From: "bruce_piano" <bruce_piano@...>
> I didn't have a distortion problem with this eyepiece. The problem was
> when I looked in the eyepiece I would see some sort of reflection or
> black background in part of the view.

Hmmm ... One problem that has plagued wide field oculars is the "kidney
bean" effect. Depending on where you place your eye, you'll see a black spot
floating in the field. These oculars tend to have long eye relief, meaning
you have to position your eye farther back from them. When you try to move
your eye closer to the eyepiece in order to see the edge of the field, parts
of the field between the center and the edge are cut off, because part of
the converging light beam misses the eye's pupil. That might be what you're
describing.

> Perhaps this is light loss?

No, light loss would not be that obvious. The image would just not be as
bright as it would be in a slower scope.

Also, a correction: after I sent my first response, I realized that the
distortion in my 40mm ocular did not manifest itself as elongated stars, but
rather as bloated star images.

Jack Kramer
Lily Lake, Illinois