Pentax SMC-K 135mm f/2.5 - Review / Lab Test Report
Lens Reviews -
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Special thanks to Ruediger Neumann for providing this lens!
Ruediger has supplied lots of new Pentax lenses for testing and
he also sneaked a specialty into the last package - an old Pentax SMC-K 135mm f/2.5.
The lens is about as old as time itself ... well, make it the late 70s/early 80s - the
pre-AF era. In fact the K 135mm f/2.5 doesn't even offer aperture priority on the K10D
(due to the crippled KFA2 mount here) and you have to use stop-down metering
using the camera's green button. The selected aperture is not visible in
the viewfinder. So you may ask why bother anyway ? Well, SMC-K/M/A lenses are usually
dirt cheap on the used market and some may come in handy regarding the current deep dark
gaps in the Pentax lens lineup. Besides it is surely interesting to have a look how a
(sort of) stone-age lens behaves on a current APS-C DSLR. In this scope the field-of-view
of the K 135mm f/2.5 is equivalent to about ~205mm on classic full format cameras.
In terms of build quality the SMC-K 135mm f/2.5 feels like a rock. Even after
30 years it makes many current AF lenses look like cheap toys. The broad, rubberized
focus ring operates exceptionally smooth and very well damped. The lens extends
a bit when focusing towards close distances.
|Equiv. focal length||202.5 mm (full format equivalent)|
|Equiv. aperture||f/3.8 (full format equivalent, in terms of depth-of-field)|
|Optical construction||6 elements in 6 groups|
|Number of aperture blades||8|
|min. focus distance||1.5 m (max. magnification ratio ?)|
|Dimensions||68 x 86 mm|
|Filter size||58 mm (non-rotating)|
|Hood||barrel shaped, snap-on type (optional)|