Expert: Tom Whiting - 1/20/2009

Question
hello, Finally I'm getting my 1st telescope... I'm confused between celestron 114EQ which lens is about 4 inches and the eye peace is on the side, the tube actually short, but this one they recommanded. and another one which is longer and about 50 dollars more, but the lens is about 3 inches in diameter, and the eyepeace is staight on the tube.this is celestron 90EQ... so which do u recommend????
the staff in the shops told me both kinds gives the same quality in the image, but the only diffrence is that the 2nd one can have more thatn 2 lens...while the first only comes with 50x and 100x so would you help me please??? I read alot about it in the internet, but cant make up my mind yet!, I'll spend about 350$ on the 1st one


Answer
Hi Maryam,
So what do you plan on specializing in your observing?  Deep sky objects, lunar/planetary details, double/multiple stars, comet hunting, variable star observing, asteroids, nova and supernova hunting, etc. etc.
Do you realize by now, telescopes are like airplanes; all planes fly
but you don't send a bomber to do a fighter's job....telescopes are
exactly the same way. Don't buy a bomber if you want...a fighter.
(Don't buy a lunar/planetary scope if you want Deep sky objects...
or mainly do comet hunting observing....each scope maximizes a certain activity in viewing (otherwise, we'd all have the same type
scope wouldn't we? But, we don't...that's why there are different scopes for different folks!
DID YOU KNOW THAT ALREADY?

You do know that us astronomers use our lowest power, or next lowest
powered eyepiece over 90% of the time (to maximize the 3 things you
lose as you go up in power...light, detail, and field of view).
Most of the time it's better to maximize the 3 at the sacrifice of
the one, the magnification. Never buy a scope based on power because
we already know that the maximum Effective magnification is about
50 power per inch of aperture.
DID YOU KNOW THESE THINGS ALREADY?

How much knowledge do you have of the naked eye sky? Can you point with your finger to the Beehive star cluster (M-44 in Cancer), the
Andromeda Galaxy, the Lagoon Nebula in Sagittarius, the beautiful double Albireo (Beta Cygni) in Cygnus, the double open in Perseus, AND the planet Saturn?   All easy naked eye objects in the night sky.
If you can't point with your finger where they are that, how do you
expect to point a small field of view telescope toward them?
CAN YOU POINT YOUR FINGER TO THOSE OBJECTS JUST MENTIONED?

Which local astronomy club do you belong to, and how many times have
you gone out observing with the group, just for the practice and
knowledge gained?
YOU DO BELONG TO A CLUB, AND HAVE BEEN OUT OBSERVING WITH THE MORE
EXPERIENCED OBSERVERS, TO FIND WHAT KIND OF SCOPE THEY USE, HAVEN'T
YOU?

If you answered in the negative to even one of the CAPITALIZED
questions, then I'm afraid you're not ready just yet for a telescope.
(But if you answered in the affirmative, then I'd get the 4 inch
because a 4 inch brings in (4 squared - 3 squared all divided by 9)
or 77.8% more light than the 3 inch.
DID YOU KNOW THAT, AND KNOW HOW TO DO THAT?  (light gathering Area of lens or mirror goes as the square of the diameter).
If you answered in the negative, and are fairly new to astronomy,
then I highly suggest you punch on our club website and punch on
"Tom Whiting's Sound Advice for the Novice Astronomer" at
http://www.velocity.net/~bwhiting

Hope this strange explanation helps you,
Clear Skies,
Tom Whiting
Erie, PA

PS...most new observers make their "first scope" a pair of Walmart
or K-mart 10 x 50 binoculars for about $40-50...until they learn
and understand the hobby, before plunking down hundreds of dollars on
a scope they find later, is unsuitable for their needs. We also do
not recommend an equatorial mount for your first scope, we prefer
the standard alt-azimuth variety, better known as a Dobsonian mounted 6 or 8 inch reflector telescope, DOB mounted,  with over 200% more light gathering power than the 4 inch you are considering, for about the same amount of cash.
Because unless your planning photography (an advanced topic in astronomy by itself)...there is no need for a heavy equatorial mount
with counterweights. Also, most of the better scopes (Discovery, Orion, Antares) have to be mail-ordered. We don't recommend either
Meade or Celestron any more to our newest members as one company went public, the other went bankrupt, and was bought out by Tasco (which we affectionately called THEIR scopes, trash-co's.)
So just a heads-up for you there, so you don't go off on the wrong end.
Tom