Sigma AF 30mm f/1.4 EX DC (Pentax K) Review / Test Report
Lens Reviews - Pentax

Review by Klaus Schroiff, published May 2007

Special thanks to Jonas B. for providing this lens!


The AF 30mm f/1.4 EX DC is one of Sigma's Digital Camera lenses designed specifically for APS-C DSLRs. Its field-of-view as well as the high speed resembles classic standard lenses (50mm) on full-frame camera. In Pentax land it competes against the Pentax SMC FA 31mm f/1.8 Limited - a full format lens with a 2.5x higher price tag despite being somewhat slower regarding its max. aperture. So the Sigma is obviously an attractive alternative at least on paper so let's see whether it can match or beat the real thing ...

The construction feels very solid with the typical Sigma EX ("Excellence") finish (crinkle style). The very broad, rubberized focus ring has a smooth action. The front element does not rotate so using a polarizer is no problem.

The image above shows the Canon variant of the lens

The Sigma has no internal AF motor and relies on a slotted drive screw operated by the camera. Consequently AF operations generate a moderate degree of noise. The AF speed is very fast on the K10D.

Equiv. focal length45 mm (full format equivalent)
Equiv. aperturef/2.1 (full format equivalent, in terms of depth-of-field)
Optical construction7 elements in 7 groups inc. 1 SLD (Special Low Dispersion), 1 ELD (Extraordinary Low Dispersion) and 1 aspherical element
Number of aperture blades8
min. focus distance0.4 m (max. magnification ratio 1:10.4)
Dimensions77x59 mm
Weight430 g
Filter size62 mm (non-rotating)
Hoodpetal-shaped, snap-on type (supplied)
Other features-

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