The FocusMaker might look like a protractor for your camera, but it’s actually an easy to use follow focus system. When shooting video, you’re likely to have multiple focus points. A follow focus system allows you to set “stops” at those points so that you can quickly move back and forth. via Cool Hunting
The D810 is the world's highest technical performance DSLR ever for outdoor, nature, reconnaissance, landscape, espionage, intelligence gathering, fine art and many other kinds of precision high-resolution photography.