Brochure

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ANGLE OF VIEW AND FOCAL LENGTH
84.1° 24mm 75.4° 28mm 46.8° 50mm 34.3° 70mm 23.3° 105mm
18.2° 135mm 12.3° 200mm 8.2° 300mm 5° 500mm 3.1° 800mm
FISHEYE 180° 8mm FISHEYE 180° 15mm 122° 12mm 103.7° 17mm 94.5° 20mm
PRINCIPLES OF THE LENS
What you should know to choose the right lens for your needs.
Angle of view
Angle of view is determined by the focal length of the
lens and the size of the image (sensor or lm format)
frame. With a given image size, changing the focal
length will change the area of the scene that appears
in the photographic image. Expressed in degrees,
this area of the scene is the angle of view. The longer
the focal length, the smaller the angle of view and
the greater the image magnication.
F-number
The aperture controls how much light can be gath-
ered by the lens. The F-number (F2.8, F4, F5.6, etc.)
is the ratio of the focal length to the entrance pupil
diameter. The lower the F-number, the brighter the
lens; the higher the F-number, the darker the lens.
The benets of a low F-number include the ability to
use higher shutter speeds, excellent bokeh effects,
and a bright viewnder image.
Perspective
Changing the focal length of the lens changes the
apparent distance in an image between the subject
and its background. This optical effect is called per-
spective. For example, a wide-angle lens causes the
background to seem far away and vast, emphasizing
the distance between it and the subject. In contrast,
a telephoto lens with a long focal length will cause
the background to appear close to the subject, de-
emphasizing perspective. Further, a wide-angle lens
can bring the surroundings of the subject into the
shot, while a telephoto lens can effectively isolate
the subject. By leveraging the power of perspective
in this way, one may greatly increase the range of
photographic expression.
Depth of eld
When you focus on a subject, some objects in front of
and behind the subject will also be in focus. “Depth
of eld” refers to the depth of this foreground-back-
ground distance. A smaller lens aperture (higher
F-number) increases depth of field, bringing more
F2.8
F22
foreground and background into focus. A larger ap-
erture (lower F-number) isolates your subject with
a blurred bokeh foreground and background. Focal
length is also a factor. Telephoto lenses have less
depth of eld, whereas wide-angle lenses have more.
Minimum focusing distance
The distance between the lm surface or image sen-
sor surface of an SLR or mirrorless camera and the
subject is known as the shooting distance. The short-
est shooting distance at which the camera can focus
on the subject is the minimum focusing distance.
Working distance
The distance between the front of the lens and the
subject.
Magnication ratio
The ratio of the size of the impression of a subject
captured on the image sensor or film surface to the
actual size of the subject. For example, when a 4cm
long subject appears as 1cm long on the image sensor
or lm surface, the magnication is described as 1:4.
If it appeared as 4cm long on the image sensor or lm
surface, the magnification would be 1:1. The maxi-
mum magnication ratio shown in the main specica-
tions describes the largest possible magnication of
the subject by that particular lens.