I was shooting in manual with my camera (canon eos 6d) and a friend was shooting the same subject at the same time on the same settings as me (iso, shutter speed and aperture), but her images appeared much brighter on her viewfinder - any ideas why?
When you look through the viewfinder, you see the image through the widest aperture of which the lens is capable; and the wider the aperture, the brighter the image. If your friend was using a lens with a wider maximum aperture, her images would appear brighter. The settings at which the picture will actually be taken have no effect on this.
