Premium BAK4 & FMC Lens Material

• BAK4 costs more, and it is a high density glass of better optical quality than BK-7.
• The design of the prisms can affect the quality of the exit pupil, especially obvious at night. BAK4 has a perfectly round exit pupil; BAK-7 has a squared-off, non-circular exit pupil with shaded (blurred) edges.
• “Fully Multi-Coated” (FMC) optics is ideal as ALL the glass surfaces have received Multiple layers of anti-reflection coatings which usually results in a transmission level of approx. 99.6%.