Question by madhan: tips on buying telescopes/spotters for astro and terrestrial viewing?
Hi,
I am an amateur hobbyist photographer. I am looking to buy a spotter or a telescope that can let me see astronomical objects and as well as act as zoom scopes to see terrestrial objects. I went through couple of forums and figured out that refractor telescopes are suitable to see both astro n land...See this one

http://orders.ebay.in/ws/eBayISAPI.dll?ImportHubViewItem&itemid=290398143498

it claims view of 40 miles??! Is that even possible??!

and I am eyeing this

http://orders.ebay.in/ws/eBayISAPI.dll?ImportHubViewItem&itemid=330467662652

Now, my doubt is, will I be able to use these telescopes for astro images and as well as like binoculars??

Thanks for the help in advance :D

Best answer:

Answer by Me again
OK dude, here's the drill. The first one is a spotting scope. It is basically half a pair of binoculars. Some of them go up to around 60X magnification or more, while typical binoculars are in the 10X to 20X range. But the drawback for astronomy is that they don't have a very big objective lens (aperture). So they are not really good for deep space observation because they don't have a very big aperture, which is what you need for faint stars and planets. Spotting scopes are typically used for terrestrial daylight viewing, such as "spotting" for target practice, viewing wildlife, and other distant objects. Similar to what you would use binoculars for, only more powerful. It is easy to see 40 miles, or even more. The trick is how much you see at 40 miles, which is a function of magnification, lens quality, and atmospheric conditions.
The second one is an actual telescope. Note that it has a larger objective lens which gathers more light, and therefore allows you to see fainter objects.
Both of these units can be used for either terrestrial or astronomical viewing, but the spotting scope is more suited to terrestrial viewing and the telescope is more suited for astronomical viewing. Both can be used for imaging if you can figure out how to attach your camera to them. There are telescope adapters for many cameras. I use a piece of electrical tape to attach my camera to my telescope.
I have a reflector telescope, which is worthless for terrestrial viewing, which is why I am in the market for a spotting scope.
You are correct in saying that refractor telescopes are more suitable for terestrial viewing, for a couple of reasons. First, they don't invert the image you see, and second, they are not nearly as delicate as reflectors. Spotting scopes can be tossed in the trunk of your car and transported easily, whereas a telescope requires extreme care and some tedious setup before you can see much, and they are harder to transport because of their size and delicate nature.

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