ANTARES 8.5-12mm SWEERS-WALER SWA - VARIABLE FOCAL LENGTH EYEPIECE (Preowned)

This item is preowned, in good condition.

ANTARES 8.5-12mm SWA - VARIABLE FOCAL LENGTH EYEPIECE (Preowned)

The eyepiece WALER part of the name stands for Wide Angle Long Eye Relief, and the concept is a wide-field (over 70 degrees) fairly well corrected eyepiece. The variable focal length comes from the introduction of the ability to move the field-flattening “Smyth” lens in the front of the eyepiece farther away from the other elements. As such, this movement acts somewhat like a variable power Barlow to raise or lower the magnification while still providing much of the field flattening effect which is needed for these better-corrected wide-field designs.

Dimensions: 6 to 8 inches (152 mm to 203 mm) long x 2.5 inches (64 mm) wide.

Focuser Barrel Size: 1.25 inch standard (threaded for filters).

Weight: 1.32 lbs (600 grams)

Number of Elements: 8

Focal Length Stops: 8.5mm, 9mm, 9.5mm, 10mm, 10.6mm, 11.3mm and 12mm.

Measured Apparent Field of View: 81.4 degrees (constant at all focal lengths).

Eye Relief: approx. 11 mm.

Effective Field Stop Diameters: 14.9 mm at the 12mm focal length setting,

13.4 mm at the 10mm focal length setting,

11.5 mm at the 8.5mm focal length setting.