14 September 2010

Cafe Colbar Walkabout with the DA 17-70mm f/4 SDM

For a time I have been using the Sigma 17-70mm f/2.8-4.5 zoom as a walkabout lens for traveling. This lens has served me well as a replacement to the trusty DA 16-45mm f/4 that I had owned quite awhile back. The DA 16-45mm offers an affordable ultrawide capability with even sharpness and a good step up from the DA 18-55mm kit lens. The constant f/4 maximum aperture and the extra wide angle coverage is nice, but there were some reasons which made me decide to replace it with the Sigma.

For one, I had serious doubts on the long term durability principally because the build quality feels cheap. The zoom and focus rings are overly light and the lens design has the quirky feature of having the lens barrel extend at the widest 16mm setting, creating hopelessly obvious vignetting if one needed to use the built-in pop-up camera flash. My copy exhibited an obvious tendency towards underexposure too. But perhaps the biggest issue of the DA 16-45mm as a walkabout lens is the limited zoom range at the long end. In this regard, the 17-70mm focal range does offer somewhat better versatility, which was why I opted for the Sigma.

The Sigma is a fine lens with good center sharpness, compact size and a good close focus ability. About the only thing I didn't like about it was the rather obvious barrel distortion at the the wide end, the variable aperture when zooming and subjectively speaking the slight difference in color rendering. I'd consider these minor issues and would still recommend it. I got mine cheap and it gave me good service, being the main lens used at a recent holiday.

I like the 17-70mm zoom range and I like the color rendition of Pentax lenses. So when the opportunity arose for a trade with my DA 70mm Limited, I decided it was time to try out the DA 17-70mm f/4 SDM. It may not be a DA* lens but the obvious build quality is noticeable, certainly quite a bit better than the now discontinued DA 16-45mm. The best feature has to be the silent focusing of the SDM motor and matched with the extremely quiet shutter of the K-7, there's plenty of opportunities to shoot discreetly. Image quality is on par with other consumer zooms and it delivers colors that are punchy and contrasty. Light falloff at the corners isn't so obvious, even wide open.

The lens already focuses pretty quick due to the short focus throw from infinity to 0.28m minimum focusing distance. I got the lens just before the latest version 1.10 firmware update for the K-7. Even then focus was quick enough but the new update seemed to improve on the focus lock. The interesting thing with this lens is that it is SDM only, which means older Pentax DSLRs (K100D/K110D and earlier) that lack the SDM contacts on the lens mount can only focus manually. Tried it on my old IR-converted *istDL2 and it took awhile to mentally switch gears to get used to this. It works fine in all other respects and it is IR friendly too, showing no obvious hot spotting on my IR images.

Much as there's plenty to like with this lens, sadly I just don't see many local Pentax users locally using it, which is a pity. In the context of many other third party alternatives in this zoom range and even Pentax's own DA* 16-50mm f/2.8 which is weather sealed, there is stiff competition. One issue could be price but I rather suspect the general uncertainty that's been generated on the internet surrounding the sudden failure of a few lenses with SDM motors has got to do with it. To me the SDM motor issue has been amplified by a small minority of vocal disgruntled users than actual numbers seem to suggest. So perhaps buying an extended warranty for SDM lenses as insurance might be a good idea to dispel the cloud of uncertainty. This issue aside, there's plenty of reasons to like this lens. Not too expensive, a good zoom range, great for portraits, a constant f/4 maximum aperture and it delivers sharp pictures... all very silently of course.

The photos here were shot during our monthly Pentax user outing at the Cafe Colbar in Wessex Estate off Portsdown Road. It was simply refreshing to experience the rustic feel of a place which is so different from the urban side of Singapore. Certainly having other Pentax friends for company definitely made it a memorable outing.