I know on PS3 I can enter and exit 3rd person mode with R3. If you hold down L3 while your in 3rd person, you can move the right anolog forward and backward to set the zoom on your 3rd person camera. I'm sure it's similiar on XBox but I'm not sure on PC.
Hope this helps.
It was the same with Oblivion on ps3 as well. On the zooming in and out is as easy as simply scrolling, so I don't think OP's on the PC.
Hmmm.. Good point. Thanks Chaka.
Either way, hopefully he hasn't already tried that and it is bugged.