Big Telescopes



Lord Rosse's 72 inch "Leviathan" at Birr Castle in Ireland
(image source)
  Sooner or later you are going to want a big telescope.  It's just a matter of time, if you stay with astronomy long enough.  The questions you need to answer before you buy are:  When should I buy, how much should I spend, and, what type and size of telescope is going to suit my particular needs? 

There are many things to consider, many you will not think of until after the fact without the help of some "been there-done that" experience.  In ten minutes, this article will give you the information you need to make a choice you will be happy with for many years.  You don't have to learn everything the hard way...

When To Buy

Most people start out with a smaller telescope for several valid reasons.  Cost is one big reason.  Portability and ease of use is also extremely important to a budding interest in astronomy.  But, after the astronomy interest has developed for a while, the idea of a bigger telescope begins to grow into a full fledged case of "aperture fever".  This is usually a good time to start looking at bigger scopes, and deciding what is right for you.

Having a big scope that takes a little more time and effort to lug around can kill a beginners interest in astronomy, therefore, I don't recommend it when buying a first telescope.  Once the hobby has developed though, a big telescope is a natural addition.  Key word, addition.  Don't sell your smaller scope to help pay for a large one.  Keep the small one for when you don't feel like messing with the big one.  This will happen more often than you think.

How Much Should You Spend?

Obviously, this can only be answered by you.  I can give you very good recommendations for different budgets, though.  Ultimately, you will have to figure out how much you can afford or save up for.  I'll give you my best advice below, so you can get the most for your money and the equipment you want.

Size and Type

These are the big questions.  I will assume that by now you have a good working knowledge of the types of telescopes that are available.  I will break down each type from the standpoint that we are talking about larger telescopes in the 8-16" range. I will give you a good idea of what each type is best suited for, what performance and features you can expect from each,  and what you can expect to pay, along with links to dealers I prefer.

1. Dobsonians:  Probably the most popular choice when moving up to a bigger telescope.

An 18 inch f/4.5 Dobsonian
(image source)

Pros:  Biggest aperture telescope available, reasonably portable even into the 16-24" range.  That's a lot of telescope.  Can be very portable in the 14" and under range.  Mass produced scopes in the 16" and under range are very reasonably priced with decent optical quality.  High end custom ordered versions have exquisite optics and craftmanship in the 14" and up sizes.

Cons:  Manual motion in the basic versions, although this is not a big concern to some at all.  Tracking and goto begins to raise the cost considerably.  Mass produced dobs use laminates that run the range of quality from good to inferior, use caution, read lots of reviews. 

I recommend:

$$$$- Webster Telescopes, Starmaster telescopes.  Webster has the cleanest design in my opinion, and easiest set up, my first choice.  Starmaster also makes exsquisite equipment, and would be the first choice of many others.  Both use only the finest optics, period.  Expect to spend $6,000 and up, way up.

$$- Orion 12" and 14" truss tube designs, Skywatcher 12", 10", and 8" collapsible designs.  These are very acceptable options for the budget minded who still want quality.  Orion's come plain, or in complete goto/tracking setups.  Skywatcher is a "you move it" telescope, at least in the U.S.  They have goto/tracking available in Europe and Canada, but I have seen a lot of poor reviews for the electronics in these models.  The Skywatcher scopes themselves get very high reviews, though.  Expect to spend $600 to $ 2,500.

2. Newtonian reflectors:   The classic Newtonion design on a German Equatorial style mount is almost a thing of the past in today's market.
 
Pros:  Focal ratios of f/7 and above are excellent for planetary work.  The longer focal length also provide sharper images with less coma at the edge of the field of view than fast focal ratios.  GEM's of high quality are a pleasure to use for visual work.  They set up quick with a rough polar alignment, move smoothly, and track well.  Slow motion controls (either manual or electric) make occasional adjustments to keep objects centered easy.  They can be completely manual, or goto, or anywhere in between depending on your selection and budget.

Cons:  They are less portable in 10" and larger models.  The mount on good telescopes is very heavy, and takes a little time and effort to break down into managable sections.  Good for permanent installations, or rolling in and out of the garage, not so good for taking out to a remote location for a few hours.

I recommend: 

$$  Orion still sells decent scopes on quality mountings, albiet in shorter focal lengths of f/6 and under.  Celestron and Meade have some versions you may like to check out, also in shorter focal lengths.  If you are wanting a true classic, you can obtain one by watching Cloudy Nights classifieds, they show up every so often in f/7 and longer focal lengths.  That about sums up my reccomendations for this catagory.  Cost will range from a low of around $700 for used equipment in good shape, to around $2,000 for new stuff in the 10 inch size. 

3. Refractors:

Big refractors are basically any refractor in the 6" or larger range.  Even a 5" refractor can be a pretty heavy setup, but optically it is still only 5 inches of aperture.  To get into 8" and larger refractors you are talking lots of money, custom made, or longer focal length permanently mounted options.  You will occasionally see one on Cloudy Nights.  Most people looking to satisfy their thirst for big aperture do not go this route.  It is just too hard to find, and or, too expensive.  Refractors of high quality are the most expensive design of telescope at any aperture.

4. SCT's:

Schmidt Cassegrain telescopes are another popular telescope that is available in the 16" and under range, although portability becomes an issue beyond the 10 inch aperture.  Other compound designs are available, such as the Maksutov design, although they are generally of smaller apertures of 7" or less.  Today's SCT's are either fork mounted, or GEM arrangements, both with complete goto electronics.  They are used for both visual and astrophotography applications.  If you think you will be venturing into astrophotography, this might kill two birds with one stone.  After very expensive, fast focal ratio, refractors, SCT's on heavy duty GEM's can be the next best choice for most astrophotography applications.  For strictly visual use, you can go with lighter, fork mounted options.

Pros:  9.25" to 16" of aperture available.  Very good to excellent optical quality.  Completely robotic.  More easily transported than big Newtonians, but still bulky and heavy components to be transporting to a dark site on a regular basis. 

Cons:  Expensive.  $3,000 and up.  SCT's larger than 10 inches have components that are too heavy for some to manage by themselves.  8"-10" scopes are managable for most people and provide decent aperture.  Image shift is an annoying problem with this design.  Can be mitigated with the use of a Crayford focuser purchased seperately, but this can be a problem when observing the zenith on fork mounted versions. 

I recommend: 

Both Meade and Celestron can fit the bill in this catagory.  You will want to carefully compare their respective product lines to see what might work best for your needs.  Celestron has shifted most of it's product line to GEM's (but not all).  Their best GEM's are intended for astrophotagraphy and are pretty pricey, and heavy.  Meade is still a traditionally fork mounted arangement, some of which are a bit lighter and easier to transport for visual use, even in the 12" size.  If you can hoist around 65 pounds and are a visual observer, a Meade 12" LX90 or a Celestron 11" CPC may fit the bill for you.

Congratulations!  You now know many of the pitfalls, pros, and cons, that most people learn the hard way.  Whatever you decide, take your time.  Consider your observing location and habits.  Go to a star party and look through different designs.  This can be a valuable experience that will keep you from kicking yourself later.  Take into account the physical limitations of your own strength, how big your car is, storage, everything you can think of.  With a little careful consideration, you can get exactly the right telescope for you.

Thanks for letting me help out!