I want to build a telescope and was wondering if I could use this mirror.?

Question

http://www.amazon.com/gp/product/images/B000UOHCYS/sr=8-5/qid=1209958432/ref=dp_image_0?ie=UTF8&n=3760901&s=hpc&qid=1209958432&sr=8-5.
It has a 10x magnification. What I'm hoping to do is first see some nice detail on the moon and maybe see a bunch of things I have never seen before (planets). I already have an eyepiece from an old pair of binoculars that I can use along with a small rectangular mirror and plan to build the tube out some strips of wood and fiber glass.
Would the mirror be worth trying? Any other alternatives to a mirror that's not too expensive? Less than $60. Homemade or premade.

Answer 1

No, I don't think so. These cosmetic mirrors have a very poor figure and have their rear surface silvered, rather than the front surface which is required for astronomy. It would give you double images, if you could get it to focus at all. The requirements for even a simple Newtonian telescope for astronomical use are much higher. The least expensive telescope which I recommend is the Orion StarBlast at $180:

http://www.telescope.com/control/product/~category_id=dobsonians/~pcategory=telescopes/~product_id=09814



Orion has their most basic 60mm refractor on sale today only for $75, which might be within your budget. Strangely, it's cheaper to buy a complete telescope nowadays than to try to buy parts and assemble one yourself.

Answer 2

For a good astronomical telescope, the mirror should be accurate to within at least a quarter of a wavelength of light, preferably a tenth. Since the wavelength of visible light is less than a micron (one millionth of a meter), you will not get this accuracy unless the mirror is ground specifically for a telescope.



Next, mirrors for telescopes are silvered at the front. Mirrors for most household tasks are mirrored at the back to protect the silvering. This means that you would get double images even if the mirror were ground accurately enough.



Finally, the focal length of that mirror is small enough that you would not be able to make a telescope out of it even if it were ground accurately enough and silvered at the front. Think about how close you have to be to a cosmetic mirror to see the image. Now imagine trying to get a secondary mirror and eyepiece into that space.



I would suggest that you go to a local astronomy club. There is usually someone there that has made their own telescope mirror and can show you how. If you do it right, you can even use the bottom of a coke can, but you have to know what you are doing. Alternatively, look up 'mirror grinding' online.

Answer 3

For terrestrial observing (things on the ground), you *might* be able to make something serviceable.



For astronomy, don't try it.



There are several things that make this mirror inappropriate for astronomy:

1. All household mirrors are "second surface" mirrors, which means that the reflective surface is on the back of the glass surface. (Try to touch the image of your own finger in a household mirror, and you will see that you can't, because the glass gets in the way.) But that piece of glass causes an extra little reflection itself, which causes a faint "ghost" image when you're looking at a star at night. So astronomical mirrors are "first surface" mirrors, where the reflective material is on the front of the glass instead of the back.



2. This mirror has a sharp curvature, which means it has a very short focal ratio. That means that you will need a very large secondary mirror, so large that it will block much of the incoming light. Astronomical mirrors have longer focal ratios to avoid this problem.



3. A mirror like this is ground to be a sphere, which is cheap and easy to do. But a spherical mirror won't focus properly, especially when it's got a short focal ratio like this. Astronomical telescopes either use a parabolic mirror, or a corrector plate in front, to avoid this problem.

Answer 4

you would possibly want to wish to study your community library as they could have some books in this subject. you may also attempt right here on Google. merely form in some thing like "making a telescope" interior the search engine.

Answer 5

The optical quality of that mirror would not

be consistant with a telescopes requirements.