The app can be downloaded at http://dslrcontroller.com/ and enables any Canon camera with Live View to be operated from a tablet. The camera is connected to the tablet using a standard digital/usb cable and once connected the app recognizes the camera and opens like a huge viewfinder. Almost every setting you want to make can be done on the touch screen.
I could go on and on about the features but instead will just tell you about the difference it made for focusing. The scope was moved to Sirius, centered in the tablet screen, enlarged 5x, a slow turn of the Meade focus and done. We then slew to M42, took one 30 second exposure and were rewarded with the photo shown here.
I give the Canon DSLR Controller two thumbs up! In the words of Ferris Bueller "It is so choice. If you have the means, I highly recommend picking one up."