Sigma AF 24-70mm f/2.8 EX DG macro (Canon) - Review / Lab Test Report
Lens Reviews - Canon EOS (APS-C)
Article Index
Introduction
Analysis

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
Equiv. focal length38-112 mm (full format equivalent)
Equiv. aperturef/4.5 (full format equivalent, in terms of depth-of-field)
Optical construction14 elements in 12 groups inc. 2x SLD and 3x aspherical elements
Number of aperture blades9
min. focus distance0.40 m (max. magnification ratio ~1:3.8)
Dimensions89 x 116 mm
Weight715 g
Filter size82 mm (non-rotating)
Hoodsupplied, petal-shaped
Other featuresDual Focus (DF) system




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