Canon EOS-1D X Mark III EOS-1DX Mark III Advanced User Guide - Page 836

C.Fn2 Safety shift If the subject brightness changes and the standard exposure cannot be obtained within the autoexposure range, the camera will automatically change the manually selected setting to obtain the standard exposure. [Shutter speed/Aperture] applies to < > or < > mode. [ISO speed] applies to < >, < >, or < > mode. OFF: Disable Tv/Av: Shutter speed/Aperture ISO: ISO speed Note When [ISO speed] is set, safety shift also applies to AEB shooting in < > mode. Safety shift overrides any changes to [Range for stills] or [Min. shutter spd.] from default settings in [ : ISO speed settings] if standard exposure cannot be obtained. The minimum and maximum limits for the safety shift with the ISO speed are determined by [Auto range] ( ). However, if the manually set ISO speed exceeds the [Auto range], the safety shift will take effect up or down to the manually set ISO speed. Safety shift will take effect as necessary even when flash is used. 836