BOB 860409 Instrucciones De Uso página 13

The field of vision is that part of your surroundings that can be seen through
the binoculars and is expressed as an angle or distance at a range of 1.000
meters. The higher the magnification the smaller the field of vision.
Bk-7 glass. The porro prisms used in your binoculars are made of barium
crown glass (Bk-7). This glass gives you an image with good contrast.
Fully coated lens. To increase light permeability in your binoculars an
aluminium coating was steamed onto each lens surface in a high vacuum.
This coating is visible on each lens as a blue layer and yields a very bright
and extremely sharp image.
Cross-section
of your
binoculars
13 13
(5-lens system)
Bk-7
prisms
Fully coated
objective lens
G
B