Which telescope to buy?

this video is intended to give you all the important needs now information that you need to decide what's the right starter scope for you until the scopes do two things they allow you to see faint objects and they allow you to see small objects faint objects and be outside our solar system and they tend to be big and fuzzy the so-called deep sky objects you know galaxies globular clusters nebulae supernova remnants and so on the small objects tend to be bright double stars star clusters planets and so on magnification is largely a red herring here it's basically all about aperture the ability of a telescope to see faint objects basically oh should the square of the aperture so that is if you double the size of the aperture you get four times as many photons and that allows you to see much fainter objects the larger the diameter of the telescope the smaller the object the telescope has the capability to see but this time it basically goes linearly with the aperture that is you double the aperture then you can see objects about half the size so where's the problem I hear you ask the begin scope the better right well to a degree yes however there are other limitations on the telescope the first and most obvious is the sky all scopes are essentially useless under a cloudy sky but even if it's not cloudy the sky is commonly a greater limiting factor than the telescope if you're looking at framed objects such as nebula these tend to be big and fuzzy and so the darkness and the clarity that's basically how transparent the skies are the principal factors if your skies murky or is a lot of light pollution or there's even a full moon in the sky you can lastly forget about it a big scope under those circumstances is just an expensive way of making it hard to look at the stars small objects tend to be bright like planets and double stars so the clarity of the sky is not terribly important however the stability of the atmosphere is crucial I mean you know that shimmy you get on a hot road while the moon is about half a degree in size and a big planet like Jupiter is about a sixtieth of the angular size of the moon and a good scope can in principle resolve up to about six the features across that desk so as you can imagine you need a very still atmosphere to fully capitalize on that the bigger the scope distiller you need the atmosphere to be to take full advantage of it indeed the resolution purposes once the scope gets up to at 30 centimeters or 12 inches in diameter the atmosphere is essentially never stable enough and always limits the performance of the telescope so let's assume for the moment that the skies are excellent the next major factor is ease-of-use most scopes are not permanently set up and so they have to be moved outside and set up a scope that weighs as much as a small car might have superb capabilities but if it takes an hour to move outside and set up experience has shown that it'll simply tend not to be used typically the largest scope that can be handled by one person is about a six-inch refractor or a 12 inch reflector type scope and because telescopes typically deal with resolving such small objects the telescope's performance is frequently atrociously subpar until it is cooled down to about the outside temperature and the larger the scope the longer that takes it really all depends what sort of astronomy you're going to be into if you just want to scope that you can take out into the garden and star gaze for half an hour or so having to set things up and let them cool down for half an hour or so can have a significant deterrent effect now the scopes themselves come in two basic forms those that focus the light by lenses and those that use mirrors those that use mirrors typically have a secondary mirror in the optical train and this obviously reduces the light gathering capability of the telescope and also lowers the resolution in practical terms what that means is you get more contrast images out of refractors but most refractors have the problem that they focus the red light and the blue light in different areas the so-called Accra mattes pragmatically that means the bright objects like planets get this purple halo that you cannot get rid of well come on you can do it by putting extra lenses in the optical train the so-called apochromatic refracting the scopes about ten times as much as an equivalent aperture reflector type scope having said that I have used these scopes and dark skies and they are almost magically beautiful to use in the way that the stars fall if you'll excuse the poetic language into impossibly sharp pinpricks of light on a black velvet sky now you need to mount the scope you see when you're looking at this very small portion of the sky first of all of course you need a very sturdy mount and that's really important but secondly the Earth's rotation becomes a bit of a the earth is hammering around such that the sky apparently rotates well once per day and if your scopes not driven to compensate with that rotation you'll just observe the object you're looking at drift out of the frame depending on the power but typically in about a minute the answer of amounts of course are much cheaper but you have to compensate for the Earth's rotation by actually moving the telescope and that can be a pain driven scopes these days are almost exclusively the so-called go-to scopes go-to escapes basically require your location on the earth the time and a few star observations such the scope knows in which direction it's pointing so that you can drive the mount track objects the setup might only take ten minutes or so but it's still a pain in the ass and even more so if you don't have a good idea of what you're doing however after that most scopes will allow you to request an object which the scape will intuitively find for you but if the scope gets now it'll move you'll typically have to realign it now the go to mount can save a lot of time in messing around with star atlases and finders but it also removes a lot of the organic feel of exploring and getting to know the sky the scope just pans and tilts and after that all you do is look into the eyepiece so these are the basic metrics you need to assess when choosing which scope is right for you after that it basically boils down to how much you're willing to spend if you're looking for a cheap entry-level telescope I would recommend the biggest Dobsonian house essentially an untruth an ultrasonic mounted Newtonian reflector that you can afford it's the cheapest way to get aperture light buckets give you a lot of versatility they're great for looking at faint objects and they will give you good views of the planets however they're not typically trifa and that means that you have to find the object yourself and track them yourself my next choice would probably be an alt Assamese mounted Schmidt go to scope relatively good value for money in terms of aperture per dollar and the Scopes are driven which allows potential for astrophotography for casual stargazing use and if cost release and an issue I would probably go for a altazimuth mounted foreign chopper chromatic type refractor fast to set up beautiful to use and due to the build quality on the instruments collimation of the optics is essentially never required now the build quality on scopes these days is all around fairly reproducibly high but of course this is the internet age and and when you actually think you're buying scope go to somewhere like amazon and check out the ratings after that the cosmos is yours to explore in the sidebar there is a description of some of the telescopes i bought and used over the years ranging in price from about thirty to three thousand dollars

Channel: Thunderf00t

Views: 1,841,698

Keywords: which, telescope, to, buy, beginner, buyers, guide, buying, first, starter, start, fun, with, astronomy, dobsonian, newtonian, refractor, reflector, Maksutov, Schmidt, Cassegrain, achromatic, apochromatic, amazon, for, ratings, purchase, jupiter, moon, planets, night, sky, nebular, stars, equatorial, altazimuth, tripod, scope, lunar, eclipse, saturn, mars, venus, celestron, meade, orion, televue

Id: sAzhOSbxMiI

Length: 7min 42sec (462 seconds)

Published: Fri Dec 17 2010