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Introduction
Wide angle lenses have become very popular in
recent years, and they have been getting wider. In the 1980s, the 35mm
lens is considered to be a wide focal length, and the 24mm to be extreme
wide. Today, with modern lens designs, focal lengths as wide as 17mm are
becoming more and more common. As we become used to wide-angle images,
manufacturers are offering wider angles to allow us to create images which
look "wide".
With modern lens-manufacture techniques such as
aspherical lens elements and floating-lens construction, wide-angle lenses
are getting better and cheaper to produce. Today, marque and independent
lens makers all offer a ultra-wide angle zoom with focal lengths of 17-35mm
or 20-35mm. The quality of such lenses are so good, they are un-imaginable
just a decade ago.
However, the wider the lenses become, the more
difficult it is to use them effectively. Issues such as distortions, flare
and empty spaces taunt the inexperienced users of wide-angle lenses. I
will discuss the various issues that users must take into account, to shoot
effectively with wide-angle lenses.
Exposure problems
Because wide-angle lenses "see" so much of the
scene, they might include in too much of the sky. This leads the camera
meter to believe that the scene is brightly lit, and thus result in underexposure
of the final image.
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The image above illustrates a wide-angle image
which included a large area of sky. Photographers must learn to recognize
situations where the camera might be fooled by the large areas of brightness
into underexposure. When you know that the camera is being fooled, point
the camera down to take a reading without the sky, and lock that exposure
for shooting (recommended method), or manually compensate for the sky.
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Large areas of sky
may mislead camera meter to underexpose
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Depth of field is extensive
Wide angle lenses offer extensive depth-of-field,
which photographers should utilize to their advantage. By stopping down
a couple of stops, you can improve the quality of the optics ( to be discussed
later) and increase the depth of field to ensure that the image is pin-sharp
from the foreground to the background.
Tip:
The depth of field (sharpness) is not distributed
evenly throughout the image. If you cannot stop down sufficiently, try
focusing into 1/3 of the scene (from the foreground) to maximize the depth
of field. Whenever possible, use the depth-of-field preview on the camera
to check your shaprness zones. |
Use the extensive depth of
field to ensure
sharpness from front to back
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I love your curves, baby
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Wide angle lenses accentuate curves very well,
so use this to your advantage! The image on the left shows how I exaggerated
the curves of the building on the right by tilting the lens upwards, to
make the curve more bent than it really is, making the image more dynamic,
and to act as a frame for the image to balance off with the building on
the left side. |
Dynamic diagonals
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Tiltiing lens upwards creates
converging diagonals
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Wide-angle lenses exaggerate
diagonal composition
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When the wide-angle lens is tilted upwards or
downwards, it creates converging lines. This means that lines which are
really parallel (such as the lines of the sides of buildings) converge
towards each other. Although this may make the object look deformed, it
also creates a very dynamic image. For example, by shooting from a low
angle, I made the building (top, left) more funky and dynamic by exaggerating
the converging lines and choosing very simple composition and strong colours.
The image on the right shows a corridor with parallel beams, which I turned
to my advantage by shooting it diagonally to create a dynamic image. The
use of a wide-angle lens gave me more apparent depth-of-field, which I
mamixmized by stopping down a couple of stops.
Corner distortions
| Because the wide-angle lens has to compress a
wider angle of field onto the film (compared to a telephoto lens), there
is some inevitable stretching of objects at the edges. This is an optical
property of wide-angle lenses, and there is nothing much you can do about
it. Observe the lower left corner of the image, and you will find that
the metal corner of the window looks stretched out of trhe frame.
The most evident stretching occurs at the corners,
and you can overcome this effect by trying not to place subjects in the
corner. |
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Vignetting
Because wide-angle lenses cover such a wide angle
of view, they are more likely than other types of lenses to "see" objects
not intended to be included in the image. The wide angle of view means
that you have to be careful about what you put in front of your lens. If
you put filters or lenshoods which are too thick, they will intrude into
the image area, and cause darkening around the edges of your prints.
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This diagram will illustrate the concept of vignetting.
In a telephoto lens, the angle of view (what the
lens "sees") is quite narrow. As a result, a long lenshood will not be
seen in the final image. However, a wide angle lens (above,left ) will
have a wider angle of view. The lenshood intrudes into the image area,
causing vignetting to occur.
Tip:
When using wide-angles, use thin filters and/or
avoid stacking more than one filter. Remove any skylight or protective
filters if you need to use other filters. In addition, use short lenshoods
with wideangle lenses. |
| This is a simulated image of vignetting caused
by thick filters or lenshoods. The corners of the image are darkened, because
the light path is blocked. If you see such darkening of the corners in
your image, the problem is usually vignetting. Try removing the filters
or use a narrower lenshood to solve the problem.
Tip:
Vignetting can also happen even though you do
not use any filters or lenshood. This is due to the light falloff of lenses,
which is especially evident when the lens is used wide-open. You can reduce
such light fall-off by stopping down your lenses a couple of stop. |
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Shutter speeds
Because of the focal length, the same image is
magnified less in a wide-angle image compared to a telephoto image of the
same scene. As such, any image blurring due to camera shake is less obvious.
This lead to the creation of the guideline that the minimum handheld shutter
speed should be the reciprocal of the focal length. For example, I can
safely handhold a 105mm lens at 1/125th sec, but I can handhold a 35mm
lens at 1/30th sec.
You might think that this allows you to get away
with slower shutter speeds and greater depth of field, or to use a slower
film. This may be true if you are restricting yourself to 4R prints. If
you intend to enlarge your images to a large size, the image may be soft
due to camera shake which you did not detect at small image sizes. So while
you can still apply the rule-of-thumb about slower minimum shutter speeds
with wider lenses, you have to make sure that you do not take this for
granted and ignore the basic rules of holding the camera steadily!
Aspherical elements
Image from Nikon lens catalog |
Most lens elements are spherical, which means
that they are manufactured with a "spherical" surface. However, in a wide
angle lens, the extreme angle of view makes it difficult to correct for
coma and oher lens abberations. This means that when shot wide open, some
points of light at the edges of the image will not be rendered sharp on
the image, because the spherical design is not effective to focus the entire
image. Why is this so? The spherical design bends all the light equally
to focus on the plane of focus. But in an extreme wide-angle, the edges
must be bent slightly less to fall on the same plane of focus.
Because the aspherical lens element is manufactured
with differing amount of curves, it can selectively bend the light waves
at different areas differently. This allows the lens to correct the difference
in focus mroe efficiently, reducing the lens distortions due to coma (where
points of light gets distorted at the edges, especially when the lens is
shot wide open).
When choosing a wide-angle lens (anything with
a focal length 28mm or less), try to get a modern lens with aspherical
lens element. |
Flare control
Because it is so wide, a wide-angle lens is more
likely to take in a source of light in the image area, leading to flare.
If source of light is in the image, either recompose so that the source
of light is excluded or stop down to reduce the flare. If the source of
light is just outside the image area and striking the front of the lens,
use a lens hood or your hands. Remove all filters if the flare is bad.
Use of multi-coated filters are a great help.
Leading composition to the background/subject
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When you have such a huge expense of area in
the foreground and background, you often need a guiding line in the image
to "lead" the viewers eye from the foreground to the background, preventing
the viewer's eyes from straying about. This technique is known as "leading",
and it can be accomplished by using obvious lines (such as the paths in
the field) or invisible lines (such as hands leading up to a face in the
portrait). Effective use of leading technique creates a image where the
viewer feels easy looking at the picture, rather than scanning the entire
image without a guidance. |
Panoramic trick (when there is no foreground)
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Sometimes it is just impossible to create foreground
interest. In that case, shoot and create a panorama by slicing off the
top and bottom of the image! Use the center of the image area to reduce
distortion. |
Near-far technique
| Remember what I said about extensive depth of
field of wide-angle lenses?
You can use the deep depth-of-field to your advantage,
when using the near-far technique to create foreground and background interest.
Sometimes, a scene presents itself with both interesting foreground and
background, and both are related to each other. To bring out both the foreground
and background, the use of a wide-angle lens is ideal. Use a viewpoint
where you can combine the foreground and background in the same scene,
and stop down the lens to create sufficient depth-of-field.
Tip:
When shooting a scene which requires extensive
depth of field, try not to stop down the lens to the smallest f-stop, because
diffraction might set in and you may get soft images as a result. Instead,
only stop down to what you need to get the sharp zone of focus, and use
the depth-of-field preview to check the zone. You might also like to use
the thirds focusing rule (focus 1/3 into the scene) and the hyperfocal
technique to achieve the required depth of field.
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"In-the-scene" look
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Because the wide-angle lens takes in so much
of the surroundings, it emulates the human's eye perspective in terms of
angle-of-view. A neat trick when using the wide-angle lens is to shoot
it at eye-level in a scene, and create the illusion so that the viewer
feels immersed in the scene, as if he was there himself! |
The wide angle lenses can give very dramatic and
exciting results if used properly. Unfortunately many photographers fail
to learn the techniques for utilizing the wide-angle lenses to their fullest.
The next time you hit the streets with your wide-angle lenses, take notes
of the above tips, and I promise you that your images will improve instantly!
All text and photos
by Nelson Tan
Copyright (C) 2002
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