Sigma AF 24mm f/2.8 macro (Pentax K) - Review / Lab Test Report
Lens Reviews - Pentax
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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 than usual.

Equiv. focal length36 mm (full format equivalent)
Equiv. aperturef/4.2 (full format equivalent, in terms of depth-of-field)
Optical construction8 elements in 7 groups
Number of aperture blades6
min. focus distance0.18 m (max. magnification ratio 1:4)
Dimensions64 x 43 mm
Weight250 g
Filter size52 mm (non-rotating)
Hoodflower-shaped, snap-on type
Other features-

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