My best roof prism and Erfle eyepiece
came from a gunsight bought for five pounds.
"Decades ago I built an 8 inch f/6 that I used with an oversized 38-mm Erfle eyepiece
to get a 2[degrees] field of view," Mel recalls.
But I also had the luxury of uncompromising optics (something that Shaw didn't enjoy a quarter century ago with his achromatic refractor and Erfle eyepiece
The camera was equipped with an old-fashioned Erfle eyepiece
for centering the telescope on its target, and my target that night was the magnificent globular cluster 47 Tucanae.
Once at a star party I used a 90-mm refractor with a 25x Erfle eyepiece
to show them both.
The telescope - a 10-inch f/6.5 Newtonian reflector with a 16-millimeter wide-angle Erfle eyepiece
- is positioned about 4 feet from the screen.
If you choose to purchase oculars and are not as fanatical about wide apparent field as I am, Erfle eyepieces
with 65[degrees] fields and focal lengths in the 25- to 16-mm range will provide nice views at a reasonable price.