Erfle eyepiece

Erfle eyepiece

(erf -lĕ) See eyepiece.
References in periodicals archive ?
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.
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.
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.
Surplus binoculars typically contain wide-field Erfle eyepieces that are a cut above the kind you're apt to find on most any low-end commercial telescope.