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Re: Building A Telescopes Questions

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Posted by Brandy Richardson/">Brandy Richardson on January 10, 2000 15:36:21 UTC

: : I have many ?'s

: : 1-What does f/6 for example mean and in what units are they measured. : F ratio is measured by the focal length over the primary diameter. It indicates how "fast" the system is. : : 2-What do you reccomend size wise for seeing lots of deep space object. Mirror-satigga and focal length and secondary mirror size. : Depends upon what your finances are. The larger, the more you can see. If you have the money, a mirror about 30" or so is as big as it : appears that you can go and get good images. Larger scopes that I have seen all seem to have something wrong with them that prevents them : from being good instruments and as I don't own them or have a long term access to them, I can't tell exactly what is wrong. The bottom end : is that I haven't seen anything larger perform well. Satigga (I think that you mean sagitta) is a function of focal length and size of the : mirror so you basically said two things at once and the secondary mirror size depends upon what you are doing. I suggest that you look for : pages of telescopes and find out what they are doing. There are lots of those pages. Just search.

: : 3-How do you grind the primary mirror. : Depends upon the size. smaller mirrors (under 12") are easily ground by hand and larger ones it usually makes sense to make a grinding machine : for the work as the push needed will quickly tire even Mr. Atlas and it gets to a point where it is impossible. : : 4-Can you make homade eyepieces or should you by them. : Buy the EP's. Modern EP's have 4 or more pieces of glass in them and the recipies for them are difficult for the beginner. : : 5-Does the secondary mirror size matter. : Yep. : : 6-How long should the tube be. : Long enough to hold the optics design at a minimum. The diameter is almost more important as that is one of the things that determines the field : of view of the instrument. Also don't forget baffling the tube. It is important for good images and a large field of view.

: Have Fun and Keep Looking Up!!!

: P.S. Remember that you only have to press the Send button to send a post!

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