The Heretic's Guide to

Frequently Asked Questions
About Telescopes

last updated March 14, 2012
    Q: Where should I buy my telescope?
    So you've decided on a scope, and you're anxious to buy one. Where should you go?

    Any choice is basically a tradeoff between price and service. A better price often means less service- but not always. There are many stores that give you both great service and excellent prices. What follows are my personal experiences; your mileage may vary.

    First choice: Find a local dealer. Surprisingly, being in a large metropolitan area is no guarantee of finding a dealer- and being out in the sticks doesn't mean you won't find one. The entire Metropolitan Detroit area had one small reliable store- now closed. We still have a number of camera stores and hobby shops with a few scopes gathering dust. Avoid such stores.

    If you're like most amateur astronomers you'll end up doing a lot of mail order shopping. Here's a list of places I and others have had good experiences with. If a place is not listed, it may mean I've never dealt with them, or it may mean I have....

  1. The Findascope Amazon Store. I've set up a store at Amazon with a wide selection of books and a selection of telescopes and accessories, mostly from Orion, that I can recommend. Buying here helps support this site.
  2. Orion has a wide selection, and excellent customer service. This is a mail order company made up of real astronomy buffs who will provide service after the sale. I once called them with a question about the focus range of a compact Orion scope I'd purchased used. They told me other customers had had the same concern, so they made up a run of focus extension tubes and supplied them, for free, to all the purchasers- including those who bought theirs used, like me! Buying through this link also helps support this web site.
  3. Astronomics. Another outfit with good service, good stock and good prices. No complaints from me, or anyone I've ever talked to.
  4. Anacortes Telescope and Wild Bird A shop for astronomers and birdwatchers, and why not? My TeleVue Pronto is a popular scope with both groups. I've only made one purchase from them, but I was pleased by the very fast and helpful response I got when there was a minor problem with my order.
  5. I've been buying all my new photography gear from B&H for many years. Very reliable, with excellent prices. I wouldn't go to them for detailed advice on cameras or telescopes, but if you know what you're looking for, they can be a good source. Besides photo and video gear, they carry Celestron, Fujinon, JMI, Konus, Meade, Televiue and Vixen binos and telescopes.
  6. Company Seven. A highly rated supplier of premium scopes and accessories from Astro-Physics, Losmondy, Questar and others. Not the cheapest, but one of the most knowledgeable, and the only place to go for certain top end gear like Astro-Physics.
  7. JMI- Jim's Mobile Incorporated. A manufacturer of a number of unique products, including encoders, drive electronics, and large telescopes. While many dealers carry JMI products- sometimes discounting a bit off JMI list prices- you can also buy direct from JMI. They are very customer oriented, and if you have a question you'll typically find yourself talking to the person who designed or built the product you bought.
  8. Land Sea and Sky - a good source for Takahashi binos and scopes.
  9. Lumicon. Great and unique supplies for astrophotography, unique photo and visual filters, good advice, nice people.
  10. Surplus Shed. This is a marvelous source of all sorts of gizmos with the emphasis on optics. They carry a nice variety of inexpensive, quality telescope and microscope eyepieces, including the Paul Rini eyepiecesi, and have more recently been developiung a wider range of new optics under the Wollansak brand. Wandering their website is a great pleasure- you never know what kind of finds lurk there. As I type this They've got a nice collection of focusers and objectives you could use to make your own telescopes cheaply. A favorite place to shop and just look around and a treasure trove for the ATM.
  11. University Optics. A small supplier of eyepieces and accessories, binoculars, and some telescope making supplies. Good prices, good service, honest advice and a few products you won't find elsewhere.
  12. BigBinoculars.com  was recommended by Howard Cohen as a supplier who took time to answer his questions and work with him. I haven't dealt with them personally. They carry a number of name brands, including Fuji, as well as their house brand "Oberwerk" Chinese made binoculars. I will admit to being put off by their giving a German-sounding name to Chinese-made optics- it smacks of being misleading-  but they do cheerfully admit that the scopes in question are from Chinese plants. I'd like to hear from someone who has tried these scopes and compared them with Japanese and German optics.
     
Where Not To Buy:
Department Stores
TV "Home Shopping" Shows
Any place that offers deep discounts, but can't answer your questions thoughtfully.
Any place for whom telescopes are not a major product line
Any place where the people selling the telescopes don't actually use them
Any place where you're treated poorly, or rushed to make a purchase.
What does "F/ratio" mean? Is an f/10 scope better than an f/6.3 scope?

A Few Words on Focal Length and Focal Ratio (f/ratio)

Many people are confused by these terms. Focal length is, very simply, the distance behind the lens (or in front of the mirror) where a focused image is formed. That spot is called the focal plane. Have you ever focused the sun's rays with a magnifying glass to burn paper? If so, you the distance between the lens and the paper where the image was brightest and smallest (and hottest!) was the focal length of that magnifying glass. By moving the lens back and forth, closer to and farther from the paper, you were trying to find the focal length of the magnifying glass.

If you have a lens with a 900mm focal length, and you point it at the moon, an image will be formed 900mm behind the lens. That means you can mount a camera so the film is 900mm behind the lens.

Eyepieces have a focal length too. To use an eyepiece with a telescope, the eyepiece is mounted so that the focal planes of the telescope and the eyepiece are in the same location.

Focal ratio, or f/ratio, is the focal length of a lens or optical system divided by its diameter. A telescope with a lensor mirror `that's 90mm in diamter and has a 900mm focal length has an f/ratio of f/10. But what does this mean?

F/ratio isn't a measure of quality. There are good f/15 scopes and good f/3.3 scopes. Varying the f/ratio allows designers to trade off different scope characteristics. For example, for a given design, the lower the f/ratio, the smaller the scope. But at the same time, the longer the scope, the easier it is to achieve good optical performance. This is increasingly important as magnification increases.

Most binoculars use very short focal length objective lenses- around f3.3. This is no problem on a 7x or 10x instrument, but if you tried to use those lenses to get 50x you'd see a lot of color fringing and distortion. It is possible, however, to achieve good color correction and low distortion in a very short focal length scope; it just takes more lenses (and more money). There are a number of excellent f/5 refractors that use multiple elements.

Most observatory instruments built these days have exceedingly small f/ratios, on the order of /1.2 or less, which is to say they're very short for their diameter. This is called "trading glass for steel". When you're making a telescope mirror that's 8 meters in diameter, every additional meter of focal length means more steel and concrete. These scopes use a lot of additional optics to correct for various optical aberrations. The cost of the additional optics is far less than the cost of making a bigger mounting and building.

In general, for a given optical design, the following rules generally hold:

Shorter  focal length:

Lower magnification (for a given eyepiece)
Lower contrast
Wider angle of view
Poorer color correction
Easier to mount
Less vibration sensitive
More abberations and distorion
Longer focal length (higher f/ratio):
Higher magnification
Higher contrast
Larger mounts needed
More vibration sensitive
Better color correction
Fewer abberations and less distortion
It's important to compare similar types. A 6" f/5 multi-element apochromatic refractor will have far better color correction and image quality than will a 6" f/12 achromatic refractor.



Q: What's better- a reflector or a refractor?
 

    About Different Telescope Types
Any type of telescope- reflector, refractor, Maksutov, Cassgrain, Schmidt, Yolo, etc.- can perform well if constructed well. While different types have different characteristics, any design can perform excellently.

Often you'll hear or read the opinion that "refractors have better contrast and resolution than reflectors", but that's simply not true. A well made reflector can have contrast as good as any refractor. The problem is that there are a lot of indifferent reflectors out there. If you've ever looked through a reflector with a mirror that really is accurate to 1/4 wave, you will be amazed at the contrast and sharpness.

Now there are real differences between types of scopes that make certain kinds better than others for certain applications, but for a beginner's scope in the under-$1,000 range they're really not important considerations. For more details on this, see Jay Freeman's page.  He has a nice summary of the characteristics of different kinds of scopes.

Q: What's a good scope for a child?
Well, it depends very much on the child.

First, consider that very few under-5s can focus a scope; many can't even view through a scope. For the youngest children stick with visual observation. And before giving a child a scope, ask yourself if the child is old or mature enough to take care of it. A child may mean well but simply not understand what's needed in taking care of a scope.

For most kids, a small dobsonian makes a lot of sense. It's rugged, easy to point, and won't try a child's patience. Mom or Dad will have to adjust the columation occasionally. A 4.5" dob kit from Stargazer Steve makes a nice parent-child project, and the child can decorate the tube and personalize it. An inexpensive alternative is under-$50 scope from Celestron mention on the first page of this site.

Q: Are those little refractors really better than a bigger scope??
I'll let correspondant Ron Smith answer this one. Ron writes::

I wrote to you some time back, perhaps 18 months ago asking for your help in  deciding which SCT to buy.  8" or 10".  f10 or f6.3.  Blah, blah, blah...  I  started by looking at an 8", worked up to a  10" and finally came back to the 7" Meade MAK LX-200.  You e-mailed back a short but very disappointing  response.   I mean, after all, I had done my homework and KNEW in my heart  that the 7" MAK was the answer. To paraphrase, you said something like, "If  you're gonna spend $3,500 to $4,500 why not look at one of the 4"  refractors?"  What nerve I thought.  What arrogance or perhaps even ignorance, I thought.  Why everyone who knows anything knows that aperture is  everything.  The puny 7" is a compromise for me to begin with.  After all, I  had my 13.1" light bucket and had the sky by the tail.  (I had a 3" Gibson  f10 reflector back in High School circa 1963 and I remember what Mars,  Jupiter and Saturn looked like at 475X through a 3")  A 4" for how much???

As good, no make that great, fortune would have it I bumped into a parent at  my kids school who had just "upgraded"  from a 14" SCT to a used 4" Takahashi FS102.  Wait a minute...  Upgrade???  The wheels spun and the brain tried to regroup.

Fast forward 6 months.

My Takahashi arrived.  Before it even left the packing materials behind, I  knew I was to be in for a major treat.

Fast forward 11 days.  New "astro-purchase-curse-fog bank" lifts.  Clear  steady dark sky.  Oh my God!

Today, 4 months post arrival. My Tak FS102 sits atop a Vixen GP/DX with Sky  Sensor 2000.  I have seen more "M" objects, detail on planets and  NGC  objects than in all my the previous years as an observer.  I use the scope  every "good" night. It takes 12 minutes to be on target from the decision to  "GO".

Now to the point of this lengthy epistle.

First, please accept my apology for my initial reaction to your e-mail.   Second, please accept my sincere and heart felt thanks for steering me away from that "mass-marketed SCT" and toward the path to my Takahashi.

I cannot thank you enough.

Ron, you are more than welcome, and thank you for letting me share this letter with other readers. And for a humorous (not to mention highly instructive!) perspective that compares the average Department store refractor with a high-quality refractor, click on this link

Q: What eyepieces do I need? Is a Plossl better than an Orthoscopic?

All About Eyepieces

One of the first urges after buying a scope is to buy another eyepiece or two. Or three. Or twelve. Actually, you can get by quite well with perhaps three eyepieces for most of your viewing. If you're on a budget, two eyepieces can serve you well. But what kind of eyepieces to buy? And what focal lengths?

Let's start with types of eyepieces. There's a fantastic range of eyepiece designs on the market today; I'll cover the more common ones you're likely to encounter.

  1. Ramsden and Huygens. These designs both use a pair of simple lenses, and these days are typically found included with cheap imported telescopes. In days past, though, there were some very good examples made by Unitron, Goto and others for use with refractors.  Generally you don't see these today except in cheap version supplied with department store scopes.
  2. MA (Modified Achromat), Kellner and RKE. All three are variations on the Kellner, a Ramsden in which one of the simple lenses is replaced by an achromatic (color corrected) lens. Kellners can provide good performance for $30-$50. Good examples can be had from Meade, University Optics, Edmund (the RKE) and others.
  3. Orthoscopic. Once the prestige quality eyepiece among amateurs, the Ortho is a four-element design capable of excellent performance. The general wisdom is that the ortho is best suited to longer focal length (>f/8) scopes, but Brian Goodman writes to tell me he has excellent results using Pentax SMC orthos with his f/5.8 AP Traveler. Cost? $50 and up, depending on quality and make. The Pentax SMCs cost $185. University Optics has an excellent line of Orthos for $50-60 that are (IMHO) a far better choice than the typical $50-70 symmetrical sold as a plossl. (I am also advised by Gary Hand that most "orthos" are not true Abbe' Orthoscopics)
  4. Plossl. The Plossl seems to be the favorite eyepiece these days. It's quite versatile, works well with just about any scope and provide a fairly wide angle view (an apparent angle of around 50 degrees). They also work better with very fast telescopes (faster than f/5) than do orthos. The basic Plossl design is a pair of achromats, closely spaced. Some designs use a 5th element between these two. (Most eyepieces sold as Plossls are actually symmetricals- a similar  design that uses two identical achromats). The original (and still the only true) Plossls  from Clave' are quite expensive. You can buy inexpensive imported "plossls" (symmetricals) for around $50 from many sources. Better examples from TeleVue and Meade (the Meade 4000 series) cost $75 and up, and are worth it for the improved contrast and resolution- but they're still a symmetrical derived design with 5 elements, not a true Plossl of the Clave' design. University Optics has a US made 12mm "plossl" that's a cut above the rest of the midpriced Plossls.
The last few years have seen an explosion in new designs, like the various super wide angle oculars from TeleVue and (more recently) Meade and Pentax and others, but here we're talking about spending $150, $250 or more on eyepieces. Stick with simple designs for now. If you're on a budget, go with Kellners. If you have a few more dollars, get the University orthos or, for a very fast scope (like an f/4 Newtonian) inexpensive (under $50) Plossls.

If you can afford it, consider the Meade 4000 series and TeleVue plossls.

If you're ready to spend $150-300 for an eyepiece, you probably don't need my advice, although I will say I'm a fan of the Brandon eyepieces. I have a full threaded set for my Questar and a few others in standard unthreaded style.

But which focal lengths should you buy? There is in fact a rational way to make your selection, based on the notion of exit pupil size. The exit pupil of an optical system is the image of the objective lens (or mirror) that's formed by the eyepiece. The lower the magnification, the larger the pupil, and the higher the magnification, the smaller the pupil. Your eye can only accommodate a certain range of exit pupil sizes efficiently. If the exit pupil is too small, the image formed on your retina is too small to be adequately resolved by your eye. If the pupil is too large, the image of the secondary mirror in a reflecting telescope starts becoming visible, blocking part of the field of view.

Okay then, how do you figure exit pupil size? Simple. (exit pupil size) x (f/ratio of telescope) = (eyepiece focal length). So if you have one of the popular 8 inch f/10 SCTs, just multiply pupil size by 10 to get eyepiece focal length. For an f/5 scope, you'd multiply pupil size by 5.

Your lowest generally useful magnification is had with an eyepiece that delivers an exit pupil of 6 to 7mm. That means the owner of a f/10 SCT would need a 60mm or 70mm eyepiece to get the lowest useable magnification. The f/5 scope would only need a 30mm or 35mm eyepiece to get that same magnification, given scopes of the same size. Now you see why fast scopes (those with a low f/ratio) are often preferred for wide angle, rich-field views; 60mm and 70mm eyepieces aren't common (but see the following paragraph), although Celestron did have Ultrascopics up to 80mm, and I believe Docter Optics makes a 90mm that costs more than most of the scopes discussed here. Normally the longest focal length eyepiece you'll find will be a 50-56mm Plossl in a 2" barrel.

Surplus Shed has lately been making a line of eyepieces from surplus lenses mounted in plastic and metal barrels. They're very good, cheap, and available in focal lengths up to 85mm! The large plossls are only $39.50. You can find them at SurplusShack. I own several, including a 50mm Plossl I use as a finder witrh my TeleVue Pronto.

Maximum acuity (the ability to discern detail) is had with an exit pupil of about 2mm. Again, using the examples of the f/10 and f/5 scopes, you'd use a 20mm or 10mm eyepiece, respectively.

Maximum useful magnification is generally had with a 0.5mm pupil. For the f/10 scope that's 0.5 x 10 = 5mm. For the f/5 scope, it's 0.5 x 5 = 2.5mm. There aren't too many of those on the market. (Vixen makes one).

Now, sometimes it's possible to use even higher power under certain circumstances. In splitting double stars under excellent seeing conditions it's common to use an eyepiece that will deliver only a 0.25mm or smaller exit pupil. This would be useless for seeing planetary detail, but in splitting doubles we're just looking at the diffraction pattern of a point source (the star), not the star itself.

Incidentally, if you do a little basic math, you'll find that scopes with the same objective diameter will deliver the same size exit pupil for the same magnification, regardless of f/ratio. That's where the rule about a good scope delivering 50x per inch comes from. It's a limitation of the eye, not the scope. 50x/inch works out to an exit pupil of .5mm, just what our rule says is about the maximum you can expect to see detail at. If we do the math backwards we can also see that a 7mm exit pupil works out to about 3.63x per inch or aperture, so that's another way to look at it.

And just to make things really easy, here's a table with recommended eyepieces for different scopes:

Scope Focal Length
Lowest Practical Power Highest Resolution Highest Usable Power
f/5 32mm 10mm 2.5mm
f/8 55mm 16mm 4mm
f/10 70mm 20mm 5mm
f/15 105mm 30mm 7.5mm
As noted above, 70mm and 105mm eyepieces are pretty rare; if you need very low power, you may be able to get a focal length reducer, also known as a telecompressor, for your scope. Meade and Celestron make them for their SCTs.

Q: Can I use a camera lens as a telescope?
I was recently asked this question, and it's a good one.  Photo lenses often seem tempting for astronomical use, as they're quite cheap in comparison with many telescopes of similar quality. But there are a number of reasons they geneally don't work as well.
1. Lack of constrast and sharpness. Most lenses do not perform very well wide open. Exceptions would be the various ED lenses, which cost as much or more than many telescopes. Even so, most camera lenses are not figured nearly as accurately as are  telescope lenses, the best of which are routinely hand figured to 1/10th wavelength. Camera lenses are generally machine polished. And camera lenses generally have many more elements than do telescopes, which further reduces contrast.

2. Correction. A set of optics can only be ideally corrected at one focus. For telescopes, that's infinity focus; for camera lenses, it's much closer.

3. Field. Photographic lenses have to compromise between center and edge sharpness. Telescopes designed for visual use can concentrate on center sharpness. (There are of course flat-field telescopes designed for photography as well.)

4. Difficulty in adding visual focusers. Most camera lenses have an image plane  extremely close to the rearmost element, making it impossible to add an eyepiece. Nikon and others have made adapters that use one or more barlow-type elements to extend the focal length 4x or more to allow for eyepieces. A Canon 400mm/f5.6 lens would become in effect a 3" f/22 scope at a cost of $1100 plus at least $200 for adapters. You can buy (for instance) a TeleVue Pronto for $1100 or a TV-76 for $1600, either of which would be a far better performer- fewer elements, higher contrast, much more rugged, etc. And the Pronto, with the addition of a flat-field adapter, makes a great 400mm/f7 lens.

I think the short answer is that it can be done, but it's only practical if you already have the lenses and can find or make a suitible adapter to extend the focal length and provide increased rear focus. I wouldn't buy a modern camera lens to use as a telescope.
I *have* in the past experimented with older unmounted camera lenses designed for aerial cameras and other applications. The problem with these is that they're typically corrected for black and white or infrared film and don't deliver color free images without filtering. Still, they can deliver nice wide-field views at low magnifications.

Q: Can I use my telescope to look at the Sun?
Solar observation is a great way to expand your hobby to the daylight hours, and there are several safe ways to observe the Sun with any telescope. The first thing you need is a solar filter.

There are three kinds of solar filters. The first is something you only see on older imported telescopes. It's a small dark filter that screws into the back of an eyepipece. If you come across one, smash it with a hammer. Seriously! These are very dangerous to use. They will quickly heat up and shatter, allowing a potentially blinding ray of focused sunlight to enter the eye. Typically they were made for 25mm (0.965") Japanese eyepieces.

The safe modern alternative is a solar filter that fits over the aperture of the telescope. You can buy inexpensive ones made of laminated aluminized mylar ($20-50), or better quality ones made of partially aluminized glass. These will allow you to see sunspots, and to safely view an eclipse of the sun. You'll also need a filter for your finder- or a simple solar finder. (I've linked to a commercial unit, but you can make your own. It's just a pinhole with a target behind it.)

If you want to see solar prominences, and the detailed, granular appearance of the sun's surface, you'll need a narrow-band filter in addition to the full aperture filter mentioned above. At one time these were complex, temperature-controlled units that cost several thousand dollars, but today you can buy a filter that works as well for only a few hundred dollars. The serious Solar observer can buy a small, dedicated solar telescope complete with the filters like the Meade Coronado Personal Solar Telescope for under $600.

Around $1300 will buy a Coronado SolarMax II 60 RichView with 5mm Blocking Filter that can see even greater detail.

Q: I just bought a Bushnell/Tasco/other telescope at a yard sale. Is it usable?
Most of these telescopes consist of a passable objective lens mounted in a plastic and metal tube and focuser. The problem they all share is that they generally come with very shakey, almost useless mounts, and cheap, useless eyepieces. Typically they come with simple 2-element eyepieces of very short focal length- like 4mm. The eyepieces are not chosen for quality, but in order to be able to advertise very high, but useless, magnifications. You simply cannot get a useful 525x magnification out of a 2.5" lens; you'd be lucky to get 100x.

If you have one of these scopes, it can be made usable, so long as it's not a very cheap one with a plastic objective lens, or a lens less than 2.7" (60mm) in diameter. If you have a scope with a good objective lens, either tighten up the slop in the mount or build a simple, solid wood tripod for it. If you're lucky, you'll have one good eyepiece; if not, buy a good eyepiece of around 20mm focal length. You'll typically need a .965" diameter eyepiece rather than the now-standard 1.25" eyepieces; excellent 0.965"l diameter eyepieces can be had from SurplusShed very inexpensively.

(However... if the scope in question has a plastic objective lens, forget it. These scopes deliver a very blurry image that can't be improved.)

Q: How can I test a telescope to see if it's any good?

Good questions. Aside from the obvious checks- is the mount solid? Is the objective lens scratched or cloudy?- you can do a star test to detemine the quality of the objective mirror of lens. There's a good basic summary here, but I'll give a brief outline of how to do a star test. This is something you should do on any telescope you intend to buy, even that $20 garage sale special.

First you'll need a bright star to focus on, or, failing that, some kind of artifical star. That's pretty easy, actually. On a sunny day, if you focus a telescope on the reflection of the sun off a small, distant, curved object- a glass or ceramic insulator on a distant utility pole is ideal- you will have a small, bright image to serve as your artificial star. You could also hang a small Christmas tree ornament up 100' away, and focus on the reflection off that.

Make sure the scope has cooled down to the ambient air temperature. If you're taking a scope outside on a cool night, this could take an hour or two for a large scope.

Using the highest power available (at least 50x per inch of aperture) focus on the star. You should see a dot of light surrounded by at most 2 or 3 thin rings. Each ring should be significantly dimmer than the one inside it. If you see more, that's a sign of spherical abberation. If all you see is a dot with no rings, you may need more magnifications. If the image moves around and changes shape, that's a sign of turbulence in the air; you'll just have to be patient and wait for those moments of clear viewing. (This won't happen with daytime star testing on a close object.)

Next, move the focusing tube in and out, defocusting the scope slightly. You should see more rings appear. Now compare the images either side of perfect focus. They should be identical. You should see a series of concentric rings, very thin near the center, widening as you move towards the outside of the image.

If the images either side of focus aren't identical, that means there are some abberations in the figure of the lens or the mirror. Look at the slightly defocused images. They should be perfectly symmetrical. If they seem to bulge in some way, that's a sign of astrigmatism. If they're not perfectly concentric, that's a sign of coma. And if you can't see rings at all- if all you can see is a blob of light- that means there's something seriously wrong with this telescope.

Q: I hear that Mars is going to be really close to the Earth in a month!
In 2003, Mars made its closest approach to the Earth in almost 60,000 years, which provided an excellent opportunity for amateur astronomers. Since then, every year someone recycles an increasingly distorted email claiming that Mars is making a close apporach, or that it will be closer to Earth than the Mooon! Actually, Mars is slowly moving farther from the Earth on each orbit- but it will make a close pass again in another 59,616 years, so you may want to mark your calendar.
Q: Why should I take your advice over that of another web page?
Well, you shouldn't, really. At least you shouldn't take anyone's advice as the absolute gospel truth as to what telescope you should buy. You should take your time, shop around and educate yourself before spending $200 or $500 or $1000 on a telescope. I will say that while I do have advertising links to cover my costs, I try to be very upfront and honest about why I recommend one scope over another. I don't accept money from telescope makers to promote one scope over another, or one retailer over another.
Q: Okay, mister telescope expert- what do you use for viewing the skies?

Good question. I have owned telescopes ranging from a 2" Unitron to an 18" Newtonian reflector, including all sorts of reflectors, refractors, SCTs and Maks, on all sorts of mounts, ranging from simple camera tripods to a massive Losmondy that took me an hour to properly set up and polar align. For me, at least, I don't want a scope that I can't set up and have ready for use in 15 minutes. For that reason, I have three main scopes: A pair of 9x56 binoculars, a TeleVue Pronto on an Upswing mount, and a Quester 3.5 and a heavy duty tripod.

When I want to take a quick look at something in the sky, I grab the binos. For casual viewing of the moon, or wandering through the Milky Way from a dark location, I use the Pronto- especially as it's very easy to carry in a backpack. And when I want to take my time viewing planets or splitting double stars, out comes the Questar. It's also the preferred platform for piggyback photography. But if I lived in a rural area, with dark skies, I'd get a big Dobsonaian scope, and build a simple observatory with a steel pier set in concrete to mount my scopes.

A note on optical quality:

Many people wonder why apparently identical eyepieces can vary so much in price- and why someone would pay a fortune for an old Zeiss eyepiece made before WWII that doesn't even have any coatings. The answer is quality. The making of very high quality optics requires a lot of hand work, testing and adjustment if you wish to produce a really excellent optical device.

Take polishing. Optics can be machine polished; most eyeglasses have machine polished surfaces. They're also not nearly as smooth as are the best astronomical eyepieces. Roughness scatters light and reduces contrast. Achieving the kind of polish found on the best optics is neither fast nor cheap, but it really pays off when doing planetary viewing at 400x

Consider the variability of optical glass. Two different batches of nominally the same glass with differ slightly in their properties, requiring adjustments in the figuring of surfaces and the spacing of elements. More hand work. TeleVue notes in their ads that every telescope they make requires a slightly different spacing of elements for optical performance.

There are other factors as well, but these are a few to consider when you wonder why a 4-element eyepiece of a 1920s design costs more than a 7-element computer designed 2" ultra-wide eyepiece.


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