Canon EOS R6 Advanced User Guide - Page 771

C.Fn2 Same expo. for new aperture The maximum aperture value may decrease (the lowest f/number may increase) in < > mode (manual exposure shooting) with ISO speed set manually (except when set to ISO Auto) if you (1) Change lenses, (2) Attach an extender, or (3) Use a zoom lens with a variable maximum aperture value. This function prevents the corresponding underexposure by adjusting ISO speed or shutter speed (Tv value) automatically to maintain the same exposure as before (1), (2), or (3). With [ISO speed/Shutter speed], the ISO speed is automatically adjusted within the ISO speed range. If exposure cannot be maintained by adjusting ISO speed, shutter speed (Tv value) is automatically adjusted. OFF: Disable ISO: ISO speed ISO/Tv: ISO speed/Shutter speed Tv: Shutter speed Caution Does not respond to changes in effective aperture value from changes in magnification when macro lenses are used. Cannot provide the same exposure as before (1), (2), or (3) if [ISO speed] is set and the exposure cannot be maintained at speeds set in [ISO speed range]. Cannot provide the same exposure as before (1), (2), or (3) if [Shutter speed] is set and the exposure cannot be maintained at speeds set in [ : Set shutter speed range]. Note Also responds to changes in the highest f/number (minimum aperture). The original exposure setting is restored if you perform (1), (2), or (3) with [ISO speed], [ISO speed/Shutter speed], or [Shutter speed] set and do not adjust ISO speed, shutter speed, or aperture value before returning the camera to the original state, before (1), (2), or (3). Shutter speed may change to maintain exposure if the ISO speed increases to an expanded ISO speed when [ISO speed] is set. 771