Will you be using Scuba? Are you a certified diver? These are the first questions that popped into my head.
I've shot a good chunk of underwater photos and video. The issues you will encounter are very similar to that of a still photographer. If you Google 'underwater photography" you'll find many resources. Amazon should have many books on the subject, as well.
An underwater work environment is extremely challenging. Things that seem easy to us on the surface, are sometimes impossible when diving. You are wise to do some research.
Things to think about (but by no means a complete list):
Safety! I'm a dive instructor, and one of my outings turned into a life-threatening situation within the first 30 seconds of the dive. I was loaded with video gear, a light, and a spare tank (thank God). Frankly, I was damn lucky to survive the 20 minutes that followed (I still squirm when I think about it). Please use caution. Even shooting in a pool can seem deceptively safe.
- Water/weather conditions. (safety)
- Water/weather conditions. (look & lighting)
- Water clarity.
- Since every shot is handheld, surge & surface waves can make framing a shot very hard.
- Depending on your camera housing, your viewfinder may be difficult, or impossible to see.
- Camera controls generally set on the surface, prior to entering the water.
- If the housing leaks, the camera is ruined.
- No rack focus. Auto focus can be very easily fooled by refraction and ruin your shots.
- The distances as written in your focus ring are NOT VALID underwater.
- Generally, I aim for maximum DOF, and shoot hyperfocal.
- Refraction will distort and magnify your image. You MUST familiarize yourself with this phenomenon before you try to shoot, because you can easily end up with useless footage.
- Chromatic Aberration.
- Plan and rehearse everything with the camera & talent while on dry land. Once you are in the water it's much more difficult to make your needs known.
- Anybody using dive gear must be a certified diver.
- Learn proper breathing techniques for cinematographer.
- Learn proper swimming techniques for cinematographer.
- Never allow a non diver to breath from a scuba system.
- Communication while submerged is difficult but not impossible if you rehearse your signals before you dive.
- Water absorbs light. So without providing artificial lighting, you will end up with blue-ish footage. This is why underwater photographers always use a flash. The further the talent is from the camera, the cooler (blue) they will be. Since the red wavelength is simply not present, there's no easy way to correct this with color grading. - Shoot with a wide lens, and keep your subjects closer to camera. - There is also an underwater CC filter than can help reduce some of the blue tint caused by light absorption.
** Plan on re-shooting everything later that day. Trust me on this; after you wrap you'll sit down and review your shots and discover something you either forgot, screwed up, or could have done better. If the cast & crew are already expecting to go back in the water, they won't hate you for it.
Research, plan, rehearse, shoot slowly & deliberately, expect to reshoot, and don't get hurt.
Thomas.
