Is my 75mm hand mirror suitable for a dobsonian telescope?
Altair asked:
I have seen wesites on how to build your own dobsonian telescope. I know that the primary mirrors of most dobsonian telescopes have a focal length ranging from 1000mm to 1200mm. But I do not know whether my hand mirror fits into this catagory. I don’t mind having a telescope with a small aperture.
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I have seen wesites on how to build your own dobsonian telescope. I know that the primary mirrors of most dobsonian telescopes have a focal length ranging from 1000mm to 1200mm. But I do not know whether my hand mirror fits into this catagory. I don’t mind having a telescope with a small aperture.
February 17th, 2010 at 4:44 am
Hi Altair, I am not sure what you mean by a “hand mirror”. If you mean a mirror that you use for checking your appearance, then even if id was curved, the curvature would not be sufficiently consistent to be able to use it in a telescope. Mez
February 19th, 2010 at 7:11 am
No. Too small, short focal ratio, spherical surface, second surface coating, inaccurate figuring and polishing.
Instead: Geoff G
February 20th, 2010 at 1:16 am
If you mean a hand/makeup/shaving mirror, then you are not the first person to try this. The first attempt to build a reflecting telescope by Niccolò Zucchi in 1616 was him trying to see an image made by one of these mirrors. It didn’t work because it turns out a mirror has to have a curve that is 4 times more accurate than a lens. So no… won’t work.
Have a look at for Zucchi’s story. R S