Canon EF 180mm f3.5L Macro USM - Manual (Page 9)

ENG-8
8. About Exposure
• The correct exposure for a close-up shot largely
depends on the subject. Therefore, it is
recommended to take several shots of the same
subject at different exposures.
• When taking close-up shots, it is recommended
to use aperture-priority AE (Av) or Manual (M)
picture-taking modes, because depth of field
and exposure are easy to adjust in those
modes.
Setting the Exposure
When taking photographs using TTL
metering, no exposure compensation is
necessary to meter the light coming through
the lens.
With TTL metering, AE (autoexposure) is
possible at all focusing distances. Just set the
desired picture-taking mode, then check the
shutter speed and aperture before taking the
picture.
Magnification and Effective f-number
The aperture displayed by the camera assumes
that the focus is set to infinity. The actual
aperture (effective f-number) becomes darker
(effective f-number increases) at closer focusing
distances (magnification increases). This does
not cause exposure problems for normal picture-
taking. However, for closeup photography, you
cannot ignore the change in the effective f-
number.
When you use a handheld exposure meter to
set the exposure, you must take into account
the exposure factor shown in the following
table.
Magnification 1:10 1:5 1:3 1:2 1:1.5 1:1.2 1:1
Effective f/No. 3.8 4 4.3 4.7 5 5.4 5.8
Exposure in stops – – + + +1 +1 +1
Factor (stops) in stops – – + + +1 +1 +1
1
2 1
2 1
2 1
2
1
3 1
3 2
3 2
3 1
3
COP
Y