Quote:
Originally Posted by Mountain_Wanderer
Thanks mate. Can anyone tell me what the focal ratio is on this scope? Is it good? What is a decent focal ration to accomidate the best of both worlds?
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f6.3
I read this once in one of the old ATM books possibly by Albert G. Ingalls (Willman-Bell) many years ago. It is the best of both worlds, one being the rich field telescope (RFT) world and the other world being a telescope that is longer for greater power and being kinder on more simple eyepiece designs. Of course today coma correctors are more common as are much shorter and faster telescopes and of course higher quality more complex eyepieces.
Do not be too concerned about a particular f ratio. Anything from f5 to f6 is great for a typical Newtonian. f4.5 is OK but does benefit greatly from a coma corrector. f7 to f8 is good to but the optics get long in the larger diameters.