Found today on Gizmodo: How Filmmakers Use Aspect Ratio Tricks in Movies
Rikk Flohr © 2016
When I finished the mockup of my latest concept I decided to crop it down to an 8×10 aspect ratio. To aid in composition, I used Adobe Photoshop Lightroom’s™ Crop Overlay for the Fibonacci sequence or Golden Spiral, to which it is sometimes referred. The Crop Overlay is accessed with the [ O ] key and cycling it several times will bring you to this overlay. [Shift][ O ] rotates the spiral through its eight possible incarnations. It becomes then a matter of working your crop to place a strong point of emphasis into the terminus of the spiral.
Rikk Flohr © 2013