Sigma has issued a lens product advisory for its 60-600mm F4. 5-6. 3 DG OS HSM and 70-200mm F2. 8 DG OS HSM lenses. According to the advisory, Sigma has 'found a phenomenon whereby when pressing the shutter button on the camera body, it may occasionally stop operating and not respond to the reoperation.
Due to this 'phenomenon' (someone's been looking at Canon's product advisories), Sigma says it will offer a lens firmware updates free of charge to customers with affected products within the following serial number ranges:
Sigma 60-600mm F4. 5-6. 3 DG OS HSM | Sports for Sigma, Canon EF and Nikon F Mount
Serial No. 53824160 or earlier
Sigma 70-200mm F2. 8 DG OS HSM | Sports for Sigma, Canon EF and Nikon F Mount
Serial No. 53846990 or earlier
Sigma notes its USB Dock can't be used for this firmware update 'as it requires an adjustment to optimize each lens individually. ' So, if you're noticing your lens having this issue and it falls within the serial numbers, Sigma requests you contact an authorized Sigma subsidiary/distributor who will then direct you to take the proper steps to get the issue fixed. You can find a full list on Sigma's World Network webpage.
We spoke with a technician at Sigma America who said lenses that aren't experiencing the issue don't need to be sent in at the time and in the event a lens still under warranty does have the issue occur down the road, Sigma will still provide the firmware update free of charge.
Sigma has also noted that some products within the serial number ranges provided have already had their firmware updated. As shown in the above graphic, units with a black dot sticker above the barcode of the box have already been updated.. dpreview.com