SHORT BLASTS
Roof
Porro
Shooting with both eyes open allows the
hunter to quickly acquire the target, see
potential hazards, and execute a proper
trigger pull.
Prism
Prism
Learn to Shoot with
Both Eyes Open
When the moment of truth comes and
that animal you’ve hunted so hard for
finally presents itself and you position
yourself behind the rifle and settle in
the scope, do you shut one eye and fo-
cus only through your dominant eye or
do you keep them both open? A com-
monly asked question is, what is the
preferred method?
As humans, our eyes are designed
to work together, so shutting one of
them while trying to accomplish a task
like shooting a target is really limiting
yourself. Closing one eye can lead to
quicker eye fatigue in the open eye, as
well a decrease in functions such as
depth perception, visual acuity, and bal-
ance. Additionally, our brain operates
through a cycle called the OODA loop
— Observe, Orient, Decide, Act. Keep-
ing one eye closed slows down this pro-
cess, as the brain is not receiving the full
slate of observations. While this is often
discussed in self-defense scenarios, it
is also a very useful concept in hunting
situations. Acquiring the target, seeing
potential hazards around it like other
deer or a steady crosswind, determining
if you can make the shot, and executing
a proper trigger pull can all be enhanced
with both eyes open.
Many of us grew up shooting with
one eye closed so this will not necessar-
ily come naturally to everyone. Practice
this during your dry firing drills before
heading to the range and eventually it
will become more habitual. This may
take some time, but in the end, the re-
sults will be well worth it.
KEVIN MADISON
18
WESTERN HUNTING JOURNAL
Objective
Lens
Objective
Lens
Path of Light
Path of Light
Porro Prism vs. Roof Prism:
Understanding Binocular Design
S
pend even a brief amount of time
flipping through the pages of cata-
logs or browsing the counters at the
local sporting goods store and you’ll
quickly find that the options and styles
of available binoculars are more plentiful
than jackrabbits in a Wyoming alfalfa field.
While most of us have a basic understand-
ing of things like objective size and magni-
fication, the details of the inner workings of
binocular design are less well known.
The most dramatic shift over the last de-
cade or so has been the surge in popularity
of straight barrel roof prism designs. In fact,
these styles are so plentiful it can actually
be hard to find traditional porro prism op-
tions. So, does this mean roof prisms are su-
perior to porro? It really boils down to how
you intend to use your binoculars, and how
much you are willing to spend.
Traditional porro prism binoculars are
what most of us cut our optics teeth on.
The easily identifiable offset barrel design
most commonly placed the large objective
lenses farther apart than the ocular eye-
pieces. Light enters the objective lens, is
reflected in a shape resembling the letter
Z between two prisms and then exits the
eye piece. Because all internal surfaces are
reflective, there is no light lost during the
reflective process. The resulting optical
quality is actually better than roof prism
designs; producing a high degree of con-
trast and images with great depth of field,
and with minimal eye strain. Because this
process is relatively simplistic, manufac-
turing costs are lower thus resulting in
cost savings to the consumer. The down-
side to porro prism models is the space
needed to properly configure the prisms
results in larger, bulkier, less comfortable
to hold overall binocular size, as well as
lower resistance to moisture and dust in-
trusion. Porro prism models are great for
applications where you don’t plan on car-
rying the binoculars for considerable time,
such as keeping a pair in your vehicle.
Roof prism binoculars have two major
drivers behind their popularity: compact
size and reduced weight, making them per-
fect for all day packing. The sleek straight
barrel design also produces a comfortable,
secure grip. Light entering a roof prism is
reflected in a more obscure circular path-
way between the prisms, and also reflected
more times than in porro prism construc-
tion. This requires very precise orientation
of the prisms. The prisms also require spe-
cialized reflective and phase correcting
coatings to maximize light transmission
and reduce chromatic aberrations that im-
pact image clarity and color transmission.
The precision of construction and coatings
necessary for premium performance dra-
matically increase manufacturing costs,
which is why top-quality roof prism binoc-
ulars carry hefty price tags.
As a general rule of thumb, if you are on
a budget, you can pick up a premium pair
of porro prism binoculars at around the
same price as an entry level roof prism. If
you choose to purchase a roof prism model,
the old mantra of “buy once, cry once” re-
ally does hold true. The best construction
does come at a premium price. But to better
understand all that goes into binocular con-
struction, a little research will go a long way.
ERIC MARTIN