According to the service notice, Sigma will be offering a free update service for customers owning recently manufactured Alpha-mount Sigma lenses. Customers are advised to contact their nearest authorized Sigma Service Station for further details. Understandably, Sigma does note that lenses that have been discontinued for several years or longer may not be covered by this update service.

The problem is one we encountered in our own lab testing of the Sony Alpha SLT-series cameras, in concert with the Sigma 70mm f/2.8 DG Macro lens, and appears to relate to a miscommunication between camera body and lens. (In our case, the same lens worked correctly on a traditional Sony DSLR body.). Sigma states that the lens aperture may not work properly, and possibly result in a "camera error" message being displayed on the SLT-series body. In our lab, we occasionally found that upon completion of an exposure, the 70mm lens' aperture would remain stopped down. On the subsequent shot, the lens would then incorrectly stop down even further from its previous position, resulting in an underexposed image. Pressing the Depth-of-Field Preview button a few times would generally clear the issue, perhaps providing a workaround for photographers occasionally wanting to use an older Sigma lens with an SLT-series camera, although there's obviously no guarantee that this behavior wasn't specific to our combination of lens and body.

As well as offering a fix for customers with recent or current lenses, Sigma has also noted that it will be implementing the fix in all new production of Alpha-mount lenses. This will be indicated on the outside of the packaging, with a sticker on the box stating "α33, α55 compatible."

For more details on the fix, visit the Sigma website.

In other news from Sigma, the company has announced that the Canon-mount version of its Sigma 85mm F1.4 EX DG HSM lens is due to start shipping at the end of this month. First announced at the Photo Marketing Association tradeshow last February, the 85mm F1.4 EX DG HSM has an optical design with eleven elements in eight groups, including one Special Low Dispersion glass element, and one molded aspherical glass element, as well as Sigma's Super Multi-Layer Coating. A sample photo gallery is available, showing seven images shot with the Sigma-mount variant of the same lens on a Sigma SD15 digital SLR.

Finally, Sigma has also announced that its 17-50mm F2.8 EX DC OS HSM lens will also start shipping in Pentax-mount form at the end of the month. This lens has 17 elements in 13 groups, including two “F” Low Dispersion glass elements, two glass mold elements, and one one hybrid aspherical element, plus Sigma's Super Multi-Layer Coating. Pentax-mount users should note that this lens only provides autofocus on bodies supporting in-lens HSM AF motors. It's also worth noting that this lens model continues Sigma's interesting tradition of offering in-lens stabilization on both Sony and Pentax mounts, which already include in-body stabilization. While the two systems can't be used simultaneously, it offers photographers a choice of whether they prefer to use in-body or in-lens stabilization for any individual shot, allowing the strenghts of both systems to be exploited. The Sigma 17-50mm F2.8 EX DC OS HSM lens was also announced at the PMA show last February, and began shipping in May for Canon and Nikon mounts, with Sigma and Sony-mount versions following last month. A gallery containing 14 images shot with the Sigma-mount variant of this lens on a Sigma SD14 camera body is available.