Thursday, January 06, 2011

How to Record Video in a Tidepool

Here are some lessons learned from my recent tidepool filming efforts.
  1. Suspended sediment is your enemy. Tiny particles in the water act like fog, turning the movie into a hazy mess as they reflect sunlight from above. The first day I shot was right after a rainstorm and the tidepool was quite cloudy from runoff. The result was a wasted hour.

  2. Canyons are your friend. The PlaySport has a minimum focal length of 39.6", so you need a bit of distance between the camera and your target. A water-filled crevasse in the rocks is perfect, so long as the end you're pointing at is in sunlight.

  3. I shot entirely through as much sunlit water as I could and in retrospect that was probably a mistake. If there is no sunlight, the suspended particles have nothing to reflect and so they don't produce foggy, ambient light. Since the first 39" can't be made out anyway, you might as well shoot through 39" of shadow, so long as the scene you want to film is at least that distance away, is bathed in sunlight and you have a clear line-of-sight to it.

  4. Deep tidepools, the kind large enough to submerge the camera and give you 40+" of shooting distance, are not loaded with animals. For example, the hermit crabs are all hanging out in the shallow pools. That means that if you want to capture some critters on film, you need plenty of patience. The video below shows the last few seconds of film where a tiny fish popped into the scene (lower right-hand corner) just as I was pulling the camera out. I ended up missing the only real drama in the scene because I didn't wait long enough.

  5. You need two establishing shots to set the scene. First, you need a long-distance shot of the tidepools in general. Next, you need another above-the-water shot showing the layout of the tidepool you're filming. After that you can submerge the camera and get to work.


tim eisele said...

A thought: How about if you got a piece of large diameter opaque tubing (maybe a piece of 6" diameter black plastic sewer pipe a foot or two long?) and put the camera at one end of it? This would:

- Shade part of the light path from camera to subject, to get rid of some of the scattered light from suspended particles; and

- Make it easier to do some shooting from the top, with the camera out of the water (the tubing would eliminate glare reflecting from the water surface, and also suppress ripples;

It would need to be pretty large diameter tubing to avoid making it look like you are shooting through a hole, and would make the whole apparatus a bit more awkward, but the benefits might be worth it at least some of the time.

K T Cat said...

Brilliant idea! The other thing you could do is get a tarp, cut it to 39" long and just float it over the scene. That would shade the entryway to the camera.