What are BAK-4 Prisms and why are they Important?
The optical quality of the prisms in a binocular are a major factor in the quality level of the images produced by the binocular. The majority of todays binocular prisms are made from borosilicate prisms (BK-7) or barium crown prisms (BAK-4). BAK-4 prisms are a much higher quality prism than BK-7. BAK-4 prisms produce much brighter images and sharper images towards the outside edges than the lower quality BK-7 prism.
