Pentax SMC DA* 55mm f/1.4 SDM - Review / Test Report
Lens Reviews - Pentax

Review by Klaus Schroiff, published November 2009

Special thanks to Claus Durst for providing this lens for testing purposes!


The Pentax SMC-DA* 55mm f/1.4 SDM represents one of the rather seldom updates that we're seeing in this lens class. Usually standard lens designs are kept for decades - some current original lens designs date back to the 70s(!) like e.g. the Canon EF 50mm f/1.8. However, perhaps even more surprising is the designation of the Pentax lens. It is a DA* which identifies members of the professional grade segment in the Pentax lineup. While this is certainly promising it has also an immediate drawback - the DA* 55mm f/1.4 SDM is far, far ... did I mention "far" ? ... more expensive than conventional AF standard lenses. In fact the price has more than doubled to around 650EUR/US$ compared to the old FA 50mm f/1.4 and this did naturally cause some headaches in the community whether this is actually justified. We'll see. The DA* 55mm f/1.4 SDM is the first Pentax lens to feature the new "Aero Bright Coating" which is supposed to deliver superior flare suppression. We've seen similar announcements from Nikon (N-coating) and Canon (Sub Wavelength Coating) so this follows a trend although the effect on the final image quality wasn't overly significant as far as we could tell (across all these brands).

Pentax DSLRs rely on APS-C image sensors so in full format terms the field-of-view is equivalent to about 85mm whereas the depth-of-field capability resembles a f/2 lens. The light gathering characteristic remains coupled to the original (max) f/1.4 of course. A "85mm f/2" is in the sweet spot of portrait photography for instance so it is actually quite smart to provide a new option here especially because full format DSLRs are out-of-scope in Pentax land.

The build quality of the Pentax lens is up to professional standards including a sealing against dust and humidity. The quality of the used materials is excellent and the focus ring operates very smooth. The lens is comparatively large and heavy both compared to the competition as well as to the native Pentax Ltd lenses (although there's no directly competing lens here). The physical size of the lens does not change although the inner lens tube moves during focusing. The front element does not rotate. The Pentax Super Protect (SP) coating on the front element has been optimized to repel dust, water and grease.

The AF relies on Pentax' ultrasonic motor (SDM = "supersonic drive motor"). The lens focuses fairly fast but don't expect it to be a speed daemon. The noise level is quite low although you may notice some high frequency sound during AF operations (in our sample at least). Full-time manual focusing, Pentax calls it "Quick-Shift", is possible in single shot AF mode.

Equiv. focal length82.5 mm (full format equivalent)
Equiv. aperturef/2.1 (full format equivalent, in terms of depth-of-field)
Optical construction9 elements in 8 groups
Number of aperture blades9 (circular)
min. focus distance0.45 m (max. magnification ratio 1:5.9)
Dimensions66 x 71 mm
Weight375 g
Filter size58 mm (non-rotating)
Hoodbarrel-shaped, supplied, bayonet mount
Other featuresAero Bright Coating, SP coating, Quick-Shift AF, SDM