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Deeper zone of focus is usually
associated with smaller apertures and shorter focal length lenses such as super wide-angles,
wide-angles and to some extent, standard 50mm lens. However, longer telephoto lenses
can also be used for a greater zone of sharpness. This can be done in two ways -
the first is of course, via the use of smaller apertures to maximize depth-of-field,
and the second is by focusing the lens at infinity. At infinity, the depth-of-field
is absolutely indefinite for any focal length, meaning it is virtually impossible
to achieve a shallow zone of focus whenever a lens has been focused at its infinity
distance.
The photo (below, left) of the huge crowd was shot at the telephoto end of the EF
55-200mm f/4.5-5.6 USM zoom lens and focused at infinity. While most of the press
and sports photographers present were keen to shoot the crowd at a close distance
with wide-angle lenses, I saw a better angle from the window of the first floor paddock
I was in, located quite a distance from where the crowd was. The selected aperture
of f/8.0 did little in extending the zone of sharpness for this photo.
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Shot at infinity focus (200mm) |
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A small aperture was selected for
this shot (f/8.0) |
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Close-up of loose thread (EF 100mm
Macro) |
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Bamboo baskets (at f/4, 200mm) |
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For the photo of the marigolds,
a smaller aperture - needless to say - was selected with the EOS-3 to ensure adequate
depth-of-field across the whole frame. The close-up photo of the loose thread was
shot at f/2.8 to ensure a handhold-able shutter speed and a blurred background. For
the bamboo baskets, they were among those that caught my attention as I was going
around looking for subject matters to be photographed with the EOS-3 in its Av mode.
Using the Av mode can be fun, especially when you prefer to have some control over
the depth-of-field in your photos although nothing beats using the Intelligent Program
AE mode in terms of ease-of-usage. However, while the Program AE mode allows you
to alter the camera's suggested setting by turning the EOS-3's Main Dial left or
right but sometimes, the altered setting may not give you the f-stop you want. For
example, if you prefer f/8.0, the altered values will instead be f/7.1 or f/9.0.
Thus, the Av mode allows you the freedom to choose the f-stop you want and let the
camera decide the appropriate shutter speeds.
Below are four other examples of how the Av mode was used to create the effects shown.
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