Sigma has announced the new APO teleconverter 1.4x EX DG and APO teleconverter 2x EX DG for Sony mounts.
The new teleconverters are able to maintain the Hyper Sonic Motor (HSM) function of telephoto lenses such as Sigma’s APO 70-200mm F2.8 II EX DG Macro HSM and APO 50-150mm F2.8 II EX DC HSM while also increasing the focal length by a factor of 1.4x or 2x.
However, the HSM AF compatibility of course depends on the capability of the Sony SLR camera to support this function and on the maximum F number of the attached lens. If non-HSM lenses are used, focusing can be achieved in manual mode only.
Pricing and release dates to be announced at a later date.