Sigma AF 24mm f/2.8 macro (Pentax K) - Review / Lab Test Report
Lens Reviews -
Tuesday, 25 December 2007 20:35
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Special thanks to Knut Kampe for providing this lens!
The Sigma AF 24mm f/2.8 macro is another "legacy" lens from the late 80s to
early 90s. It has been discontinued in the meanwhile and Sigma replaced it with the
current AF 24mm f/1.8 EX. It is obviously a full format lens and when used
on the Pentax K10D its field-of-view is equivalent to about 36mm so it is a moderate
wide angle in this scope.
The build quality of the lens is very decent. The outer shell is a combination
of plastic and metal parts assembled with tight tolerances. The small
focus ring operates fairly smooth but sounds a little "scratchy". As you can
see below the lens extends a little bit towards closer focus distances.
The Sigma can focus down to just 18cm (1:4 magnification) which is quite
unusual for a lens in this class. The front element does not rotate so using
a polarizer is no problem.
Typical for most AF lenses in Pentax mount the Sigma has no internal AF motor
and relies on a slotted drive screw operated by the camera.
The AF speed is very fast on the K10D but the noise level is a little higher
|Equiv. focal length||36 mm (full format equivalent)|
|Equiv. aperture||f/4.2 (full format equivalent, in terms of depth-of-field)|
|Optical construction||8 elements in 7 groups|
|Number of aperture blades||6|
|min. focus distance||0.18 m (max. magnification ratio 1:4)|
|Dimensions||64 x 43 mm|
|Filter size||52 mm (non-rotating)|
|Hood||flower-shaped, snap-on type|