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RE: RE: What Should I Build Now?

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Posted by Anthony Kight on March 16, 2000 18:15:46 UTC

I did a proper focal length test outside using the sun. also the astronomy/physics instructor at my college helped me set up the test. I am quite sure it was done properly. You stated that the mirror must be just about flat. Actually the flatter the mirror, or more correctly the larger the radius the longer the focal length. This mirror will just about fit a basketball if it were not a parabolic shape. Given that the focal length of a sphere is aproximatly 1/2 the radius of the sphere then a mirror that just fits a basket ball would have a focal length of about 1/2 of the radius of the ball, or 1/4 the diamiter of the ball. in either case this mirror works out to about 3". I understand a type of camera can be built with this short of a focal length, however I am beginning to look at maybe going the other way and using it to build some sort of microscope device to teach my kids about magnification. I am still is search of a 6" to 10" mirror that I can use for my telescope. Thank You for any comments or help you can give me on this. Tony

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