1.
1
Features and Benefits of Sport Optics Coatings
Bill Mooney of Kruger Optical, Inc
Lens coatings can play a major role in sport optics performance. An un‐coated lens can reflect 4
to 5% of the light coming into the optic. Most binoculars and rifle scopes have many lenses
inside the body. If a sport optic was produced without any coatings, the brilliance and clarity of
the image would be very poor.
Higher‐end products use better quality lenses and coatings to achieve brightness and clarity of
the image you see. Coatings are an important factor determining the price of a product, as well
as performance. Coating types include:
C‐Coated optics. Single layer coating on at least the outside lenses. Visible system transmission:
65‐75%
FC‐Fully coated optics. Single layer coating on all lens and prism surfaces. Visible system
transmission: 70‐80%.
MC‐Multi‐coated optics. Multiple coating layers on all external surfaces; single layer on internal
surfaces. Visible system transmission: 75‐85%.
FMC‐Fully multi‐coated optics. Multiple coating layers on all surfaces. Visible system
transmission: 80‐90%.
BBAR‐Broadband multi‐layer coating. All surfaces receive high performance multi‐layer
coating. Visible system transmission: 85‐93%.
Optical glass: Lenses and prisms made from high quality optical glass deliver better image
sharpness than lower‐grade glass. Prisms made from BaK‐4 glass are considered best for image
brightness. BK‐7 prisms also perform well.
Prism types: Modern binoculars contain prisms to correct image orientation; without them,
objects would appear upside down. Most binoculars are made with either porro prisms or roof
prisms. Porro prisms give binoculars their traditional offset shape, with the objective lenses set
wider than the eyepieces. Roof prisms give binoculars a straight appearance, with parallel
barrels. Porro prisms usually offer the best optics for the price, but they can be heavy and
bulky. Roof prisms have a more compact, streamlined shape. Often, prism style is a matter of
personal preference.
Eye relief: Eye relief refers to the distance between the eyepiece and the spot where the full
image is most comfortably viewed (where your eyes go). Customers who want to use their
products while wearing eyeglasses (or sunglasses) should look for long eye relief (at least

2.
2
16mm).
Eyecups: Many binoculars are equipped with either fold‐down rubber eyecups or twist‐up
eyecups, so they can be comfortably used with or without eyeglasses.
Waterproofing: Products intended for outdoor or marine use are often water resistant or
waterproof. Waterproof products are O‐ring sealed and filled with dry nitrogen or argon to
prevent fogging. Waterproof products are made to withstand prolonged submersion. Water
resistant products are designed to withstand wet weather, but not submersion.
Shock proofing: Shockproof products have been ruggedized to survive being dropped or, in the
case of a riflescope, to hold a point of aim after rifle discharge.
Field of view: Field of view can be measured in degrees or as a number of feet that can be seen
at 1,000 yards. Lower magnification products usually have larger fields of view. Some products
are specially designed to have a wide field of view.
Close focus: Close focus refers to how close an object can be while still remaining in focus.
Being able to focus on nearby objects is important for such activities as bird watching and
wildlife viewing.
Windage and elevation: These adjustments pivot a riflescope's erector system to place the
reticle in line with the bullet impact point. Adjustments are typically in ? minute intervals or ?"
at 100 yards.
Other factors: Optics products should be rugged enough to withstand their intended use.
Products should also look good and feel comfortable with prolonged use. Rubber armor
housing helps prevent heat transfer, making products comfortable to handle in cold conditions.
Quality binoculars have diopter adjustments, so users can adjust for vision differences between
their two eyes.
Feel free to contact me if you have any other questions.
Thanks,
Bill Mooney
Marketing and Business Development Director
BillM@krugeroptical.com
6955 SW Sandburg St., Tigard, OR 97223
Phone: 541‐549‐0770 Ext. 274 Fax: 541‐549‐0769
www.KrugerOptical.com