The lens has more than 120% the light gathering capability of a 60mm objective lens.
PROMINAR models TSN-663 and TSN-664 using XD-Fluorite glass for the objective lens. This reduces chromatic aberration to a minimum.
All lenses, prisms, and dustproof glass are fully multicoated, ensuring sharp images and a clear visual range.
The housing is waterproof to JIS protection class 7 and filled with dry nitrogen gas to prevent the lens from fogging.
JIS 7 = Japanese Industrial Standard / class 7 = Protected against the effects of temporary immersion in water.