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Hey there! I'm Dave Hearn and I'm the Director of Kissimmee Park Observatory, and I've been
using all kinds of telescopes for over 30 years. In this "Extra" episode of Star Hopping,
we're going to take a break from our normal routine and start our exploration of how to
buy Telescopes for Beginners; kids or adults that are just getting started in astronomy
and learning the night sky. There's a lot to talk about so we'll do this in two videos.
Here in Part 1, we'll talk about the 3 variables you need to consider in selecting a telescope,
and next week in Part 2, we'll tell you where you can buy them, and how much you can expect
to pay. More about all this great stuff right after this - stay tuned.
Hey Hello Hi and welcome to Episode 7 of Star Hopping with Kissimmee Park Observatory! I'm
Dave Hearn, and I'm totally jazzed to be your host. So this is our first Star Hopping "Extra".
Occasionally we'll need to discuss some other interesting areas of amateur astronomy while
we wait for the stars to rise a bit. This is one of those times, since in the recent
episodes we've covered everything in the eastern sky until about the end of November. We'll
get back to our deep sky targeting techniques in a couple weeks.
So you want to pick out a telescope for a beginner amateur astronomer. Selecting the
proper telescope is really an important decision to make because a great first scope can really
kickstart a wonderful lifelong hobby. I get asked about this a lot because it can be a
complicated decision. But no worries - we've got you covered.
As we mentioned earlier, there are 3 main variables that you need to consider when buying
a telescope. These variables will drive the features you'll need to consider in selecting
a telescope that will fit your needs. So here they are: the Cost of the scope, the Size
of the scope, and the Type of the scope. Sounds pretty basic, right? These are all somewhat
intertwined and changing one variable can affect the other two as we'll see.
For most people, the first and foremost variable is probably Cost.
How much can you spend or are willing to spend for that first telescope? It's very possible
to get a good quality, entry level telescope for under $200. A small scope like this is
easy to transport and set up, easy to look through for even small kids, and can be tucked
away in a closet when it's not being used. This kind of purchase will allow you to look
at craters on the moon, and enjoy looking at the brighter planets, like Jupiter and
Saturn. But that's about it - you wouldn't be able to look at many deep sky objects,
or see too much detail. But for some people, the moon and planets are super exciting to
find and examine, and can be a great first scope if that's all you're interested in.
Raising the bar to spend $300 to $500 can get you a larger diameter scope (we'll explain
why that's important when we get to the "Size" variable). This price range will also get
you some extra eyepieces, which will let you examine objects in more detail, like zooming
in on a lunar crater, or looking at the Rings of Saturn or the Moons of Jupiter. Plus, a
larger scope will let you get into checking out some of the brighter star clusters and
nebulae.
Jumping up to the $1000 level really makes a difference. Now you can look at really serious
scopes that have either significantly larger size or have additional technology attached
to them, like Go To systems that automatically move to find targets in the sky - but more
about that a bit later. Now you're able to view the entire Messier list of objects, and
get started on the NGC list.
Above $1000, you get into serious amateur telescopes. As with any hobby, it is possible
to spend tens of thousands of dollars on astronomy equipment, and some of us crazies actually
do!
So the next variable to discuss is Size, meaning the aperture, or diameter of the telescope.
As I mentioned, the variable of Cost goes up proportionally as you increase telescope
size. As we astronomers say, "there is no substitute for photons", and more photons
of light are collected by a larger lens or mirror. The larger the aperture of the telescope,
the brighter and clearer are its images. And when you have more light, you can increase
magnification more.
There is an important thing to know about image magnification. I am sure you have seen
advertisements for little cheap 2 inch telescopes that claim "See the planets at 1000X!". Sure,
you can use special eyepieces to push a poor little telescope to that level of magnification,
but the image will be so dim and so blurry, that it will be impossible to see anything.
All telescopes, if they have quality optics that are aligned well, can usually be used
at about 50 power per inch, so for a 10 inch reflecting telescope, you could use a maximum
of 500 power. This is a huge amount of magnification. Using this level of magnification on the Moon
would let you see craters within craters within craters! But similarly, that little 2 inch
scope could only go up to about 100 power max and still give good images. So, the bigger,
the better, as far as viewable images go. That's basically the main determination of
image brightness in a telescope.
There is a sickness (air quotes) amongst amateur astronomers known as "aperture fever" which
drives us to build or buy larger and larger scopes, so we can see faint objects even better
than before. So Beware - it's easy to get caught up in this! I should know - the KPO
Reflector is an 18 inch scope that weighs 450 pounds. When I used to move it around
before I built the observatory, I had a dedicated trailer for it.
So as you can see, with a larger scope comes portability and storage issues. A 10 inch
Dobsonian telescope can also be pretty heavy, and you would have a big problem getting it
into a compact car. But the images you would see through it are bright, sharp, and clear.
So the last variable to discuss is Type, which means the optical design of the telescope,
and to some degree how the scope is mounted. There are three main types of optical designs
and three types of mounts, which can be used in various combinations. The different combinations
lend themselves to specific abilities and activities.
So first let's look at optical designs. The first and simplest is the basic Refractor
telescope, which has a lens or set of lenses at the front and the eyepiece at the rear.
Refractors of any real quality tend to be expensive, and because of the difficulty of
manufacturing quality lenses of significant size, tend to be smaller aperture, maxing
out at about 6" or so in the most expensive models. Less aperture means less light, but
refractors have much better image quality, so they produce very sharp images, and are
excellent for astrophotography. The sharpness tends to make up a bit for the dimmer images,
if that makes sense.
The second common optical design is the Reflector telescope, which uses a concave primary mirror
that collects light, and bounces it back to a smaller flat secondary mirror set at a 45
degree angle. The light then reflects out through the side of the telescope tube to
the eyepiece, which magnifies the image. The great advantage of Reflectors are that they
can be BIG, meaning the primary mirror can be large. Reflectors have a less expensive
design per inch, so you get a lot more *** for your buck. So, brighter images for less
money. Sounds perfect right? Sure, until you get aperture fever and you back starts to
hurt on mornings after an observing session.
So to combat this size issue, we go to the third optical configuration, a Compound design.
In this setup, the light comes in and bounces off a concave mirror, except that mirror has
a hole in it that we'll understand in a second. The light bounces to a second mirror that
is convex so it further focuses the light, and then it reflects the light back through
the hole we saw earlier, and then into an eyepiece. This is called a folded light path
design. Very often a large corrector lens is mounted at the front of the scope to correct
certain optical issues and seal the optical tube. This results in a much shorter tube,
but still allows the large aperture. These types of scopes are generally more expensive
that a plain reflector, but not so expensive as a quality refractor, and the tube lengths
are much smaller.
So that’s about all we’ll cover in this episode. Star tuned to see Part 2 here next
week. We'll continue to bring you these astronomy tutorials every week. They will be designed
to help you find deep sky objects that are up in the sky at the time we post them to
YouTube.
If you found this video useful, please consider Subscribing to our Channel down there, click
the Thumbs Up, and please share it out to your friends who like looking at stars. The
more the merrier! Also, as I just mentioned, please feel free to leave any question or
comment below, and we will be sure to respond quickly.
Also, please follow KPO on Facebook, where we post all of our astrophotos and keep everyone
informed about upcoming astronomical events. We'd love to hear from you to discuss all
this great stuff up in the sky.
All the links to these places including our website kpobservatory.org, can be found below
in the Episode Notes as well.
And finally, if you feel this video provides you value, and if you'd like to see more,
please consider supporting us on Patreon, where for a couple dollars per video, you
can support our efforts and let us make even more great astronomy tutorials like this one.
Well thanks again for watching, and we'll see you next time on Star Hopping with Kissimmee
Park Observatory.