any telescope and any magnification is amazing. Most telescopes, even mediocre quality, will deliver 100x per inch on the moon because it is so bright and has so much contrast.

   For Saturn, the *minimum* magnification you need to see the rings is around 33x, not per inch, but 33x total magnification. But you will be very happy with the view in a six inch scope at 180x.

   So, what you quoted is the usual formua for “what is the maximum magnification I can use with this telescope?” The answer is you take the size of the mirror in inches and multiply by 30. So a small 3 inch refractor won’t delilver more than about 90x magnification–FORGET WHAT THE BOX SAYS! They always lie when they put the magnification on the box.

   So you see, you can get more *usable* magnification with a *larger* telescope (larger aperture, that is larger diameter).

   Hope that helps,

   GN