Re: ATM f/D=6 why??

[Brand <huntb@ucs.orst.edu>]

> Now I realise that a larger f/D ratio would make the telescope tube a bit 
> unwieldy, but obviously f/D=6 seems to be the optimum compromise. could 
> somebody shed some light on this, sorry if this has been a FAQ but I just 
> could'nt find any answers.
jay,

I would calculate the length of telescope you want to work with. That is, 
if you are only 3 ft. tall, don't make an 8"f12 That would take a large 
ladder. I don't like ladders, especially in the dark. So, I choose 
f/d ratios that I don't have to climb onto, by choosing aperatures or 
focal distances that are smaller.

My first mirror was a 8" f7.1, but I was shootin' for f8. ;) So, if you 
build a scope that is f6, it'll be reasonably short, semi-'easy' to 
figure and build. If you are tall (5ft-6ft) I'd go with an f8.

Please tell me if this doesn't make sense, little sleep last night. :)

-brand

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