This may be a dumb question, but I'm playing with the C100 ii for the first time, just moving up from the DSLRs. I have a shoot coming up next week with it. Right now I have the 24-105mm lens on the camera. I can adjust exposure using the exposure wheel on the handle when I'm zoomed out, but when I zoom in, the F stop indicator changes on the screen, but the exposure does not actually adjust (I see the same brightness on the external monitor, viewfinder and OLED). Can this mean something is wrong with cam/lens? I am about to change lenses, but am waiting for a friend to come over to see if he can sort me out. Thanks.