The Ebay listing provides the only clues you have about the telescope, whichever the manufacturer.

What is written in the Ebay listing: 

THIS IS A MAGNIFICENT AND HUGE PROFESSIONAL OPTICAL INSTRUMENT

Professional astronomers use observatories with reflecting telescopes with a minimum diameter of around 40 inches (1024 cm). The finder for such a scope would be something like an 8 inch refractor. If you want one of those, budget for about 14 million dollars US for starters. Enough said.

THE OPTICS ARE DIFFRACTION LIMITED

Never mind what 'diffraction limited' actually means. Let me just say that having diffraction limited mirrors is great, marvelous, magnificent and not 'Yuk!!' For new, expect to pay £180 plus for the optics alone depending on aperture starting at 4 1/2 inches (usually £250 ish for the 6 inch mirror). That's just the parabolic and flat mirrors. Spherical mirrors cannot be made diffraction limited and don't let anyone tell you that statement is wrong. Spherical mirrors cannot be made diffraction limited unless you can change the laws of physics.

FULLY GUARANTEED

Against what? Plagues of boils, civil riots or blue ice falling from planes?

WITH A TRIPOD THAT IS AS SOLID AS THE ROCK OF GIBRALTER

How many sections does it have and is it braced across the legs? Stable tripods are of single piece braced legs or two-section legs that adjust for height. Any more sections than this should be suspect for stability unless they are tubular stainless steel with at least 3mm wall thickness (and those will cost you).

MADE OF SOLID BRASS WITH BRASS DRAW TUBES AND COVERED IN THE FINEST LEATHER MOUNTED ON AN ORNATELY CARVED BALL AND CLAW STAND

You will enjoy polishing it frequently.

EXPLORE THE GLORY OF THE HEAVENS WITH THIS MAGNIFICENT OPTICAL INSTRUMENT MUCH FAVOURED BY ALL PROFESSIONAL ASTRONOMERS. SO MANY FREE ACCESSORIES YOUR HEAD WILL SPIN. THE TELESCOPE BODY IS FINISHED IN GLOWING WHITE AND RED USING THE LATEST TECHNIQUES DEVELOPED BY NASA FOR TREATING THE SURFACES OF ITS ORBITING CRAFTS. UNSURPRISINGLY, THIS PROFESSIONAL INSTRUMENT WOULD GRACE ANY ROOM IN YOUR HOUSE AND IMPRESS YOUR FRIENDS. GET THE BEST EVER VIEWS OF PLANETS, STARS, STAR CLUSTERS AND OTHER GALAXIES. EXPLORE THE MOON USING OUR FREE MOON MAP THAT SHOWS THE LANDING SITES OF THE MOON MISSIONS AFTER THE FIRST LANDING IN 1969. THIS TELESCOPE AS WELL AS ITS FREE ACCESSORIES IS FULLY GUARANTEED FOR LIFE. YOU WILL NOT BE DISAPPOINTED. BUY ONE NOW WHILST STOCKS LAST BECAUSE THE AVAILABLE STOCK IS RAPIDLY DWINDLING AND IS NOT EXPECTED TO LAST VERY LONG AS THIS MAGNIFICENT INSTRUMENT IS IN SUCH HIGH DEMAND ALL OVER THE WORLD.

Excuse me. Can I ask you a question? Is this a refractor, a reflector or a simple cardboard tube? It would be very nice to know something about it.

 NOW BE CAREFUL

Refractors benefit from a hood that acts like a lens hood on a camera lens. It is just a tube painted dead black on its inside that screws into the front of the telescope and prevents stray light from hitting the main lens. Usually, the image quality will benefit because the image will be more 'contrasty'.

Reflectors don't need this sort of device because the tube itself does that job (the mirror is at the bottom of the tube).

Very often, you will see photos in listings of cheap efforts that look very impressive because the business end is of a much larger diameter than the rest of the tube.

Now unscrew the hood and the tube that contains the optics is just a narrow aluminium or plastic thing that in itself, would not impress your dog.

Is such a hood worthwhile? It blocks stray light and if long enough, will cut down the amount of dew (water droplets) forming on the lens on damp nights if the length is something like four times the diameter of the lens. Thing is, with the well designed scopes (Celestrons, Meades, etc), the designers compute the hood length to balance field of view with different eyepieces against preventing dew formation.

Think. The diameter of the lens is 60mm. Now screw a tube on the end 500mm long. Look through the eyepiece and you will see a small circle containing the image surrounded by black, which is the out of focus inside of the 500mm tube.

With the cheap efforts, it is more likely that when the scope is made down to a price, someone takes a flying guess concerning the length of the hood with only appearance in mind.

THE ALL IMPORTANT MISCONCEPTION:-

MAGNIFICATION (up to x 500, x 600, x750 etc).

Many scopes, especially the cheaper ones with a small aperture are advertised with big magnifications as the big sales feature. Those not in the know think that is great. It is not. In fact, it is a cheap con for the unwitting.

You do not need big magnification because in the English climate you need only 30 times the aperture of your lens or mirror in inches. That is the maximum magnification that the English climate will allow most of the year. On a handful of exceptional nights, 50 times the aperture. Any more is unusable.

For example, if the aperture is 6 inches, the maximum magnification that will give you a decent image is 6 x 30 = 180. And that’s it. Jupiter will be nice and you will certainly see the rings of Saturn provided that the optics are of decent quality. The 6 incher can be used with a long focal length eyepiece at a magnification of x20 to look at extended objects (nebulae) and the Milky Way.

In any case, at x 500, with a floppy tripod and fifth rate mounting, the image is wobbling in and out of view, is fuzzy, out of focus and broken up (if you see anything at all). That sort of magnification just magnifies the imperfections in you equipment. That is all that extra unusable magnification does.

For planets, no more than x230 but for star fields, use the smallest magnification your scope can handle. The lower the magnification, the wider the field of view and vice versa.

Please do not go magnification crazy at the cost of everything else. Magnification is the least important thing. Surprisingly, at a magnification of x60, the field of view is so small that you will find it difficult to find the full Moon in your eyepiece even if you carefully line up the scope on the Moon.

If you want to go crazy, go aperture crazy and you won't go wrong. A 10 inch scope is better than an 8 inch scope which is better than a 6 inch scope and so on, provided that they are all of equal quality. But then other Parts go into this more fully.

The English climate is referred to but if you do not live in England, take the English climate as your own and you will not go too far wrong. If you live in a desert (no lights within 100 miles), 60 times the aperture in inches is fine with excellent optics and very good eyepieces (a must for the 60 factor).

It would be better to spend say £200 on a much used 6 inch scope made by a reputable manufacturer than £200 on a brand new 8 inch or even 10 inch scope made by the Hang em High Company Inc. Ltd. based in Conemwell Bay, Antartica. If a scope has had a lot of use, that should tell you that the seller has loved using it. People give up on low quality instruments. Remember that lenses and mirrors do not wear out just because light has been reflected or passed through them. However, surface silvered mirrors do require re-silvering every 8 or so years and that will cost in the region of £50 + depending on size and what needs to be done.

This aspect dealing with magnification is important enough to provide an explanation.

With terrestrial telescopes and binoculars, you need to make things appear bigger. If it doesn't, what's the point? They are telescopes that produce a magnified upright image

Stars look like points of light to the naked eye. What do you see when you magnify a point of light? It remains a point of light even if you magnify it 1000 times. The whole purpose of an astronomical telescope is to funnel light gathered by a lens or mirror into your eyeball. The more light gathered, the more stars you see and you can see their colours. The least powerful eyepiece will give what you want, the widest field of view for an amazing spectacle. That means the bigger aperture 'light bucket' gives a better view than the smaller 'light bucket'. Now push magnification back way behind the importance of aperture.

If you are still a non-believer, go into a photographic shop and ask to try out two pairs of binoculars. One with the smallest lenses (like 10 x 30) and one with bigger lenses (like10 x 60) and see which gives the brighter image. Then ask yourself why.

WHAT TO ASK THE SELLER.

Unless the listing is clear:

a)   what is the clear aperture? You will know the focal length so work out the f/ number. FOCAL LENGTH DIVIDED BY APERTURE = f/ NUMBER.

For a small refractor, anything more than 10 - move on. For a reflector, anything more than 10 - move on.

b)  what accuracy is the lens or mirror in wavefronts of light? The shopkeeper does not know or there is nothing in the literature? If so, ask the seller if the telescope comes with an optical certificate from the manufacturer stating the specifications of the optics. If the seller has not the faintest idea what you are talking about or says it comes with no certificate - move on.

c)  what is the focuser, plastic or metal? All thin plastic or the seller cannot say. Move on.

d)  what eyepieces are supplied and are they one and a quarter inches or two inches? They are 0.96 inches or some odd dimensions - treat it as a toy.

e)  what sort of bearings does the mounting have? “It uses bolts and screws but no proper bearings that can be adjusted.” Know where your tool kit is.

f)   are slow motion drives worm and wheels made in metal or are they plastic? Do they have much backlash and play? If they are friction drives - passable if made well. If they are cast aluminium, since when can you cast an accurate gear instead of using a proper gear cutting tool on a lathe? For those not familiar, you cast a gear by pouring molten aluminium into a mould, much the same as using a cake mould.

g)   is the tripod braced across all of its legs to make it more rigid? It has 27 sections so it folds up to 4 inches for convenient storage. Leave it in storage. It will be worse than useless. If the scope comes with a table-top tripod, ask the seller if it also comes with a heavy, rigid table to put it on. People who settle for a refractor on a table-top tripod usually end up in the garden on their hands and knees with their heads in an ant nest.

h)   are counter-weights supplied with the equatorial mounting? “No. The design of this mounting is unique so that counter-weights are not required.” It is an alt-az mounting, not a German equatorial. However, it could be a fork mounting and the photograph will show that.

i)  is the mirror spherical or parabolic? “There is nothing in the literature.” It is a cheap, thin spherical mirror.

j)   what sort of guarantee is given and do you have to pay postage to and from the other side of the world when you return the scope to the manufacturers? The seller says “if anything goes wrong, just e-mail me.” And then?

h)  does the equatorial mounting make things easy for you by having a polar telescope fitted into it so you can more easily line up on the North Pole of the sky? A polar scope makes life so much easier but if the mounting does not have one, you need to know exactly what to do. Does this scope come with full understandable instructions that are not just a translation from Mandarin into German and then into French and finally, into English? For example: place utmost mount to the ground screw turning frequently at your leisure until right thinking says good. What the heck is an utmost mount? You then turn whatever the ground screw is and it suddenly shears off. Big deal !!

i)   if this thing is being imported from Plotzk in Tibet, will import duties from a non-EU country be added to the price? So what is the final price and how much postage forms part of that? Is it £60 postage, £40 customs duty and £4.99 for the full telescope kit? If you must, holiday in Plotzk and pick one up locally.

j)   is the primary and secondary mirror Pyrex? “It is of the highest quality.” It is plate glass and will twist and turn at different temperatures. The mirror is made of a circular slab of glass (called a blank) and ends up curved on one side which supports a very thin layer of reflecting surface coated on it. Unless the slab is 'rock solid' under most conditions, the reflecting surface coated on it will not function properly.

A dealer in an ebay shop should be able to answer all of these questions. If he does not know, it may be very convenient for him not to know and you are on your own. A private seller is unlikely to know most of the answers.

You may see listed on Ebay a rubbish scope on a worthwhile mount or vice versa. It may be profitable to buy what is on offer and throw something away just to get the other piece.

So when will your questions on what to buy and how much to pay be answered? Not yet because there is more to be familiar with before those questions are answered.

In Part Three, you will find a few more things to consider not dealt with here, like how heavy is this thing going to be?