开云体育

Hi Richard,

Never used a UO binoviewer but this is what Todd Gross says about them:
1. Microscope-head style binoviewers (Celestron-Orion -University Optics):
Adapted from Microscope heads, small prisms with limited clear aperture, 45
degree angle rather than straight through or 90 degree angle. Most will plug
right into a 1.25" star diagonal, some like Orion's screw right onto the
back of a Schmidt - Cassegrain scope. You can adapt Celestron's binoviewer
to fit onto a schmidt-cassegrain like that using their standard visual back.

The disadvantage of this binoviewer is that you cannot easily use eyepieces
much over 18 or 20mm before you will see significant vignetting. The general
light throughput is also not quite as good, and the 45 degree angle can be
somewhat distracting. You cannot easily use these at all on reflectors.

The other major disadvantage is the problem with focus shift as you adjust
the two eyepieces (push-pull) for the different distances required for
different sets of eyes. In fact, even with just ONE user, you sometimes have
to change this interpupilary distance to accommodate different sets of
eyepieces, and here again you will need to refocus every step of the way as
you adjust the width between the eyepieces.

The advantage of this style is the price, they tend to run around $500-$600
or so new, and a bit less second hand. (Orion's list is $649) They come in
and out of availability and when I checked several months ago, the Celestron
unit was not available, the Orion unit was.

The other advantage is that on the Moon and planets at high power, you seem
to be able to get as good performance, or just about anyway, as the more
expensive units. Like all binoviewers, it takes a lot of focus travel to be
able to accommodate them, see further down in this article for details.