76 Working with Aperture
Macro Photography and Aperture
Macro Photography and Aperture
Some people use the phrase macro photography to ap-
ply to any close-up work. A more stringent definition
is that macro photography is the creation of close im-
ges in which the physical size of the capture is greater
than the size of the object being photographed. For ex-
mple, if a coin with a one-inch diameter is captured
by your sensor so that the pixels making up the coin
measure an inch in diameter, that is called a 1:1 cap
ure. If the pixels on the sensor made up a ratio of 1.5:1
compared to the subject, then the size of the capture is
said to be greater than life.
How Do Extension Devices Work?
The best macro gear for dSLRs works by adding space between
the lens and the camera. This is how extension tubes, bellows,
and (in combination with special optics) macro lenses work.
The added space increases the focal length of the lens
combined with the extension device. (See “Understanding
f-Numbers and f-Stops” on page 52 for a dention of focal
Since f-numbers are dened in terms of the ratio of eective
focal length to the diameter of the aperture, in some cases very
small f-stops result, like f/36, f/40, or even f/64, which may be
smaller than the hardware rating for minimum f-stop of the
lens without the extension device.

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