[h0001244]

Very good question ! ! ! !
When Sigma OS lens plugged on Sony Camera, that will be the case.
So far not much people talk about this yet.
But engineers suggested that both system may not be synchronizing together that leads to reduction on anti-shake capability. So switching off one system may be required. If both system can perfectly synchronizing together, then you will have may be 4-6 stops slower shutter speed.

[bzboy]

turn off your body anti-shake when using the Lens.

[叮噹仔]

呢度係"Canon 單反討論區"

[九龍人]

係唔可以一齊防震的,鏡頭唔知機身做咗修正,機身又唔知鏡頭做咗修正,就會變咗修正過龍,原本左邊模糊變咗右邊模糊.
同埋防震係有個限度的,唔代表可以乜都唔理淨係按快門影相都清.好多人以為天涯鏡再加防震就天下無敵,點影都得.用Live view,Zoom到二百幾mm,光圈變細,低光又唔理,秒幾兩秒照影,坦白講六級防震都未必有用.

[SleepingIII]

Sigma的某些PK口镜头有OS，镜头的说明书说开启镜头防抖的时候应关闭机身防抖。