To demonstrate how useful graduated filters are I have taken the shots below.. For my first test, I found a room that was lit by a window on one side. I set my camera on a tripod and aimed the lens at a wall perpendicular to the window. The window is on the right hand side in my shot.
No Filter
We can see that without the use of a filter the right hand side of the shot is lighter than the left.
Graduated Filter
Keeping the shutter speed and aperture the same; applying a graduated filter so that the darker half is on the right and the soft edge is vertical evens out the exposure across the wall.
Next, correctly exposing a shot for landscape will leave the sky very bright, we can see an example of this in my first shot.
No Filter
To counteract the bright sky problem a graduated filter can be attached to the lens.
Graduated Filter
Again the shutter speed and aperture need to remain the same. With a filter attached, it should be positioned so that the darker half is placed over the sky and the soft edge is slightly above and parallel with the horizon. This should help to both correctly expose the sky and the landscape.
