I have a Nikon D90 and would like to set the aperture to f/1.4 and the shutter speed to around 1/60, all while having the camera compute what ISO is required for the current light conditions. I am choosing these settings to get the most possible light without worry that an unsteady hand will cause picture blur due to movement.
I have the "A" setting where aperture and ISO are held and shutter speed varies as well as "Auto" where all three are set by the camera and it doesn't ever seem to choose f/1.4.