Sigma APO 100-300/4 EX IF HSM 用户手册 (en)

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Lens Review...
Sigma APO 100-300/4 EX IF HSM
Text and Photography Copyright Jim Erhardt
All rights reserved.
The decision of what lens to buy for wildlife photography always seems mired in
compromise. Along with the budget limitations most of us face in buying equipment, the
debate over prime lenses versus zooms, and "original equipment manufacturer" versus
"third party manufacturer" cloud the decision making process as well.
While just about every manufacturer offers at least one model in the 75mm (or 100mm) to
300mm range, just about all of these lenses are variable aperture lenses, typically f/4.5 to
f/5.6. Along with the slower shutter speeds associated with the use of these models, the
addition of a teleconverter will usually result in the loss of autofocus operation and
substantial degradation of optical performance. However, for the nature photographer
there's no denying the utility of a telephoto lens in this zoom range.
viable alternative for the serious nature photographer looking for a telephoto lens in this
range of focal lengths. Along with the handy range of focal lengths, it provides a constant f/4
maximum aperture, internal HSM focusing and internal zooming. In other words, regardless
of zoom or focus setting, the lens does not change in physical length and the maximum
aperture of f/4 is available at all focal lengths. Additionally, the lens can be used with
Sigma's EX series of teleconverters. I recently had the opportunity to spend some time with
this lens (and Sigma's matching 1.4X teleconverter) in a Canon mount.
Like Sigma's other EX super-telephoto lenses, the lens is far more solidly built than the
typical "consumer" version of the 100-300 zoom. It features a wide, very smooth turning
focus ring and a separate zoom ring, which is large and smooth in operation as well. The
Sigma, Canon and Nikon mount versions of this lens include Sigma's HyperSonic Motor
(HSM) focusing motor, which also allows for full-time manual focus override. The lens also
includes a removable tripod mount collar, a very handy feature for the nature photographer.
The lens features Sigma's attractive black-speckled EX finish and is supplied with a large
matching lens hood. Overall, the build quality of this lens is very impressive.
Other 
16 elements in 14
groups optical
construction, including
two Special Low
Dispersion (SLD)
elements
●   
9-blade aperture (f/32
minimum aperture)
●   
180cm/70.9 inches
minimum focusing
distance (1:5
magnification ratio)
●   
92.4mm (3.6 inches)
maximum width by
224mm (8.8 inches) in
length
●   
1480 grams (52.2
ounces) in weight
●