I have a 13" Reflector "Newtonian"~ are they hard to Collimate?
965276
Newtonian telescopes are especially easy to collimate, since there is only one curved mirror and an eyepiece.  Basically, you need to get the eyepiece centered in the image formed by the mirror, you have to get it pointed in the right direction, and you have to get it focussed.
481113
It depends on what kind of mount you have, it seems you either have a German equitorial or an altazimuth mount.\nIf you are leveling & alighning on polaris and the blank end has a reference mark & 0 deg. north on the scale is in the center of two tripod legs the zero faces south.
197214
You need a telescope to see them.
370114
they are cheap compare to electron microscope.\nbut there is limitation of zooming large.
680736
Well you would need light boxes, mirrors and prisms\n\nyou could ask them to do all the things to do with angles of light going through the prisms\n\nand you could ask them to build periscopes\n\nI can't remember my optics very well but if its possible then you could ask them to measure the magnification of the curved mirrors.
709999
Surefire's are amazing.  The entry level is worth every penny ($33) the others I am not so sure about.  I have seen SF mounts with light for $250 and I know I could fabricate something for much less.    Do you have a rail that you can mount to?  If not, you need to solve that first.  The second problem should be elementary, finding or fabricating a mount with an appropriately sized opening for the light should be pretty easy.
730616
Give this site a look.  And I think everything on it is under $300\n\nhttp://space.about.com/cs/telescopes/tp/tpbegscop300.htm\n\nGood luck.
860328
No,\nI wouldn't say that's entirely impossible but it'd be a small technical challange.\n\nIf you can't afford a telescope you should contact your local astronomical society. Many will let members borrow telescopes for free or they may be able to tell you of a star party where you can go and others will let you look through their telescopes.
64828
This guy built his own LCD projector. He used a double convex lens like a magnifying glass lens, however you are probably going to need a better light source than a flashlight. The flashlight has the right type of parabolic reflector, but just not enough light. Anyway, it will take trial and error to figure out the best configuration between the light and the lens, but should work. The LCD project is very similar and should give you some guidance. DIYaudio.com has some forums where you might get more advice.
196862
It's probably just that you need more time to get used to them.  I have blended "omnifocals," and I spent about the first week playing the game I call "find the focus."  You roll your head up and down (looking like an idiot if anyone's watching), finding the best focus you can get for a given viewing situation.  You may find, for example, that at times you have to hold your head up in what looks like a snobbish way, or roll it down as if you were being shy.  \n\nIf you don't adjust after a week or so, you might ask the guy who fitted the frames to your face whether they need adjusting.
1055664
You can do it with a laser a small circular obstacle (1cm diametre) and some lens. You built a telescope like picture to have 2cm diameter beam  you put the obstacle in front and you regard at 20 cm from the target
938764
you need harder wheels and a higher ABEC bearing for them.:)
749447
Hi. A good one might be Regulus because it lies pretty close to the ecliptic and is very bright. But you can use any star. For much better accuracy scientists use quasars due to their vast distance. This eliminates parallax error.
1018864
You can purchase a Tasco 4.5 inch reflector telescope that comes with eyepieces that give magnifications of 50x 100x and 200x. \n\nTasco however is not known for great optics. They are better know for cheap optics. \n\nYou did not mention what you wanted to use the telescope for. \n\nFor a decent spotting scope, select a Celestron Ultima 100 mm. \n\nAnd do not scimp on the tripod. \n\nFor a top of the line spotting scope, select a Swarovski. The best of the best. \n\nFor astronomical viewing you want something a tad larger. An 8 inch reflector.  \n\nCheck out the link to this one.
181006
I cannot tell you whether or not it has been done...\nBut I will never be truly "trapped" even with a mirror with a fairly high finish (aka 1-2 microns) there is still a loss every time it "bounces" off the mirror + if you do not do it in a vacuum there will be atomspheric losses as well.\nHenceforth if it is "trapped" it wouldn't stay there for long..
95368
No problem!  A parabola is a parabola.  The distance from the parabola to the focus is the same no matter the wavelength.  Your 3 dB beam width and antenna gain will, however, vary with wavelength.  The antenna gain (EIRP) is given as\n\nGmax = nu(pi D f/c)^2\n\nwhere nu is your antenna efficiency (0.5-0.8 is typical), D is the diameter of the antenna, f is your frequency, and c is the speed of light, 3*10^8 m/s\n\nYour 3 dB width (an approximation) is given by:\n\nTheta = 70(lambda/D) = 70(c/fD)\n\nlambda = wavelength, D = diameter of your dish, c = speed of light, f=frequency\n\nIn order to make this work, you will need multiple feeds, typically appropriate length dipoles tuned for each band, at the focus of the parabola.\n\nMake sense?
868776
We'll be watching at my school if it's not cloudy (the weather doesn't look good for the northeast US).  We don't have anything fancy, just an 8" Schmidt-Cass with a solar filter.  If we do get clouded/rained out, then we'll be watching a webcast, projected on the planetarium dome.