130
Exploring Photography
Bellows
A bellows is not a variation of an exten-
sion tube. A bellows is a folding cloth sleeve
device that provides a lighttight adjust-
able tube between the lens and camera. See
Figure 7-13. A bellows has a different range of
magnifi cation. A bellows is best used when the
subject is smaller than 1″. They are rather bulky
for portable operations and are expensive.
Usually, bellows have a scale showing the
magnifi cation ratio. As with extension tubes,
additional exposure time is required with
bellows.
Macro and Close-Focus Lenses
Macro lenses will focus much closer than
regular lenses. In a true sense, a macro lens
is capable of providing a 1:1 magnifi cation
ratio (life-size image). The term is sometimes
incorrectly used to describe a close focus lens.
Magnifi cation ratios are usually engraved on
the macro lens barrel. See Figure 7-14. Many
will focus to 1/2X or a 1:2 ratio, but may be
fi tted with an extension ring to allow focus-
ing down to life-size. Still, others will focus to
a 1:1 ratio or life-size without any additional
accessories. Macro lenses can also be used at
normal subject distances.
There are some things to remember when
using extension tubes:
• Longer focal length lenses will give a
greater working distance.
• Wide-angle lenses do not give a greater
depth of fi eld than normal lenses when
used with extension tubes. A wide angle
lens with extension tubes will give a
greater magnifi cation of the subject at the
cost of more distortion.
• Magnifi cation ratios must be determined
from data charts furnished with the
extension tubes.
• If your camera does not have through-the-
lens metering, exposure compensation
must be calculated. Again, refer to the data
charts furnished with the extension tubes.
In general, as the lens is moved farther
from the fi lm, more light is needed to
make the exposure. This requires a larger
lens opening or slower shutter speed.
Bracketing shots is recommended.
• Extension tubes give best results when the
subject is larger than 1″.
Figure 7-12. Extension tubes are fi tted between the
lens and camera body. These tubes can be used
individually or in combination. The longer the tube,
the closer the lens can be focused on the subject.
Figure 7-13. Although more costly and cumbersome,
a bellows is more fl exible to use than a close-up lens
or an extension tube. (Pentax Corp.)