Levelling the competition

Here's another dull one. But please, help me choose my first telescope.

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:

-Newtonian F7, 130mm aperture x 900mm focal length
-Mak-Cass F13, 102mm aperture x 1300mm focal length
Both "Skywhatcher" and both in EQ2 mount.

Which of these would you choose? And why?
Please also take into consideration portability, assembly etc...

Thanks

Neither. Take the money, buy a considerably larger set of optics and
build a much larger Dobsonian. Still portable. Much better light grasp
and if the optics are good, better resolution. The EQ mount that comes
with these little telescopes won't do you much good for extensive
astrophotography, so put the $$ into the optics.

IMHO

Bart F.

JG wrote:

Here's another dull one. But please, help me choose my first telescope.

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:

-Newtonian F7, 130mm aperture x 900mm focal length
-Mak-Cass F13, 102mm aperture x 1300mm focal length
Both "Skywhatcher" and both in EQ2 mount.

Which of these would you choose? And why?
Please also take into consideration portability, assembly etc...

Thanks

I, for one, would probably go with the 130mm, f7 Newt, assuming similar levels
of optical quality. Though it would be the bulkier of the two choices, the
main benefits that I see are the larger aperture, which will pull in more light
and provide increased resolving power, and the modestly shorter focal length,
giving a somewhat wider maximum field of view, and, I'd bet it would cool down
to ambient temperature more quickly than the MCT, though neither should be
particularly bad in that regard.

That said, the Newt would be, as I said, a somewhat bulkier package and would
require more "maintenance" in the form of collimation and (very) occasional
cleaning of the mirror, which would be relatively open to the elements, at
least during use.

So, in short, _any_ telescope brings with it certain trade-offs and neither of
those particular scopes would be a bad choice. For myself, though, I'd choose
the Newt over the MCT, though I'm sure I could be pretty happy with either.
Hope this helps.

Tonya

"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