... not with my EOS lenses, though. I have an old Pentax M 50/1.7 lens and an f/2 from my mother's ME-super.
I bought a Pentax lens to EOS body adapter, and control the aperture manually (stopped down) on the Pentax lens. With the camera set to Tv-priority, and auto-ISO enabled, the EC control works fully and moves the ISOs up and down.
So, now, instead of having just two ISO biases for manual exposure with auto-ISO (0EC by default, and -1 with HTP for RAW), I have a 10-stop range, a lot more than I actually would need.
Isn't it so sad that you have to go out of the camera system to get such basic functionality?
These Pentax lenses have an aperture lever sticking out, and are dangerous with FF cameras, so to use on my 5D2 or 6D, I'd have to cut the lever and it's guard off, so as to not break the mirror.
