Pentax SMC-FA 20-35mm f/4 AL - Review / Lab Test
Lens Reviews - Pentax
Article Index

Review by Klaus Schroiff, published May 2007

Special thanks to Rüdiger Neumann for providing this lens!


The Pentax SMC FA 20-35mm f/4 AL is one of the FA series lenses that has been discontinued just recently (in most markets at least). The current Pentax SMC DA 16-45mm f/4 ED AL is the obvious replacement for this old fellow. The FA 20-35mm f/4 AL is a full format lens with a field-of-view equivalent to 30-53mm when used on an APS-C DSLR. This range is still fairly useful within this scope but a 1.75x zoom ratio isn't really attractive anymore.

The build quality of the lens is Ok although nothing to rave about. The outer body is made of fairly average quality plastics and the control rings don't feel overly tight (on this used sample). The inner lens tube moves when zooming or focusing and it reaches its longest extension (about 2cm) at 20mm and minimum focus. The front element does not rotate so using a polarizer is no 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 length30-52.5 mm (full format equivalent)
Equiv. aperturef/6 (full format equivalent, in terms of depth-of-field)
Optical construction10 elements in 8 groups inc. 2 aspherical elements
Number of aperture blades8
min. focus distance0.3 m (max. magnification ratio 1:6.3)
Dimensions70 x 68 mm
Weight245 g
Filter size58 mm (non-rotating)
Hoodpetal-shaped, snap-on type (supplied)
Other features-