Hello all, I am hoping someone may have any idea about this. I am looking for a company that can make a custom focusing screen for canon 5D Mark II and III. What I am after is a 10x8 constraint proportion box (and possibly other size constraints) to be visible when looking through the view finder so that the photographer can frame and shoot knowing exactly that the subject matter will fit into a 10x8 size constraint when cropped in post. I can find many companies that make a vast array of different focusing screens but none that allow you to specify what it is you exactly need. Any help would be greatly appreciated.