|
Sigma AF 105mm f/2.8 EX DG macro (Nikon mount) - Review / Lab Test Report |
|
Lens Reviews -
Nikon / Nikkor (APS-C)
|
|
Page 1 of 2
Review by Klaus Schroiff, published July 2006
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 length | 157.5 mm (full format equivalent) |
| Equiv. aperture | f/4.2 (full format equivalent, in terms of depth-of-field) |
| Optical construction | 11 elements in 10 groups |
| Number of aperture blades | 8 |
| min. focus distance | 0.313 m (max. magnification ratio 1:1) |
| Dimensions | 74 x 97 mm |
| Weight | 460 g |
| Filter size | 58 mm (non-rotating) |
| Hood | Barrel shaped (supplied) |
| Other features | One-touch focus clutch. Focus limiter. |
|
