Introducing the Frameline from Unsound Labs, the best method we've found for mounting a phone or other touchscreen device to a boom pole or other cylinder ranging from 1 - 2 1/4" in diameter for use in TV, film & video.

You can use it to monitor live video of the frame with video assist software, or other great companion apps made by various manufacturers.  

Product weighs approximately 6.5 oz and fits any size boom in either landscape or portrait mode, accommodating screen sizes 4.5 - 6.5" diagonally.