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Sigma AF 24mm f/2.8 macro (Pentax K) - Review / Lab Test Report |
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Lens Reviews -
Pentax
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Page 1 of 2
Review by Klaus Schroiff, published December 2007
Special thanks to Knut Kampe for providing this lens!
Introduction
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
than usual.
| Specifications |
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| 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 |
| Weight | 250 g |
| Filter size | 52 mm (non-rotating) |
| Hood | flower-shaped, snap-on type |
| Other features | - |
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