The Pentax DA* 200mm SMC f/2.8 ED (IF) SDM is a high-end prime lens with an impressive specification
On the outside, the lens is fully sealed against dust, dirt and splashes and also benefits from Pentax’s SP (Super Protection) coating on the front element to resist contamination by both oily and water-based substances. Inside, it makes use of ED glass to reduce chromatic aberration and is fitted with an SDM (Super-sonic Direct-drive Motor) inner-focussing AF system that promises quick and quiet operation.
Being a prime lens there is but a single collar on the barrel, generously sized and ideally located just forward of the middle of the lens. To the rear of the manual-focussing collar are a focussed-distance window (with depth-of-field markings for f/22) and an AF/MF selector.
Manual adjustments can be applied at any time in AF mode but the resistance offered by the collar is perhaps just a shade too much for comfort.
A generous lens hood is supplied but it is easily dislodged from its storage position, making it a potential liability when handling the lens. More positively, the hood has a trap door that can be removed to allow polarising filters to be rotated in situ.
The barrel itself has a powder-coated texture that makes the lens easy to grip. The flange at the front adds to a feeling of security when picking-up the lens and also blends into the hip on the back of the lens hood.
The only obvious omission from this lens is the provision of image stabilisation technology‚ but that would add to both its bulk and its cost.
Technical testing revealed minor signs of chromatic aberration but a very strong set of MTF results: it is a shame there is a slight drop at f/2.8 but peak performance, between f/5.6 and f/8, approaches an exceptionally impressive 0.4 cycles-per-pixel. Pentax has sensibly limited the minimum aperture to f/22, at which setting the MTF curve only just falls below the critical 0.25 cycles-per-pixel threshold.
Field testing confirmed the speed and quietness of the AF system and the ease-of-use of the lens in general. Sadly, it was possible to observe colour fringes towards the edges of the frame in some real-world images.