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Telescopes, I dont sell them! a quick guide, Newtonians

torana68
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Telescopes, I dont sell them! a quick guide, Newtonians
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I DO NOT SELL TELSCOPES! I use them and have a lot of fun!! this was writen to help you buy something usefull. ( if it does , could you tick the "yes" at the end pls.)

Rule number one - you get what you pay for!

Rule number 2 - If you dont know find out first!

 is this going to be your first telescope? then your at a huge disadvantage and sellers are going to take advantage of that!

You like astronomy, or at least the thought of it, pop into a newsagent and get a copy of one of the astranomical magazines for your country (Australian Sky and Telescope for example). Look at the prices, read the articles, NOW THINK! ..... is that 99c start Telescope really the equal of the $2000 one. NO ITS NOT, its probably junk or a childs toy.

The size of the apparture and the quality of the optics is the important bit

A Newtonian is the fatter telescope, also known as a "Reflector" as the light is reflected off mirrors into the eyepiece. They can be called "Dobsonians" but this is a reference to the style of mount, a "Dobsonian" is a "Newtonian/Reflector" on a Dobsonian mount, these are cheaper than the German Equatorial (GEM) mount but have many good points.

Newtonians need to be adjusted occasionally and the mirrors will require recoating after 10/15 years (Never touch the mirror! clean it only if absolutely necessary , find out why and how before you touch them!!) There are huge numbers of dud telescopes on EBAY.

dodgey dealings

      Beware adds for 1000x 'scopes, this is  rubbish, the best 'scopes for home use rarely go past 200x magnification, this is with the best optics on the best nights. 1000x? forget it.

If it says"short tube" forget it, most likely rubbish avoid these like the plague

  Also watch out for the recommended retail price scams where people quote a stupid RRP to con you into thinking your getting a bargain , this one is around in various guises and can involve bogus web pages quoting the said RRP to lure you into thinking its all true…. Only shop or compare prices at known trusted retailers.

 If you ignore everything else here  buy one of these:

  ... at least you wont have wasted a lot of money and you see just as much as you would have with junk!

      If you get caught, as many have, remember the return postage could be a huge strain, no one will pay for return postage, you get stuck with that, shop locally! shop smart!

get a guarantee of a Parabolic primary mirror, no guarantee DONT BUY IT! if they dont know search for the makers site, if its not a well known brand DONT BUY IT!!

you need a parabolic to get fine detail in all but the longest focal ratio Newtonians, and there are not usally any of those on EBAY ! dont believe anyone who claims to know better!

 

 

     This is a Chinese F/4 8" , 30mm eyepiece (29x), I can use a 10mm (88x) on the moon but anything else is hopeless due to poor quality optics, even at 10mm its getting fuzzy, these go for between $200 and $500 on Ebay  (my Ronchi tester says spherical mirror)

     This is an old Bintel 4.5" F/8 (Japanese made), 30mm eyepiece (86x), no problem equalling the view of the 8" F4 in fact you can see more definition, and no problem taking much more magnification, 6mm works ok (270x), mount is a bit wobbly, but not bad fun, small and light ,this one cost me $70 off Ebay (parabolic mirror)

     This is an old "Amateur Astronomers Supply Co"  8" F7 (got one? email me, would love to see photos) , 25 mm eyepiece (60x),  the mirror coating is way past its best, Ill repost after its recoated but it out preforms the Chinese F4 by a masive amount due to superior optics and longer F ratio. Still even with its worn coatings I can use 5mm eyepiece (300x).  This cost me $300 via Australia Astronomy buy and sell.  Its big and quite heavy being solid steel, everything is solid and secure (Parabolic mirror). With Older reflectors remember to find out the condition of the mirror coatings, they are expensive to have redone properly. Over ten years old you'll need to check.

     The magnification of a eyepiece is effected by focal length, a 30mm in a F/4.5  gives 27x but in an F/10 gives 70x. The size of the mirror also effects the maximum usefull magnification, there are various opinions but as an example a 4.5" can be used up to 200x a 6" to 300x , 8" 400x etc.

Bigger mirror = more light , which allows more magnification , which gives you more detail you can see (assuming its all good quality stuff) = awesome!

Small or cheap mirror = not much light does not allow much magnification/not much detail = no fun 

     Remember though, if the conditions are bad for viewing.... you wont see much anyhway no matter how much you spend!

YOU WILL NEVER see anything as small as a Lunar Lander on the moon no matter how much you spend (unless you can buy your own Hubble like space telescope), nor will you see images like the ones in books (you will if you buy something over 25" and have a place to set it up in a area free of city light pollution).... but you can take good photographs with good equipment, you dont have to spend millions or buy a huge Telescope, just buy what is recommended by people who have been in the hobby for years, rarely does this sort of stuff turn up on Ebay though , its usually sold from one club member to the next.

        For a good example of the size of Planets in your telescope Google "Backyard Voyager" and look at the "eyepiece views" page.  looks to me like the photos there were taken with a very good quality telescope, dont expect this from an el-cheepo, expect a more blured appearance. Dont expect much in a 4 1/2 and as I said dont go smaller that this in a Newtonian.

EBAY weirdness, I'll update some weird things said in their listings now and then

"Zoom in on Saturn's rings, the Moon's craters, the International Space Station.... "      errrr no that wont be happening, all of these "zoom" telescopes are dodgey, as there is , just for a start, no zoom set up , and the space station is going at 27,000 KPH , good luck trying to watch that through a dodgy wobbly little junk scope :(

"Due to the earth rotation celestial objects will drift out of the field of view without an electronic motor drive."   .its not too hard to adjust manually to compensate for this, a motor drive is nice but not necessary, it also requires you to set up the mount correctly or it wont follow anything anywhere

"Do you want to catch the moment that the meteor falling across the sky?      Using your eyes might be  better, impossable to follow a meteor with a telescope

"Take advantage of the moon filter, you can enjoy the charming moon at night without burning your eyes!"   what?

"you can be sure to capture that amazing solar flare"  seriously, you will be permanently blinded loooking at the sun through anything, this is beyond stupid

"2x Barlow lens, make it clear"  here's a seller who has no knowledge of telescopes

"It is a genuine telescope not a cheap Imitation" pretty funny that sort of comment, if you have to say that it probably is an imitation one!

150mm (6 inches) concave objective mirror: all mirrors are concave, this does not mean parabolic, in fact I'd say it's an attempt to con you by not admitting to a spherical low quality mirror

NEW BLACK TELESCOPE GIANT 6" MIRROR: ? 6" is NOT giant, these days probably small, this seller has various color telescopes ,Color does not affect anything, if anything the fact he has various color ones indicates chinese cheapie to me

"500x ZOOM".  This turned out to be a 4.5" and with nothing anywhere that zoomed? ... junk Im afraid. Lots of "zoom" telescopes about at the moment, what is it with this word? is it the latest "come in sucker" word?      "New high end huge professional 114mm".  Another dodgey one... unfortunately a professional wouldnt buy one of these for his grandkids fifth birthday, "high end" and a price under $800 for a 4.5"? I dont think so ... and "Huge" well I dont know about you but 4.5" of anything isnt huge. Truth in advertising can be hard to find !!

     Another not so good one ..."This unit is one of the largest available commercially and has massive light gathering power, it is a high quality reflector telescope. The combination of an enormous 8" mirror and a remarkeable focal length of 1000mm has been popular and proven for many years. It enables a fascinating observation of the nightly sky in unimaginable clarity"   8" was big in the 60's its not now, its a good size but much bigger ones are now easily purchased, the focal length is only remarkable by its shortness ! this one looked like one of the $200 Chinese f4's similar to one I bought recently for its mount, it was capable of fuzzy views of the moon and not much else, you can see better with bynos! but at the $200 I paid the mount was ok ( I have seen the same one with prices up to $500!!). These F4's (and other cheap junk) are being sold from Germany and locally in differing colours and brand names, you'll find they might offer a refund but you'll be paying the postage back to Germany or wherever, dont waste money on rubbish! Its probably fashionable to pull the wool over peoples eyes with BS but not the best way to live your life , buyer beware!

 

this is a Chinese 8"F4, it does not have a parabolic mirror (the ones that they make that do look a little different) ignore silly claims of recommended retail of A$999, they are sold at a profit for A$199 and worth somewhat less, you wont see anything much with these. The colours change, some are silver, some are implied to be from "Germany" (is there a place called Germany in China? :)  ) the quality of the mirror is the same ......99c quality! the ones with a good mirror may be worth looking at if the price is right.

Mirrors

     Is it a spherical or parabolic mirror? forget spherical mirrors for reflectors under a focal length of F9 .... nearly all the cheap Chinese 'scopes have spherical mirrors as they are cheaper to produce. Some Chinese makers are now making parabolic mirrors, look at these ones if the telescope suits you and your budget.

     76mm mirrors (3") are no good for anything astronomical, I have a 76mm F9 and 76mm F12 here and you cant see much more than the moon, even then at low magnification, they are toys for children, FORGET 76mm!!!!! no one makes quality in this size, maybe 80 years ago, not now, only rubish is made in this size.

     114mm , or 4.5", is a good size for a reflector/Newtonian telescope for a beginner, dont go smaller than this. Size matters here, the bigger the mirror the more you can see. 4.5" is NOT big. There are some quality ones made in this size but a lot of rubbish, most now go for 8" so thats what the quality makers are building.

     Eight inch is good and can be carried without too much trouble, ten inch would be great if you can afford it. Sixteen inch is out of reach of most but is something everyone who dabbles would love, it probably wont fit in a small car though. Look up the SDM Telescopes site for an example of quality manufacture ,also try Obsession 'scopes they have collapsable telescopes that are big in mirror size but will fit in a small car.

MOUNTS

Not a lot of choice either German Equatorial (GEM) or Dobsonian both have good points, Dobsonian is cheaper to make so the theory is the money saved can be spent on better optics. Equatorial is the one for photos, but only well made ones, there are a lot of cheap GEM's about that are not worth the hassles.. There is another called "alt azimuth", usualy its the cheap and nastys that have that sort of mount

,

left is a Newtonian on a "Dobsonian" mount on the right on a GEM

GOTO

     A goto Telescope has electronics to guide it, this can be expensive, if you get one make sure its from a known maker and you can get software updates .You are probably better spending the extra on good quality optics, its the optics that let you see things, the electronics just point the telescope.Use your in built computer (the one between your ears) to find things in the sky.

Focal length

     In a reflector a focal length of F4 is more suited to the advanced person who knows what they want, its not suitable for high magnification, these do show a large area of the sky. Longer F ratios, F8 for example, show smaller areas but can be used at high magnification. Look for something around F6. Beware the synthasized focal length telescopes, dont expect 99c optics to cope with this sort of trickery (this is apparent when they say "focal length 1000mm" when its obvious the physical length is half that).    

       So... before you decide , read magazines or books, search the net, maybe even join a club, the answers are out there. At the very least get some idea of what you are likely to see through a particular scope. As an example my cheapie 4 1/2" gives good views of the moon, I can see Jupiter and 4 of its moons but Jupiter is only about 5mm across ( as you look , might take some imigination to understand) . Pluto would be a very small pin prick of light on a good night.

   A couple of parting thoughts, Google "buying your first telescope in Australia" its a good read. Try on line groups like "Cloudy Nights" and "Ice in Space" for info or try "Australia Astronomy buy and sell"  

"If you want Ferrari preformance dont buy a Hyundai - you'll be dissapointed!"

if this was helpfull or even just interesting please tick the little box below, ta, Roger

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