It is extremely difficult to get a good photo of Hammerheads. They are very shy animals. As soon as they see an unknown shape, see or hear bubbles or see a light, i.e. camera flash or video light, they disappear into the ocean.
It is therefore critical for divers to stay together, not chase after Hammerheads, keep the light off and be as silent as possible.
When all the above is right you need luck or lots of dives !!!