Pentax SMC-FA 20mm f/2.8 - Review / Test Report
Lens Reviews - Pentax

Review by Klaus Schroiff, published May 2007

Special thanks to Knut Kampe for providing this lens!


The Pentax SMC-FA 20mm f/2.8, a full format lens, is discontinued by now but it may be interesting to have a look how it compared to the current SMC-DA 21mm f/3.2 Limited. When used on APS-C DSLR the FA 20mm f/2.8 has a field-of-view equivalent to 30mm so it leaves its original ultra-wide scope towards a mainstream wide-angle.

The build quality of the lens is fine but nothing to rave about either. Subjectively the plastic quality could be a little better. The small rubberized focus ring operates very smooth. The lens extends a tiny bit when focusing towards closer focus distances. The front element does not rotate so using a polarizer is not a problem.

The lens has no internal AF motor and relies on a slotted drive screw operated by the camera. As a result AF operation will generate a moderate degree of noise. The AF speed is very fast on the K10D.

Equiv. focal length30 mm (full format equivalent)
Equiv. aperturef/4.2 (full format equivalent, in terms of depth-of-field)
Optical construction10 elements in 9 groups
Number of aperture blades6
min. focus distance0.25m (max. magnification ratio 1:8.3)
Filter size67mm (non-rotating)
Other features-

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