Seems too good to be true, but a new adapter now allows you to use any DSLR lens from either Nikon or Canon with your iPhone. Any DSLR lens can be attached to your iPhone: Telephoto, wide angle, macro, etc which allows for custom control over the depth of field and manual focus.
It comes with two loopholes on each end of the case to tie on a camera strap. Pretty neat even if it looks weird using this. It’s just $190 for either the Nikon or Canon version.