So you would like to get more creative with your iPhone? The Beastgrip DOF Adapter MK3 has you covered. It is a full-frame lens adapter that lets you achieve a shallow depth of field. You can manually pull focus on your lens to add more depth to your videos.
The Beastgrip DOF MK3 works like a viewfinder of a DSLR camera. This version is designed to work with the latest smartphone cameras. It has a Canon EF Mount. You will want to use a fast lens ranging from f/1.2 to f/2.8. You can find this project on Kickstarter.