I just got my Canon EF 50mm F1.4 USM lens for my Canon T2i and I'm shooting in video mode but the F-Stop shows 5.6 with the video being dark and it won't let me change the F-Stop to F1.4 or any other.
My Shutter Speed shows 1/60.
Can someone please tell me how to change the F-Stop?
Thanks in advance,

Zia

Menu > Video 2 > Movie Exposure > Manual

See page 127 of the operator's guide for more detailed information on this procedure.

the way i do it while in video mode is hold down the AV button and turn the dial at the same time