I am always looking for new strategies and technology to use to engage students into the lesson. For my last depth of field lesson, I used an app for the iPad called DSLR Remote HD. This app allows you to view, remotely fire, and control the various features on a DSLR camera.
When teaching this lesson, I only had access to one Canon 5D Mark II and one iPad 2 device. For that reason, I used the app to assist the students in understanding how the aperture, shutter and ISO affect the exposure, but more importantly the depth of field.