Basic Photography Course

front of the lens. When you use more than one filter or

a particularly thick filter, you may end up with
vignetting. This results in the edges of the image being
cut off, particularly at wide apertures. When using
wide-angle lenses, you should use lens hoods and filters
designed for the particular lens in question.

Ultra-Wide-Angle Lenses

Many ultra-wide-angle, or short-focal-length,

lenses are known as fisheye lenses. These lenses have a

focal length of less than about 17mm (for a 35mm

camera). The ultra-wide-angle view of these lenses
results in image distortion. Straight lines appear curved
and curved Lines may appear straight.

The use of fisheye lenses makes objects appear to

diminish in size rapidly as the distance from the camera
increases and objects which are close to the camera

appear far apart.

Depth of field with a fisheye lens is very great. `They

often give depth of field that extends from only inches
in front of the lens to infinity so that focusing is not

necessary.

Rectilinear Lenses

A rectilinear lens, despite its wide angle, has normal

rectilinear corrections so straight subject lines are
straight in the image and there is no obvious distortion.
The width of objects close to the camera appears
emphasized because of the steep perspective produced

by a rectilinear lens.

Macro Lenses

A macro lens is used for closeup photography and

is a valuable lens for any imaging facility to have. These
lenses come in various focal lengths and are capable of
producing up to one half or even life-size 1:1 images.
For example, a 100mm macro lens produces a 1:1 image

just as a 50mm macro does. With a 100mm lens, you do

not have to get as close to the subject. This is especially
useful when you are taking pictures of live creatures or
doing closeup medical photography.

Normal Focal-Length Lenses

The standard or normal focal-length lens for a

35mm SLR camera is from about 40mm to 58mm (the
most common being 50mm). This focal length gives a
field of view roughly the same as that over which the
eye gives satisfactory sharpness-thus the name normal

Figure 1-35.Arrangement of lens elements in a telephoto lens.

focal length. With a normal lens, the angle of view and
the image size you see in the viewfinder are normal. That
is, you get much the same impression as you would get
if you look at the subject with one eye. Many Navy
photographers claim, however, that the wider angle of
view of a 35mm lens (for a 35mm camera) is preferable.
Others maintain that an 85mm focal length is better for
general use because it enables the picture space to be
filled more easily with subject matter.

A normal lens can be used for making pictures of

people if you do not get too close. When you fill the
frame with the face of the subject, you get image
distortion. It is better to stand farther back and include
the shoulders of the subject in the picture. This
eliminates distortion.

Telephoto Lenses

A lens with a focal length greater than about 58mm

for a 35mm camera is a long-focal-length lens. Most
modern, long-focal-length lenses are called telephoto

lenses because of their compact design. At one time,
long-focal-length lenses were essentially a lens at the
end of a long tube. A 500mm lens was spaced 500mm
from the film, and so on. However, by incorporating
other glass elements, the light passing through the lens
can be modified (fig. 1-35). This permits the lens barrel
to be physically shorter than the lens actual focal
length-an arrangement known as telephoto.

1-34

contents

Basic Photography Course

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DOFMaster for Windows On-line Depth of Field Calculator DOFMaster for Mobile Devices On-line Depth of Field Table Hyperfocal Distance Chart Articles FAQ Recommended Books Support Contact Links Home As an Amazon Associate I earn from qualifying purchases.	contents <- previous page next page -> front of the lens. When you use more than one filter or a particularly thick filter, you may end up with vignetting. This results in the edges of the image being cut off, particularly at wide apertures. When using wide-angle lenses, you should use lens hoods and filters designed for the particular lens in question. Ultra-Wide-Angle Lenses Many ultra-wide-angle, or short-focal-length, lenses are known as fisheye lenses. These lenses have a focal length of less than about 17mm (for a 35mm camera). The ultra-wide-angle view of these lenses results in image distortion. Straight lines appear curved and curved Lines may appear straight. The use of fisheye lenses makes objects appear to diminish in size rapidly as the distance from the camera increases and objects which are close to the camera appear far apart. Depth of field with a fisheye lens is very great. `They often give depth of field that extends from only inches in front of the lens to infinity so that focusing is not necessary. Rectilinear Lenses A rectilinear lens, despite its wide angle, has normal rectilinear corrections so straight subject lines are straight in the image and there is no obvious distortion. The width of objects close to the camera appears emphasized because of the steep perspective produced by a rectilinear lens. Macro Lenses A macro lens is used for closeup photography and is a valuable lens for any imaging facility to have. These lenses come in various focal lengths and are capable of producing up to one half or even life-size 1:1 images. For example, a 100mm macro lens produces a 1:1 image just as a 50mm macro does. With a 100mm lens, you do not have to get as close to the subject. This is especially useful when you are taking pictures of live creatures or doing closeup medical photography. Normal Focal-Length Lenses The standard or normal focal-length lens for a 35mm SLR camera is from about 40mm to 58mm (the most common being 50mm). This focal length gives a field of view roughly the same as that over which the eye gives satisfactory sharpness-thus the name normal Figure 1-35.Arrangement of lens elements in a telephoto lens. focal length. With a normal lens, the angle of view and the image size you see in the viewfinder are normal. That is, you get much the same impression as you would get if you look at the subject with one eye. Many Navy photographers claim, however, that the wider angle of view of a 35mm lens (for a 35mm camera) is preferable. Others maintain that an 85mm focal length is better for general use because it enables the picture space to be filled more easily with subject matter. A normal lens can be used for making pictures of people if you do not get too close. When you fill the frame with the face of the subject, you get image distortion. It is better to stand farther back and include the shoulders of the subject in the picture. This eliminates distortion. Telephoto Lenses A lens with a focal length greater than about 58mm for a 35mm camera is a long-focal-length lens. Most modern, long-focal-length lenses are called telephoto lenses because of their compact design. At one time, long-focal-length lenses were essentially a lens at the end of a long tube. A 500mm lens was spaced 500mm from the film, and so on. However, by incorporating other glass elements, the light passing through the lens can be modified (fig. 1-35). This permits the lens barrel to be physically shorter than the lens actual focal length-an arrangement known as telephoto. 1-34 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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