Pentax SMC-DA 18-135mm f/3.5-5.6 ED AL [IF] WR - Review / Lens Test
Lens Reviews -
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Review by Klaus Schroiff, published April 2011
The Pentax SMC-DA 18-135mm f/3.5-5.6 ED AL [IF] WR is one of the kit lens options sold with the Pentax K-5 but it's now also available as a separate option. By today's standards its 7.5x zoom ratio is no longer extreme - the Tamron 18-270mm VC PZD has a whopping 15x factor for instance - but it certainly follows a "one-size-fits-all" approach. In full format terms its field-of-view is equivalent to "28-200mm" so it covers everything from moderate moderate wide-angles to fairly long tele settings - combined with a moderate max. aperture. In Europe it sells for just around 600EUR whereas you can pick it up for less than 500US$ in the US ... which makes you wonder about the global pricing policy somehow. In any case it's a comparatively expensive offer - even the now discontinued Pentax SMC-DA 18-250mm f/3.5-6.3 was quite a bit cheaper. Consequently our expectation were quite high prior of this test.
Upon first contact we were positively surprised by the very high build quality of the lens. The lens body is made of a tightly assembled combination of (mostly) metal and plastic parts. The lens uses a duo-cam zooming mechanism which extends towards the long end of the focal length range. However, the inner lens tubes have only very marginal play and our sample did not show any zoom creeping. The Pentax lens is "WR" (=weather resistent) which is a very unusual feature in this lens class. According to Pentax it's a simplified version with 6 seals. Additionally Pentax applied a water- & dust-repellent coating to the front element (SP coating). The very broad rubberized zoom ring operates smoothly. The focus ring is comparatively tiny but accurate manual focusing is possible. The lens features an IF (internal focusing) so the front element does not rotate during focus operations. A petal-shaped lens hood (with filter window) is part of the package.
The Pentax lens features an internal "direct current" (DC) motor for focusing which is reasonably fast combined with low noise emissions. The focus accuracy of our test sample was very good. "Quick Shift" - manual focusing in single-shot AF - is supported.
|Equiv. focal length||27-202.5 mm (full format equivalent)|
|Equiv. aperture||f/5.3-f/8.4 (full format equivalent, in terms of depth-of-field)|
|Optical construction||13 elements in 11 groups inc. 2x aspherical (glass molded & hybrid) + 1x ED elements|
|Number of aperture blades||7 (circular)|
|min. focus distance||0.4 m (max. magnification ratio 1:4)|
|Dimensions||73 x 76 mm|
|Filter size||62 mm (non-rotating)|
|Hood||petal-shaped, plastic, bayonet mount (supplied), filter window|
|Other features||weather sealing, SP-coating, supports Quick Shift Focus System|