On 13 Aug 2004 00:28:39 GMT, (Jon Isaacs) wrote:

The topic at hand, the ED-100.

The last thread about this scope got badly off track and I am hoping to start
anew and this time I hope we can stick to considering the ED-100 and just where
it might fit into the scheme of things.

My thinking...

One can judge a scope based on the design parameters and in so doing an 4 inch
F9 with an ED objective is not something that appeals to me at first glance.
My initial reaction to this scope was, too slow, too long....

I had guessed (and posted several times), based on the ED-80, that any 100mm ED
scope from Orion would be about F9.4, not the 100mm, F6-7 scope that everyone
dreams of.

But in reality the 900mm focal length is not as bad as it sounds, in fact it is
not bad at all. When making the field of view calculation for the terrestial
section, I realized this scope can give some nice widefield views, in fact,
this scope has about the same capability because of the 2 inch focuser as a
500mm FL scope with a 1.25 inch focuser.

Upin the ante? That seems to be the perfect deal for this class of
refractor. 100mm at f9 and color correction is a long scope. 900
mm!! YUK! Anything over 800mm is too bulky.