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Pentax SMC-FA 20mm f/2.8 - Review / Test Report |
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Lens Reviews -
Pentax
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Page 1 of 3
Review by Klaus Schroiff, published May 2007
Special thanks to Knut Kampe for providing this lens!
Introduction
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.
| Specifications |
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| Equiv. focal length | 30 mm (full format equivalent) |
| Equiv. aperture | f/4.2 (full format equivalent, in terms of depth-of-field) |
| Optical construction | 10 elements in 9 groups |
| Number of aperture blades | 6 |
| min. focus distance | 0.25m (max. magnification ratio 1:8.3) |
| Dimensions | 70x44mm |
| Weight | 255g |
| Filter size | 67mm (non-rotating) |
| Hood | optional |
| Other features | - |
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