JVN wrote:
"Another way to say it is that the exit pupil of the scope will not
exceed the entrance pupil of your eye. This points out another issue
with too-big exit pupil: the shadow of the secondary becomes
bothersome; you'll have a vague shadow moving around interfering with
part of the field of view. In some cases you can find a position for
which the field of view is unobstructed. "
I prefer using a Daystar solar filter instead of Coronado's for this same reason. Coronado's design has an obstruction of up to 24% which I find very bothersome when viewing the sun. It feels like something's poking me in the eye! Daystar's design is unobstructed. Although the views through Coronado's units are very nice, there is a compromise (though it's effects are probably not significant to the casual observer).
When viewing the sun, the eye's pupil is generally at it's smallest and the telescope's exit pupil can be much larger. I prefer a large exit pupil for this application because it's like looking through a hole in a wall. With a larger "hole", I don't have to keep my eye's pupil perfectly in the plane of the scope's exit pupil. This is much more comfortable for extended viewing of activity on my star of choice.
Received on Sat Jul 31 13:38:54 2004