Sigma AF 105mm f/2.8 EX DG macro (Nikon mount) - Review / Lab Test Report
Lens Reviews - Nikon / Nikkor (APS-C)
Article Index
Introduction
Analysis

Lens kindly provided for testing purposes by Julio M. Alperi Gonzalez!

Introduction

The Sigma AF 105mm f/2.8 EX DG macro is a recent update to the well-known Sigma AF 105mm f/2.8 EX macro. However, it is not a totally new lens - the new DG (Digital) designation refers to an improved coating optimized for digital sensors but other than that the design doesn't seem to have changed. This is actually not a bad sign because its predecessor had a pretty good reputation. It's a full format lens so naturally the lens remains also usable on film SLRs as well. On the Nikon D200 (APS-C DSLR) the field-of-view of the lens is equivalent to about 159mm on full frame cameras. The primary application of the lens is, obviously, macro photography but it's not limited to that - infinity focus is possible.


The construction feels very solid with the typical Sigma EX ("Excellence") finish (crinkle style). The very broad, rubberized focus ring operates very smooth and is well damped. Typical for most macro lenses the length of the lens grows substantially when focusing towards closer distances. Besides the lens and a dedicated bag the package also includes a screw-in, barrel-type lens hood but this is really a strictly optional accessory item because the front element resides deep within the lens (about 2cm below the front - see below).

Thanks to the screw-in approach there're advantages with polarizers which can still be used with a mounted hood. The front element of the lens does not rotate. 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. In "manual focus" mode the camera's AF screw drive remains coupled so unless you disable AF on the camera you will end with a rotating focus ring. On the D200 the AF speed is fine for a macro lens but you should take advantage of the focus limiter when using the lens for non-macro applications in order to avoid focus hunting throughout the focus range.

Specifications
Equiv. focal length157.5 mm (full format equivalent)
Equiv. aperturef/4.2 (full format equivalent, in terms of depth-of-field)
Optical construction11 elements in 10 groups
Number of aperture blades8
min. focus distance0.313 m (max. magnification ratio 1:1)
Dimensions74 x 97 mm
Weight460 g
Filter size58 mm (non-rotating)
HoodBarrel shaped (supplied)
Other featuresOne-touch focus clutch. Focus limiter.




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