this will show you how to zoom in on your iphone camera
it works on iphone 3gs, iphone 4, iphone 4s and iphone 5
it works with ios5 and ios6
in ios5 and later apple has hidden the zoom bar that was at the bottom in previous ios verions.
its easy to re-enable, just
in ios4 if the zoom bar is missing you need to touch the screen at the bottom for it to appear.