ATM 75mm 3" or 100mm 4" eyepieces

[K1JJ@aol.com]

Hi!

I am looking for a commercial, military or even home made 75mm 3" eyepiece
and
a 100mm 4" unit. The diameters  of  3" and 4" respectively must be the
minimum, though
the 75mm and 100mm specs can vary somewhat.

Otherwise...Does anyone know of a source of these or way to build them? 

I am working with a 22" F8.5  Newtonian  with a universal size focuser holder
clear aperature to four inches, and want a couple of lower power views for
enjoyment....A 55mm yields 83X,  which is a 6.47 exit pupil....The lowest
power I presently have now.

A  75mm eyepiece  would yield  61X, with exit pupil of  8.83mm

A  100mm eyepiece would yield 46X, with exit pupil of 11.7mm 

I realize that any exit pupil over about 7mm is useless for increased
brightness,  (thats about my pupil size) but does anyone have an idea what
the view looks like thru a 3" or 4" wide eyepiece? Does your eye have to move
around to see the complete image? Lets assume the eyepiece is a common Erfle
type, not a wide field Nagler Type II style.

Maybe there's a better way to lower the magnification of the scope w/o
vignetting the field. I once tried a borrowed 2" wide  89mm eyepiece and of
course the field was simply the same as a 55mm, but smaller due to
vignetting.

Thanks.

Tom Cathey
K1JJ@AOL.com