Pentax D-FA 100mm F/2.8 Macro WR
Compared with the older Pentax 100mm macro lens, this redesigned WR (Weather Resistant) version features weather seals that make it more rugged for outdoor photography. Cosmetic differences include a focus distance scale that is no longer behind glass (or plastic) and you get a big depth of field indicator, even though this is a bit superfluous because, at close focusing distances for macro work, you hardly get any depth of field anyway.
Build quality feels robust, and the lens itself is remarkably compact for a 100mm full-frame macro lens. Plus it has a weight that is less than half that of the competing Nikon lens, making it a good balance on Pentax’s typically compact SLR bodies, such as the K-x and K-7.
The autofocus mechanism is a little noisy, but nowhere near as shrill as in the previous Pentax 100mm macro we reviewed. Of far greater concern is that, mounted on a K-7 body during our tests, the autofocus would frequently lurch between a variety of focus settings and then come to an abrupt stop in completely the wrong place, or worse still, hunt backwards and forwards through the entire focus range without managing to lock onto the target. Plus, since there is no focus limit switch, erratic autofocus becomes an even more irritating and time-consuming problem.
The outright sharpness of the Pentax proved particularly good at its maximum f/2.0 aperture, but in the more useful f/8 to f/16 aperture range, it was only mediocre.
Sony 100mm F/2.8 D Macro
The price of Sony’s 100mm Macro is edging up towards the Canon and Nikon big boys, but unlike those lenses, there is no advanced, whisper-quiet autofocus or optical stabilisation. And even though current Sony DSLR bodies tend to feature sensor-shift stabilisation as a substitute, you have to wonder where the extra cost is going. Autofocus is certainly fairly slow and noisy, and there are no fancy frills such as full-time manual focus override or even a quick-action, push-pull AF/MF focus action like on the Sigma, Tamron and Tokina lenses.
On the plus side, you do get a focus limit switch that operates either side of 0.6m, and there is also a focus hold button, which locks the focus setting regardless of subsequent presses of the shutter release button. This could be quite useful for portraiture, but we cannot really fathom any practical value for macro work. Build quality feels pretty reasonable, although the focus ring is quite stiff and jerky.
The Sony’s biggest surprise came in terms of image quality. Mounted on an Alpha 450 body, there was something of a reversal in fortunes compared with another review sample that we tested about 18 months ago. The previous sample proved particularly sharp right into the corners of the frame, but had noticeable red/cyan color fringing. This time around, sharpness was quite disappointing, but there was practically no sign of any chromatic aberrations. In both cases though, macro test shots were a little lacking in contrast.