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Sigma AF 24-70mm f/2.8 EX DG macro (Canon) - Review / Lab Test Report |
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Lens Reviews -
Canon EOS (APS-C)
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Page 1 of 2
Review by Klaus Schroiff, published September 2007
Special thanks to Lincoln Westfall for providing this lens!
Introduction
The AF 24-70mm f/2.8 EX DG macro is one of the full format standard zooms made by
Sigma. Sigma produces a couple of lenses in this specific segment but this is their high end model.
Fortunately a Sigma EX lens doesn't necessarily come at a high-end price - in fact
at around 400US$/€ it is a pretty affordable lens. The Sigma is available in most major
mounts (except for 4/3 where it wouldn't make much sense anyway).
On APS-C DSLRs its field-of-view is equivalent to a ~38-112mm which is
surely attractive regarding the "long" end of the zoom range but the 38mm setting doesn't really
qualify it as a standard zoom within this scope anymore - naturally this is a fate it shares with
all full format standard zooms when used on APS-C DSLRs.
The Sigma is a rather massive standard zoom lens. It requires 82mm filters so be suffer
when investing into a polarizer (although you may consider a step-down ring when
using the lens on an APS-C DSLR). Interestingly its principal design is fairly similar
to the Canon EF 24-70mm f/2.8 USM L - reads: it extends when zooming towards the WIDE-end
of the zoom range which is relatively unusual. The product image below may suggest something
else but the lens has only a single inner lens tube. The build quality of the lens is very
fine thanks to high quality materials and smooth control rings (the rubber of the zoom ring
of the tested (used) sample collected some dust over time). The lens
suffers a bit of zoom creeping though.
The AF 24-70mm f/2.8 features a conventional micro motor. However, the AF is pretty
snappy and the generated noise level during operations is fairly low. The lens incorporates
a Dual-Focus (DF) mechanism which allows to decouple the focus ring from the focusing gear
by pulling/pushing it back and forth (a little stiff). The idea is good although the
implementation leaves a bit to be desired because there's still a "normal" AF/MF switch.
| Specifications |
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| Equiv. focal length | 38-112 mm (full format equivalent) |
| Equiv. aperture | f/4.5 (full format equivalent, in terms of depth-of-field) |
| Optical construction | 14 elements in 12 groups inc. 2x SLD and 3x aspherical elements |
| Number of aperture blades | 9 |
| min. focus distance | 0.40 m (max. magnification ratio ~1:3.8) |
| Dimensions | 89 x 116 mm |
| Weight | 715 g |
| Filter size | 82 mm (non-rotating) |
| Hood | supplied, petal-shaped |
| Other features | Dual Focus (DF) system |
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