Sigma has announced a firmware update that enables several of its E-mount lenses to be compatible with the maximum 120fps burst shooting rate of the Sony a9 III. Three lenses have been given the update:
• 50mm F1.4 DG DN | Art Ver.02 (Sony E-mount)
• 105mm F2.8 DG DN MACRO | Art Ver.04 (Sony E-mount)
• 14-24mm F2.8 DG DN | Art Ver.04 (Sony E-mount)
Read more: Sony a9 III full review
We were stunned by the a9 III and its incredible global shutter that enables 120fps full-resolution RAW continuous shooting, with no strings attached. Except that last bit was only true providing you were using the camera with a supported Sony lens - third-party lenses from the likes of Sigma were not compatible with the maximum 120fps burst shooting rate. Whether or not that was because of legitimate technical reasons, or just because Sony was intentionally restricting this stand-out feature for use with its own lenses, is up for debate. But now it is available with select Sigma optics, albeit still with a rather large caveat!
While these Sigma lenses are now compatible with the a9 III's 120fps mode, this is only when used in AF-S, DMF or MF focussing modes. You can't use AF-C; the very focussing mode you're most likely to want when shooting a continuous burst of stills. Granted, you'll still be able to track subjects moving across the image frame at a consistent distance from the camera, but you won't be able to maintain focus of a subject like a cyclist or racing car that's approaching you.
Of course it is plausible that only Sony lenses have the necessary processing ability to facilitate AF-C autofocus at 120fps. But on the other hand, Sigma is more than capable of producing world-beating optics with top quality AF, so we can't help but wonder if this is just Sony artificially reserving uncompromised 120fps a9 III burst shooting for use with its own lenses.
