Expert: Tom Whiting - 6/4/2008

Question
QUESTION: I have bought a SkyQuest XT8. I bought the XT8 that came with the IntelliScope adapter and I was wondering what I would have to buy in order for the finder to work. (a motor and the keypad, or is there more?) Sorry if this did not make sense, I am pretty new to exploring the sky. Although, if you can help in Any way I would Greatly appreciate it.

Thank you for your time,
Andrew

ANSWER: Hi Andrew,
All your problems would be solved if you would have just followed my
recommendations on our club website, as to the proper way to
get into our great hobby of observational observing, at
http://www.velocity.net/~bwhiting
and punch on "Tom Whiting's Sound Advice for the Novice Observer".

In our hobby, equipment (scopes) come last, not first, so put
all the heavy duty electrical and computer equipment away for
6 months, and follow the advice on our webpage.
Equipment (except for binoculars and a good star chart) come
last because if you can't point your finger to the Andromeda Galaxy,
Saturn, the Lagoon Nebula, the Beehive cluster, all naked eye
objects, how are you going to point an instrument at them.  You
can't.  Furthermore, what are you going to specialize in...Deep
Sky Objects, lunar/planetary details, double stars, comet hunting,
variable stars, etc etc.  There is a telescope out there that
maximizes each of these activities (otherwise we would all have
the same type of scope...but we don't).
Scopes are like airplanes, all airplanes fly but you don't send
a bomber to do a fighter's job...telescopes are exactly the same
way, so you don't get a scope until you know what you want to
specialize in, and you will specialize eventually, as there is just
too much out there.  So check out the website above, and enter the
hobby and activity the correct way.
Clear Skies,
Tom Whiting
Erie, PA
USA

FOLLOW UP:
I actually have no idea what equipment you have, or have purchased.
I use no GOTO's, no computer, no clock driven scope...I'm my own
Goto and my own arm power, I use no electricity or computers on
a scope.  So your first task is to learn the naked-eye night sky, and
it's not that hard. If you can memorize Pennsylvania, Ohio, Indiana,
and Illinois on a map, 4 adjoining areas, then you can also learn
and memorize Gemini, Cancer, Leo, and Virgo..4 adjoining areas in
the night sky...there is no difference, as they are all areas for
identification purposes only. You probably know 100 phone numbers
and addresses, you can learn and memorize the number and location
of 109 Deep Sky Messier Objects, especially the 30 or so naked eye
ones.
If you don't follow this route, some night you'll be out under a
beautiful dark night sky with other astronomers, and your computer
and/or GOTO will go out on you, and there you'll be, totally lost....
under a beautiful sky, and have to pack it in and leave because you
became computer dependent (and lost out on half of the fun, the
HUNT itself) so you're out of luck...whereas we who know the night
sky, don't have to rely on a stupid computer or GOTO system.
For What it's worth,
Clear Skies,
Tom Whiting
Erie, PA
USA

---------- FOLLOW-UP ----------

QUESTION: Thanks for your help and I read the article you have provided. I have been observing the sky for a few months now and I can easily spot things such as Orion's belt, Saturn, Venus, Mars, Jupiter, Big Dipper(of course), and other things. I have been viewing those things and the things around it with the basic things that came with my XT8 and I just felt like I would like to be able to see more specific details of the planets.

But to get to the point, I was just wondering what I needed for the finder to work, I was not going to actually purchase it, just yet at least.

But to a better question now. Since I do not have any trouble finding Saturn and other planets, I am going to eventually buy a 3x Barlow Lens. I was just wondering how the measurements work. Does it go from inside the eyepiece to the other side? or does it go from outside of the eyepiece to the other side? From the inside of my eyepiece it is 1 and 1/8 and the Barlow Lens I was looking at is 1.25. If you can help me with this I would appreciate it...

Thanks,
Andrew

ANSWER: Hi again Andrew,
Yeah, like I said, you have to learn your constellations...you have
yet to mention that you even know one...of the 40 or so Northern
constellations in the sky.  (Orion's Belt is just an
asterism...group of stars, in this case 3, which are located in central Orion, and the Big Dipper is just an asterism of 7 of 57 naked eye stars in the constellation of Ursa Major.  Neither are a whole constellation (area of sky) by themselves, just asterisms.
You need to concentrate on the whole area, whole constellations. Get a good star chart like either Cambridge 2000.0 or Norton's star atlas
and reference handbook, join a local club, or join up with other
people interested in same hobby, and learn the night sky together.
It is impossible to buy a star chart that is TOO good...they cost
anywhere from $20-40 dollars, but then they are good and accurate
until 2050 before they need to be replaced (due to precession-
star atlases are updated every 50 years).

Finderscopes...purpose of a finderscope is to...amazingly...FIND
things.  (because the field of view is too small in the primary
optics so you spend too much time hunting with the main optics).
So a good finderscope finds things in the night sky for you, using
BOTH eyes. So that eliminates all right-angle finders....only use
a straight thru finderscope so you have one eye in the eyepiece
of the finderscope and the other viewing the sky itself, so you
know where you are looking (finding) things.  A right-angle finder
is an "oxy-moron".  The other purpose of a finderscope is to provide
positive control of the scope itself, in other words, you know
EXACTLY where the scope is pointed. The best device for this is a
Telrad, or reflex finder, the kind that have three red illuminated
rings that you look thru. When sighted in like a riflescope, now
you know EXACTLY what spot in the sky your scope is pointed to, giving you amazing positive control of exactly where the scope is pointed,just like a rifle...think of your scope as a rifle, if it's not pointing exactly where you want it, then what good is it?  None.
So it's best to have 2 devices on your scope, a visual finderscope
and a reflex, or telrad finderscope (They are about $40).
Oh, one other thing about visual finders, throw away any visual
finderscope that isn't at least 30 mm objective or bigger. Those little 15 or even 25 mm finders...can't find anything except the
very brightest of objects, which we can see naked-eye anyway.
Since the purpose of a finder is to "find" things, you need at least
an 8 x 50mm or better 9 x 60 mm mounted on your scope. Now you're good down to 9th or 10th magnitude deep sky objects and double stars.
Those 5 or 6 power 20, or 30 mm finderscopes are toys, and a piece of junk for the serious observer....besides, they don't find anything.  I know, because we've all been down the road.  I actually use 2 Telrads on my 30 inch portable, plus one visual 9 x 60 mm finderscope, all sighted in exactly, during set up, and I can get
on any object you can name off, in less than 10 seconds.  Well, guests at the telescope get very impatient quickly, so you, as the
astronomer, have to learn to get on stuff quickly with no lost time.
New Guests at the scope get impatient real fast!!

This is where experience and knowledge of the night sky comes in,
your speed at getting on what people request, whether it's M-13
(Great Globular in Hercules) or some obscure planetary nebula like
NGC 4361 in Corvus.  Once you learn your basic constellations, memorizing the various objects become easy, as they are always in
the same place, relative to the constellation stars.  So like the
person in a new town, once you've been to the grocery store or the
Post Office a few times, you don't need the atlas any more, you have
them memorized because they don't move relative to the other buildings. Deep Sky objects are exactly the same way...once you've been there to see them a few times, you automatically memorize their
positions, so you don't need the star atlas anymore for that particular object...just like the grocery store.

So you first have to know your Leo, Virgo, Lyra, Cygnus, Sagittarius,
Scorpius, Hercules, Corona Borealis, Bootes, etc. is first for your foundation, then it's easy memorizing where the different objects are at.  And there is only about 40 of them "states" in the sky. Picture area's, not men or animals...since 1930 contellations are all fixed areas. So when you hear an astronomer say, the head of Scorpius, the club of Orion,  or tail of Leo, he really means...the panhandle of Oklahoma, or the Upper Peninsula of Michigan or the chimney of Idaho...he is simply narrowing down the search area, not picturing an animal or a man.

Yes, a barlow lens first slips into the eyepiece holder, then the
selected eyepiece fits down into the barlow. Barlow lens comes with
a tightening screw to hold the eyepiece tightly, and your regular
screw on the eyepiece focuser holds the barlow.
But problem is, isn't your Orion XT 8 a focal ratio of something like
f5 or f6?  This is a deep sky object scope, not a lunar/planetary
scope.  For those items, the astronomer will select a 4 or 5 inch
refractor, with a high f-ratio (long focal length) for much higher
powers with the selected same eyepiece, highly magnifying a very
small area of sky.  True, you can observe planets (and you made an
excellent high quality selection of a telescope BTW, we recommend
Orion, Discovery, and Antares starter scopes now)...but like airplanes, you've got a Deep Sky scope and not a lunar/planetary
scope.  You get a wide FOV (field of view) with not as much magnification, so it's best performance is on DSO's, not planets.
Emphasizing my first point...scopes are like airplanes, so you're
sending a bomber to do a fighter's job.
Oh, one advantage you have; You can build what is called an aperture stop that will help you...cut a piece of 10 inch circular cardboard paper to cover your entire aperture, with a little 2 inch diameter hole off center, but not to the point of the light touching the edge of the mirror, and fit it in position on the top of the scope, making sure the spider vanes holding the secondary mirror do not interfere with the light path, or the secondary mirror.
You've just converted your Newtonian reflector f6 focal ratio, to a 2 inch f15 focal ratio... straight thru (no secondary or vane interference)....AAR (Almost a Refractor) telescope, improving resolution by about 200%!  So that's one advantage us guys have with
our large reflectors...we can go "smaller and better"...read that,
higher resolution, whereas a guy that purchased a 3" refractor, he CAN'T go bigger to an 8 inch...for the Deep Sky Objects.
The disadvantage, you can only use this off axis aperture stop on
only the brightest of objects to improve resolution.  So if your
goal with a barlow is to improve resolution of the planets, try the
cardboard aperture stop first as it's a lot cheaper to make.
Also, remember that you are still limited, with an 8 inch mirror,
to 400X; it's about 50 power per inch of aperture.  Above that, you
are getting what is called "empty magnification" that is, you are
magnifying the imperfections and air currents just as much as you
are magnifying the object, so it gets bigger, but fuzzier, in the
eyepiece. And that 50 power rule only applies to exquisitely ground
and figured optics (which Orion's are)..it does not apply to the
cheap, junky, "department store" scopes...their limiting magnification is much much less, because they are junk grinds to
begin with.  (That exquisite grind and figure, to a few millionth's
of an inch, on the optics, are what you pay for).

Your eyepiece barrel is 1.125 inch?  I never heard of that one....
there is the Japanese 0.965 inch eyepieces, there are standard
american of 1.25, and then there are 2.0 inch eyepieces. But I never
encountered eyepieces of 1.125. That must be a new thing on the
market.  Well, if that's an accurate figure, you'll have to find
a barlow that's 1.125 inch diameter which holds a 1.25 inch eyepiece.
Good luck...and re-check that diameter of the eyepiece holder on
the focuser...I thought all Orion scopes were inch and a quarter.
Doesn't your 1.25 eyepieces fit that hole?  My Orion catalog says
the XT 8 can handle either 1.25 or 2 inch eyepieces. I think you
miss-measured it...you can use the standard 1.25 barlow. If your
1.25 inch eyepieces fit, then that's the diameter of that hole!!

Put a telrad on that scope, eliminate the right angle of the right
angle finder, and then you'll have a pretty good scope...now all
you need is the knowledge of the night sky, which you should have
done first, but....that's the way it goes.
Clear Skies,
Tom Whiting
Erie PA

FOLLOW UP:
But no matter what you do, you can't change the scope itself...an
XT 8 is a deep sky scope, not a planetary scope.  So I would make
my first purchase a 35 or 40 mm eyepiece, and not a 3x barlow....
Do you know that us astronomers use our lowest power eyepiece 90%
of the time out observing!  Why? Because you lose three things going
up in magnification...light (the image is darker), detail (the image
just isn't as crisp as you go up in power) and very importantly,
less field of view (the area of sky is much smaller).  So most of
us would rather sacrifice one thing, magnification, to gain THREE
things.  Plus, with say a 40 mm eyepiece working at 30 power, you
can now fit all those large open clusters in the entire field of
view...the Pleiades, the Beehive in Cancer, IC 4665 in Ophiuchus,
the double open cluster in Perseus, the ET cluster in Cassiopeia,
there are hundreds of them. So since your scope didn't come with
a low power eyepiece (I believe you got a 25 and 10 mm), I would
make my first purchase a low power eyepiece of 35 or 40 mm, which
you'll find you'll use 90% of the time out observing.
Another thing about very high powers (on planets), you only get
maybe one or two nights a month where the atmosphere is steady enough
(say one arc-second resolution) to take advantage of very high
powers.  Most of the time, with the jet stream overhead, moisture
in the upper air, dust, temperature inversions, etc. we don't have better than 2 or 3 arc-second resolution (unless you live in Hawaii) to take advantage of very high powers. So go for a low power eyepiece first, then later worry about the higher powers.
Just a thought,
Clear Skies,
Tom Whiting
Erie, PA  


---------- FOLLOW-UP ----------

QUESTION: I would just like to say Thank you Very much for the time you have put into talking to me, I am going to save this link and do everything as you say I should. I do know the whole Orion Conselation, but I could point out Orions belt the fastest, and I know theres a Nebula right below the belt, so thats what I go off of. But as I said, Thanks again for everything and as 1 last question, does anything of which you have said Change because I live in Riverside Ca (where there is a TON of smog).

Your time has been much appreciated (once again)
Thank you,
Andrew

Answer
Hi Andrew,
Yes, here are 2 Riverside Clubs you can look into, to join, at
http://www.skyandtelescope.com/community/organizations/searchresults?clubType=47

I would go for the first one, the Riverside Astronomical Society.
Second, like other astronomers, you need to get into dark skies
occasionally, well away from Riverside, to really see the deep
sky objects at their best, so by joining a club, you can observe
at their dark sky location, somewhere well away from the towns.
No, nothing changes...you still want a low power (40 mm) eyepiece
first, because you'll use it 90% of the time. Riverside may have
a ton of smog, but it also has a ton of light pollution too, and
that's the killer of astronomy.
Clear Skies,
Tom