Re: eye pieces

Jan Owen <janowen1@xxxxxxx> wrote:

In fact, I noted that Margo mentioned that her scope was 200mm... Yet when
I went to her scope manufacturer's website, THEY list it's aperture at
203mm. Then it says the focal length is 1200, which, of all the ones
they've made, only a relatively few are EXACTLY 1200mm in focal length...
So, we shouldn't really spend a lot of time using the manufacturer's
specification sheets to draw multi-decimal-place conclusions using them...

Hi, Jan and Steve and all.

First, please let me agree with you and Steve that in practice,
the tolerances or variations that attach to a spec like "200mm f/6"
might be greater than the theoretical distinction between that and
"203mm f/5.91," for example.

Just to clarify the situation about the stated specs for my scope.
On the Web, I've also seen 203mm/1200mm; but the printed information
on the OTA and also the manual say 200mm/1200mm. Given the inevitable
variations in practice, maybe inconsistent specs for this scope
actually could be considered a representation of some of the likely
variations <grin>.

Jan and Steve, your cautions about doing calculations to an unrealistic
number of significant digits are, of course, right on point! Maybe the
main reason I tend to like using the 200mm/1200mm figures is that this
often leads to nice round numbers for magnification or exit pupil or
the like <grin>.

Most appreciatively,

Margo Schulter
mschulter@xxxxxxxxxx
Lat. 38.566 Long. -121.430

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