Well, It does Depend. Typically I'm in Av mode unless I'm using an M type lens. On the K5 for quite some time (and always had my K7 set this way) I had ISO on the front e-dial and shutter speed or aperture (for Tv or Av) on the rear dial. With that, I could change ISO on the fly to suit and simply hit the green button (in those modes) to go back to Auto ISO. I can easily flip to Tv and use it the same way. Now, I have EV Comp on the front dial for those modes. Since I've discovered using it, I found myself doing a lot of button pushing (well, one button) to change EV Comp and as a result was missing my shots. I typically keep the K5 at ISO 80 but sometimes I'll let it fly auto between 80-32000.