I've always loved shots that do something a bit out of the ordinary, and this scene from Pulp Fiction features a great example of split focusing, with Bruce Willis in the foreground in focus at the same time as Ving Rhames in the background.
So i've been continuing to add to my collection of camera gear, and my latest ebay bargain is a used but as new split diopter filter, which is perfect for exactly this kind of shot.
I use a Cokin filter 'P' filter holder for my Canon DSLR, the Cokin range of plastic filters are easily the best value filters on the market and a great way to add value to your shots without breaking the bank.
The filter holder slides onto a ring mount (available for all lens sizes) and has a single filter slot which allows the filters to be rotated or raised/lowered.
The split diopter looks a little like a half magnifying glass, and slots into the Cokin holder easily, although it does exhibit some vignetting around the corners when using the lens at it's widest angle.
Here are a couple of shots that show the diopter in action, the first shot shows the scene with the naked lens. The camera is looking through a mirror back into the room. The bed is in focus but the frame of the mirror is soft.
This second shot shows the scene with the diopter in place, and the difference is immediately apparent. The foreground mirror frame is much sharper while the bed in the background remains in focus.
The downside to using one of these diopters is the visible edge of the diopter itself. There is always a clearly visible line of soft/sharp focus where the split needs to be hidden, in this case I've aligned it with the edge of the mirror frame, you can just see the blurred line above the starfish. In the Pulp Fiction example the line is hidden by the edge of the wall.
I'm pretty excited about how well this diopter works, and it's another useful tool for the camera bag, I still need a few more grad ND filters, and a mattebox to control flare.