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Sigma AF 105mm f/2.8 EX DG macro - 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 November 2005
Special thanks to Sander Vermeulen for providing this lens!
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. As such it is still 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
APS-C DSLRs the field-of-view of the
lens is equivalent to 168mm 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 optical construction is made of 11 elements in 10 groups without any special elements.
The lens features 8 aperture blades. Typical for most macro lenses the lens provides a
max. magnification of 1:1 at a min. focus distance of 0.313m. The filter size is 58mm.
With a weight of 460g and a size of 74x97mm it is pretty compact - at least a infinity focus.
The length of the lens grows substantially when focusing towards closer distances as
you may notice in the product image above.
The construction feels very solid with the typical EX ("Excellence") finish
(crinkle style). The very broad, rubberized focus ring operates very smooth and is well
damped. 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. The idea behind this remains somewhat mysterious because you
still have to switch the lens from AF to manual focusing - independent from the
dual-focus mechanism that is.
The AF speed is quite decent though not remotely in the same league like its Canon counterpart.
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