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Pentax SMC-FA 20-35mm f/4 AL - Review / Lab Test |
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Lens Reviews -
Pentax
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Review by Klaus Schroiff, published May 2007
Special thanks to Rüdiger Neumann for providing this lens!
Introduction
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.
| Specifications |
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| Equiv. focal length | 30-52.5 mm (full format equivalent) |
| Equiv. aperture | f/6 (full format equivalent, in terms of depth-of-field) |
| Optical construction | 10 elements in 8 groups inc. 2 aspherical elements |
| Number of aperture blades | 8 |
| min. focus distance | 0.3 m (max. magnification ratio 1:6.3) |
| Dimensions | 70 x 68 mm |
| Weight | 245 g |
| Filter size | 58 mm (non-rotating) |
| Hood | petal-shaped, snap-on type (supplied) |
| Other features | - |
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