Go Out:  Look Up!

A Guide to the Sky, Telescopes, and Telescope Programs

Which scope to buy? 

There is no easy answer to that.

My wife asked me once, "Why do you need so many telescopes?"  "Because they all do something different."  Each type has a different strength.

For a Library Program, I recommended the Orion XT6i Starblast, a computerized "table" dobsonian.  It's a good sturdy scope for beginners and it's portable. 

If you were to ask me the best scope for a beginner serious about astronomy looking for a capable high-value scope, I'd recommend an Orion XT8i Intelliscope.  It's big enough to see "faint fuzzies" (a.k.a. Deep Sky Objects) and able to handle the high magnifications you want for Jupiter and Saturn (the Starblast is a bit small for that). 

Mounts for Beginners

For beginners and casual observers I recommend a mount that can be pointed at an object immediately, without having to plug things in and use a hand controller.  Why?Because if you have to plug it in to use it, you're not going to use it very often.  Guests won't be able to just play with it. In fact, most advanced observers have at least one scope/mount they can use immediately.  This is their "Grab and Go" scope.  There is a saying: "Your best scope is the one you use the most."  So if you're new and looking to buy, realize that a GoTo scope requires power to point and an alignment process prior to it being able to Go To.  Non-motorized scopes allow immediate use and pointing.  Some have computer guidance, making them Push-To systems.  The computer tells you to where to push the scope. One great thing about computerized "Push-To" mounts, is that they work just fine without power.  You never HAVE TO use the computer, but it's there if you need it.

A C102 refractor on a Televue Panoramic mount.  No gears or knobs: just point it.

Mounts are Equatorial or Altitude-Azimuth (Alt-Az)

Observing with Equatorial mounts can be a little complicated; they're good for astrophotography.

Alt-Az mounts essentially have an up-down axius (Altitude) and a left-right axis (Azimuth).  They're easy to point.

Another division in non-motorized Alt-Az mounts is whether they have gearing for adjusting the pointing.  These "slow motion controls" are very useful at high power, but unless you have an expensive apochromatic, you won't be at high power.  Knobs and gears will also confuse your guests.  Explore Scientific's Twilight Mount retails at under $200 and has these controls.

Some mounts such as Televue's Panoramic and William Optics EZ Touch do not have the "slow motion controls".   You simply point the scope where you want.   They are very easy to use. Both are more expensive than the Twilight mentioned above.  Televue is something of a Cadillac brand; the Panoramic retails at almost $600.

Window Scopes

What's a Window Scope?  It's a scope that sits in that room in a house or apartment that has a view. 

Here's a good summary of How to Choose a Telescope.  I'm going to refine that to focus on Window Telescopes. 

So what characteristics of Window Scope differentiates it from a general-purpose astronomy telescope: it should fit into the room (proper size and appearance). it should be something that novice guests can use without much instruction (preferably, put an eye to the eyepiece and point). it should be suitable for daylight terrestrial use and nighttime astronomy use. "Pretty" is a plus, because it's in plain view. I'm going to make a restriction based on characteristics 1 and 2 above: the best Window Telescope is a refractor on Alt-Az tripod.  Reflectors can work nicely for terrestrial and astronomical viewing, but they don't fit into the room and they're not as intuitive for the beginner as the classic refractor look.  Catadioptic scopes are small and intuitive to use, but they do not provide the low magnification/wide field of view that a refractor does.

An additional restriction on a Window Scope is tube length.  There are some very nice, inexpensive telescopes that are excellent for terrestrial and nighttime use, but they are sometimes three feet long or longer.  Basically, a scope that long becomes a nuisance set up inside.   $300 is probably a minimum starting point for a good achromatic refractor on a lightweight alt-az mount.  An Orion 80 Short Tube refractor is nice, very wide field scope.  It will be limited in magnification, but terrestrial, lunar, and sky-scanning is wonderful with it.  Celestron offers a 90mm refractor scope on alt-az mount for under $300.  The focal length is about 2.5 times longer than the Orion 80, so it takes up a lot more room at the window. "Enhance Dispersion" 80mm refractors, start at around $500 and go up quickly.  Lunt Engineering has a nice 80mm ED refractor for $450. By comparison an equivalent apochromatic will start at about $1000 more.

The short tube provides wide views and allows you to push the tripod legs right up against the wall.

So if money is no object, the best-performing, short, daytime and night time refractor would be a "fast" apochromatic refractor.  They provide wide fields and have color-correcting lenses that can handle very high magnification (50x/inch of aperture).  They are the most versatile scopes, but are expensive.

A wide field "fast" (meaning it has a low focal length/aperture ratio, like in camera lenses) achromatic or "Enhanced Dispersion" (ED) refractor is what you should look for.  Achromatic refractors are the least expensive, but they do not handle high magnification well. Basically that means that you can't crank up the magnification on Jupiter and Saturn without colors tending to bleed together.  You will not be able to "split" as many double stars as an expensive refractor  The moon will be excellent as well as the fainter deep sky objects. Aperture helps.  I love my fast 120mm achromatic refractor with its fast f5 600mm focal length.  I cannot exceed 200x for Jupiter and Saturn, but everything else works nicely.  New, the Orion 120 is around $300.  Explore Scientific has an equivalent.  Explore Scientific has a 100mm with a dual-speed focuser for $399.

My wife recently told me that a mutual friend was looking for recommendations for a telescope for their new house.  Oh, he's going to want a high-quality window scope.  I'm used to providing recommendations for really tight budgets, so it's  nice opportunity to make some recommendations for some more robust and higher quality equipment.

The telescope recommendation will be essentially be based on what he wants to spend.  There are some really pretty (and very functional) ED and "APO" scopes in the $1000 range.  Pretty counts on an window scope.  Perhaps one of the prettiest is the Televue Renaissance, which is not only beautiful in brass, but it's highly respected for its optical excellence.

I do have a strong preference on mounts, though.  I like a balanced alt-az without slow motion controls.  By balanced, I mean that the Center of Gravity of the scope is in-line with the altitude axis of the mount.  Mounts where the scope sits on top of the mount generally require friction clutches to keep them from falling over the front or back of the mount.  They then pretty much require slow motion knobs. 

The Televue Panoramic and Gibraltar mounts have a saddle that the telescope sits on.  The scope and the alt axis become close to coincident.  They are intuitive and effortless to use.

Other mounts clamp the scope right at the alt axis. The Vixen Porta series utilities this design. It includes slow motion controls.  The Explore Scientific Twilight I series is similar. For larger and heavier telescopes, alt-az mounts are available.  The William Optics EZTouch shown to the right can handle a big 8" SCT scope.  Furthermore, it can also mount another scope on it's other side.  Properly balanced, fingertips are all it takes to point. Explore Scientific Twilight II is equivalent, although the EZ Touch can be computerized (I don't know if that's true with the Twilight II).

C8 on William Optics EZ Touch

I have two primary observing rigs. One is a big dobsonian.  The other is the setup to the right: an Orion 120 f5 (short tube) apochromatic refractor and a Celestron C8 SCT.  The refractor provides very wide views and the SCT provides the high power (color free). The mount has encoders which I attach to a WiFi device and use an iPad with SkySafari to navigate the sky.  It's a really nice setup.  The refractor/SCT combination covers the same wide field / high power spectrum that a premium apochromatic refractor would, but for less money.  And I can "change magnifications" simply by moving my head.

120ST and C8 on William Optics EZ Touch

I can also go with a single scope or replace the refractor with my hydrogen-alpha solar scope.  Putting a white-light solar filter on the C8, gives me filaments and flares on one side and great sunspot detail on the other.

Questions or comments? Email:Jeff Martin