A SLR mount attaches to the iPhone and will allow you to attach your high-quality lenses to the hand set. Expect much better zoom, depth of field, and other additions over the iPhone’s standard offering.
If you have some cash to spare, but not enough for a high-end DSLR, this stand should make your iPhone come close.
According to Engadget, you can pair your iPhone 4 with various “multi-thousand dollar” Canon or Nikon optics, thus “bringing ‘powerful depth of field’ and manual focus to your smartphone’s itsy bitsy image sensor.”
The iPhone SLR Mount is compatible with any iPhone and currently costs $249. There are two versions available and both cost $249. One is based on Canon EOS SLR lenses and the other is compatible with Nikon SLR lenses. You can purchase it from Photojojo Store here. The mount is listed to only be compatible with the iPhone 4 so far.