Canon Image Stabilizer Series - Manual (Page 7)

a 6.5˚ field-of-view appears to have a
65˚ range; qualifying it as a wide angle
instrument. The greater the apparent
angle-of-view, the easier it is for you to
pinpoint and track your subject. The
Canon binocular line offers models with
apparent angles-of-view that range from
45˚ to 67˚.
Differences in brightness
The brightness of an image is associated
with the amount of incidental light that
is reflected by the lens. Uncoated lenses
can reflect away as much as 8% of
incoming light per lens element —
resulting in a dim image. For this reason
Canon employs Super Spectra Multi
Coating to enhance brightness.
Since many things contribute to the
brightness of an image, be sure to
consider the following factors as you
compare binoculars:
Exit pupil diameter
The size of the image that emerges at
the binocular’s eyepiece impacts image
brightness. In dimly lit settings, a large
exit pupil, for example 4.2mm found on
the 10x42L IS WP, delivers brighter
results. For daytime viewing, binoculars
with exit pupil sizes between 2.5 and
3mm are often sufficient.
Objective element diameter
This refers to the front lens element
measured in mm. All things being equal,
the larger the lens in front of the
binocular, the more light it can take in
and the brighter the viewing image will
be. The 18x50 IS AW and 15x50 IS AW
have the largest objective lenses in
Canon’s binocular lineup.
Twilight coefficient
One difficulty with using traditional
numerical ratings to determine a
binocular’s suitability for low-light
viewing is that higher magnification
binoculars, even those with smaller exit
pupil size or “relative brightness” ratings,
can often reveal better detail in low light
because of their higher magnification.
Twilight Coefficient or Twilight Factor
accounts for the magnifying power of a
pair of binoculars, and can be a useful
rating—especially if viewing at dawn or
dusk, or deep shade viewing conditions.
Judging quality
When evaluating binoculars brands and
models, here are few things to look for:
Alignment
If the parallel tubes of the binocular are
out of alignment due to a manufacturing
defect or accident, you’ll see two similar
but separate images. There is no way to
repair this problem and it renders the
binocular virtually useless.
Color
Focus the binocular on a white object.
Check two things: first, that the white
object appears a faithful white tone
Canon’s Super Spectra Multi Coating
Narrow field- of-view
a. Real field-of-view: 6.5˚ b. Apparent
angle-of-view: 65˚ c. Field-of-view at
1,000 yards: 340.6 feet
Looking through a 10x42L IS WP binoculars
at a subject 1,000 yards away
Wide field- of-view
13
Find the binoculars that fit your needs.
Waterproof and all weather
Several models in the Canon binocular
line are waterproof or water-resistant.
Designed to be used outdoors and on the
water, these models are built to withstand
a broad range of conditions including
rain, humidity and more. The new Canon
10x42L IS WP offers Canon’s highest
standard of waterproof performance—it
can be completely submerged.
Lead-free optics
Canon uses environmentally friendly
lead-free glass in its optical systems.
This creates the high-quality
performance you demand from your
binocular while protecting the
environment from unnecessary harm.
The importance of objective
lens diameter
Binoculars are described by the power
of their magnification (18x, 15x, 12x,
etc.) combined with the diameter of their
objective lenses (50mm, 42mm, 36mm,
etc.) The greater the magnification power,
the larger your viewing subject will appear
in the objective lens as you look through
the binoculars.
For instance, if you use the 10x42L IS WP
to track a subject 100 yards away, it
appears to be the same size as a subject
located just 10 yards away seen without
binoculars. All things being equal, the
larger the diameter of the objective lens,
the more light it can admit for brighter,
more detailed images. So binoculars like
the 10x42L IS WP, 18x50 IS AW and
15x50 IS AW produce particularly bright,
clear images.
The key to Field-of-View
The field-of-view is the area you see when
you look through the binocular. The higher
the magnification power, the narrower the
field-of-view. The apparent angle-of-view
is the product of the magnification times
the real field-of-view. So in the case of the
10x42L IS WP, the 10x magnification with
100 yards away
with the naked
eye.
10 yards away with
the naked eye.
With a 10x magnification binocular,
the hot air balloon 100 yards away
will seem as if it were 10 yards away.
When bright....
When dark....
Viewer’s pupil
diameter is 3.0mm.
Pupil dilates
as wide as 7.0mm.