What are the disadvantages of the telescope?
140884
The only disadvantage of the telescope is cost.  The fact that they need motors to track stars is a cost factor.  The field of view degredation with magnification can be compensated for with high cost eyepieces.  The fact that they can only see light that penetrates the atmosphere isn't a disadvantage because we can't see that anyway.  There are disadvantages to different types of telescopes.  Some of the catadioptric scopes do not have as wide a contrast range on the Moon and planets as a refractor.  Refractors suffer from chromatic aberration (or "spurious color"). This is an optical defect that produces a faint pale violet halo around bright stars, the limb of the Moon, and the planets.  Reflectors, because of the parabolic shape of their primary mirrors, all have coma – an optical defect in which stars appear triangular or wedge-shaped at the edge of the field. Where as Dobsonian Reflectors give you the best aperature for your money, there size and maintenance (collimation) are considered by some as drawbacks.
58101
Simple: http://www.life.uiuc.edu/hughes/boast/sciencelessons/telescopes.htm\nAdvanced: http://www.funsci.com/fun3_en/tele/tele.htm
831645
Which one is not one of these disadvantages??\n\nI'm voting for a - you could use a CCD and computer with a prism.
665860
http://www.ehow.com/how_17057_make-simple-telescope.html
268357
option 4. coz a telescope helps us see images of gigantic objects, so a diminished image wrt object forms. also, the final image formed is upside down(though it is virtual) coz the ist image formed is real and inverted.\ntrust me, i just gave my phyics board exams.
417677
For refractors, the most common problem is chromatic aberration. In this, you get little rainbows around bright objects and a blurrier image around others. This happens because the lenses act like prisms. All refractors are subject to this, but some *very* expensive ones have it less. They fix this by using more than one type of glass.\n\nFor reflectors, the main problem is spherical aberration. This is caused by the mirror not being a perfect paraboloid. It is much easier to grind a sphere than a paraboloid, and most mirrors are first ground to a spherical shape. If the subsequent grinding isn't done right, the resulting images will be blurrier than need be. For decent images, the mirror's shape has to be within 1/4 of a wavelength of light, and for a good image it should be correct to within 1/10 of a wavelength. Considering how small the wavelength of visible light is, you can see how hard that is.
1105433
You could, but it would be huge overkill. The telescope's objective (lens or mirror) limits the resolution of the image in the focal plane. So you'd be using a microscope to examine (at huge magnification) that resolution-limited image. You'd see nothing but a lot of fuzz, even when in focus; and it would be dim fuzz at that, because you'd only be capturing a tiny fraction of the available light.\n\nI'd stick to standard eyepieces.
890617
Small observatory class telescopes can be as cheap as tens of thousands of dollars. The Keck telescopes, which are among the largest in the world, cost $94 million and the Hubble Space telescope, which is actually smaller, cost $1.5 billion.
1170213
It depends on what you need telescope for.  Things like Jupiter, Saturn, the Moon, the Orion Nebula will look great.  This is a great out of the box scope but it isn't a large one.  If you want to do a lot of deep space exploration you need a bigger/different scope.  There is an article at Sky & Telescope about chosing the right scope.\n\nhttp://skyandtelescope.com/howto/scopes/article_241_1.asp
354230
Greetings,\n\nFollow this link to Sky and Telescope magazine's website almanac.  Plug in your information and it will give you the info you requested.\n\nhttp://skyandtelescope.com/observing/almanac/\n\n-matt
850965
http://en.wikipedia.org/wiki/Keck_telescope
1056956
No, I read an article and it said that you need a strong telescope and lots and lots of astronomy experience. I was hoping I'd be able to see it too, but I have neither!
984480
buy two convex lens, both should have different focal lengths and it is advisable that you should buy lenses of high focal lengths. and a tube is also required.the length of the tube should be equal to the sum of the focal lengths of the two lenses.\nNow, make the bigger lens as the eyepiece and the smaller one as objective. your telescope is ready to wander through the universe.
1134720
Hi, great question.  I got a new telescope a year ago and have found a couple of excellent sites.  First try 'skyandtelescope.com'  this site has several features including a sky chart.  Enter your info, and it gives hour by hour info on whats up there to see, as well as info on upcoming events.  It offers 'how to advice' for telescopes, binocs and  astro photography.\nThe second is 'astromart.com'   this is one of THE BEST and most helpfull sites I have been to.  What a great forum.  Several active members are well known scientists and professors as well as very knowledgeable amature astronomy buffs.  No question is to stupid for them and you won't find a better place to gain advice and knowledge.   Questions posted are answered very quickly, usually in no more then a few hours, sometimes immediately.  Try both of these, I'm sure you will find what you need.    They are both  free of charge, believe it or not!!!\n\nLet me know what you think,  my s/n on astromart is lilkritter!!  Good Luck!
98059
The short answer is: No one really knows, since the details are classified. Also, the current satellite performance is probably not as good as what it CAN be. \n\nI think that comparing what astronomers are able to do with what the best satellites are able to do can be a bit misleading. \n\n1. The space telescope does not have to look through the air, with the water vapor and turbulence and dust. The space telescope has only the very outer reaches of the atmosphere to look through. \n\n2. The space telescope and ground-based astronomers do not have at their disposal anywhere near the resources that governmental organizations do. For example, the space telescope was not even calibrated, because there was so little money! It was only because of heroic efforts and a few minor miracles that the space telescope was brought into focus. The space telescope is basically a toy, and has barely been able to get funded for the last few years, and might be soon decommissioned. \n\n3. Astronomers just do not have the interest, the background, the training, the knowledge, or the resources to command the type of bleeding-edge technology that governments do. Astronomers for the most part are mired in phenomenology, and do not worry much about the details of pedestrian things like optics. Optics is, in general, disparaged by astronomers and left to the "engineers" and other lesser beings like mathematicians, physicists, statisticians, computer scientists, etc. Basically, astronomers hurt themselves with their attitudes and their culture. \n\n4. No responsible government is going to announce what they are capable of seeing with their satellites. All of this material is very closely held at best, and most likely highly classified. \n\n5. It is well known (or at least often reported in the newspapers, so it might not be correct) that spy satellites are so big and so heavy because they bring a large reserve of fuel with them so that they can be lowered and raised as needed to see various features and details. Apparently, they do not always orbit at the same altitude. \n\n6. It is quite possible to combine imagery from platforms such as multiple satellites, planes, high altitude balloons, etc. to improve resolution considerably. It is hard to know the extent to which this is done, or if it is done, because of course the area is shrouded in secrecy, so we do not know. But the question was, how detailed CAN it be? Well you COULD use multiple sensors on multiple platforms, unlike the Hubble telescope (in fact, multiple sensors on the ground are able to beat Hubble now). \n \n7. As a gross upper bound on resolution limits, look at the mutually agreed upon limits on size of warheads etc by the Russians/FSU/USSR and the USA, for example (typically, the silo doors would reportedly be opened to permit treaty inspections, according to newspaper accounts anyway). These specifications in the treaties imply MUCH higher resolution than the some of the numbers given here by others. And remember, these are the mutually agreed-upon resolutions by two very suspicious adversaries, who do not want to give anything away. Both have to be able to achieve these resolutions, and probably are capable of far better resolution. \n\n8. Having looked at Dawe's limit, and knowing a bit about resolution, I can tell you that it is not particularly useful as an indicator of achievable resolution. How close we are able to come to ultimate resolutions depends on how many resources we are willing to spend, and again since it is classified, it is difficult to know.\n\nTherefore, to answer the question how detailed can satellite imagery be? The answer is, VERY. How detailed is it? We do not know, since it is classified.
214155
I am gessing that you want to knoe about "optical" telescope.\n\nThere are basically two types of optical telescopes.\n\n1. Refrective Telescope\n==========================\n\nThere is an objective lense that creates a virtual image of the object you are trying to see very close to asecond lense called the eaypiece. The eyepiece magnifies that virtual image many times bigger.\n\nMagnification = focal length of objective/focal lenth of eyepiece\n\n2. Mirror type (Newtonian)\n==========================\n\nThis type uses a parabolic mirror to create a virtual image of the object you are trying to see very close to the eaypiece. The eyepiece magnifies that virtual image many times bigger.\n\nMagnification = focal length of mirror/focal lenth of eyepiece
952358
Here is a site that gives you several sources for 20" telescopes.\nhttp://www.bigtelescopeguide.com/20-inch-telescope-mirrors.html