So, won't a 2" eyepiece spread the photons over a wider area and, therefore,
appear less biright than a 1"?

Dark Helmet




"Bill Nunnelee" wrote in message
hlink.net...
Both formats use the entire objective, but the 2-inch eyepiece will "see"
a
larger portion of the focal plane. If this sounds contradictory, keep in
mind that photons from a celestial object are still traveling along
parallel
paths when they encounter the objective. The objective changes their
direction so they form an image at the focal plane. Photons that end up
near the edge of an eyepiece's field of view came from all regions of the
objective, not just its edge.



"Bruce W...1" wrote in message
...
Does a 1.25" eyepiece not use as much of the objective lens as a 2"
eyepiece?

All tubes have a focal length at which there is a focused image. If a
smaller eyepiece captures less of this focal plane than a larger
eyepiece then there is loss.

I'm no lens expert but it seems that a larger eyepiece would capture
more of the focal plane. A smaller eyepiece wastes some of the focal
plane.

Is this true or does a smaller eyepiece use as much of the objective
lens as a larger eyepiece?

Thanks for your help.