Understand the Lingo
of Macro Lenses
With rare exception, close-up lenses are not described in terms of focal length, as are other
lenses. That??™s because they??™re essentially just magnifying glasses that go in front of the
camera??™s normal lens. Instead, close-focus lenses are described using the term diopter.
A diopter is an indirect measure of focal length. It tells you both how close you can get
to the subject and what relative magnification the lens provides. Specifically, the diopter
number indicates how close your camera lens can focus with the lens set to infinity and the
close-up lens attached, in fractions of a meter. A +2 rating will let your camera focus 1/2
meter away, while a +3 rating focuses at 1/3 meter away, and so on. Believe it or not, these
diopter numbers hold true no matter what the focal length of your camera lens. Close-up
lenses typically come in a variety of strengths, from +1 to +10.
128 How to Do Everything: Digital Camera
In fact, lots of subjects look radically different at close range and magnified than they appear
from a human perspective. Some subjects can even take on an almost fractal appearance??”that
is, their underlying structure can seem to have a nearly infinite amount of complexity, as you can
see from these ice crystals on a tree branch, captured on a chilly April morning:
That??™s why I think macro photos make for some very exciting images.
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