Sometimes you buy technology and it works just fine but the DataVideo iPad Prompter as it stands won’t work with the Canon C300 without severe vignetting.
The problem lies with the camera itself, it’s too high and brings the lens far to close to the top of the 45˚mirror and on a 17mm lens the top part of the mirror assembly and the sides interfere with your picture.
The answer is to lift the mirror assembly 32mm above the base plate.
I took off the end bit of plastic as I have no use for it as it was the same thickness as the baseplate which the mirror assembly slides onto. Cutting it to 60mm as shown above you need to have a clear 40mm in order for the mirror assembly to slide onto.
You then need to drill two holes to hold the mirror assembly, to get extra height I used 3 nuts as shown.
Before the extra height is added the black shroud runs across the top of the lens and is too high up the mirror to allow a wide shot. After the re-engineering as you can see the extra 32mm brings the lens down to just below the centre point allowing you to use a 17mm wide shot.
After the upgrade and using one of the first iPad 3 tablets from Apple, it’s always better to be prepared before you hit a busy spell when time for reverse engineering would become a nightmare.