New research shows that Apple doesn't just want to protect iPhones from water damage, it wants them to take perfect photos while in that water.

There have long been third-party accessories that make it possible to film underwater with an iPhone. But as Apple itself notes in a newly-granted patent , such devices came with a specific problem.

"When capturing images underwater, typically the camera system must be protected from the water," says Apple in the "Plurality Of Optical Centers In A Unified Free Form, Hemispherical Optic" patent. In certain cases, "a barrier specific to the lens may be provided, for example in the case of a dome port."

But putting these in front of the lens is a balancing act.…