"JG" no.spam@me wrote in message ...

Suppose you're back to buying your first telescope (but without losing any
precious accumulated experience). Your budget is (very) tight but,
nevertheless, you drive to your favourite telescope store.
Side by side are the 2 most expensive models you can afford:

On a (very) tight budget, nothing beats a Dobsonian-mounted Newtonian
telescope.

-Newtonian F7, 130mm aperture x 900mm focal length

This one apparently has an uncorrected spherical mirror (cheaper to
produce), which at f/6.9 is pushing the boundaries of what is
optically acceptable. There's no doubt that the manufacturer wanted
to keep the telescope tube as short as possible so that it could be
mounted on an EQ2, but I think that it might still be too big for the
mount. If the 130mm f/5 Newtonian (which has a corrected parabolic
mirror) is available, then that would be a better telescope overall,
although it may cost a little more.

-Mak-Cass F13, 102mm aperture x 1300mm focal length

This one should work better on the EQ2, and it's also very portable,
but it is smaller and has a narrower potential field of view.

Which of these would you choose? And why?

Of the two, perhaps the second one, despite its smaller aperture (a
major concession). The first one just seems too marginal in every
way, but I've never used it, so this is theoretical.

By the way, I don't know what the situation is in Portugal, but in the
United States, the second telescope is much more expensive than the
first.

Please also take into consideration portability, assembly etc...

Neither is difficult to assemble, and both are small enough to carry
around while assembled, for home use. However, if I were you, I would
seriously consider a Dobsonian--this is the most cost-effective type
of telescope for visual astronomy, as well as the most stable, in
terms of vibration. Other types of mounts and telescopes are more of
a consideration for different uses or budgets.


- Robert Cook