Quote:
Originally Posted by janoskiss
Another thing to keep in mind is that the f.l. and hence the f-ratio of a Cassegrain is not fixed and depends on how far the EP is placed from the back. A 2" diagonal will slow it down some. So e.g. instead of 20mm you might want to go with 22-24mm. For same reason, you might also find that the 2x powermate is greater than 2x.
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Hi
I never realised this. Thanks for that information. Do you know how i can calculate the actual focal length of the scope with a 2 inch diagonal. Also i am thinking of a Crayford focuser which may slow it even more?
Thanks for all your replies
