Is it better to use an ISO more than 200 for underwater camera use?

Question

I just bought an underwater camera and the suggested ISO is 200. THe camera has an internal flash but woudln't it be better to use a higher speed film to capture more light and color? Wouldn't ISO 400 or 800 better?

Answer 1

Depending on the type of film, the photos would probably start to get grainy at the higher ISO. You should probably experiment with some test film rolls to see what works best.

If this is an digital camera, you would be able to compare the different ISO settings while you're still on location and make adjustments as you see fit.

Answer 2

ISO 100 or 200 should be fine and ISO 400 can be useful for shallow depth of field. Avoid ISO 800 and above however, due to degradation of image quality. Save that grainy look for your night time street photography.
If you don´t have sufficient ambient light, add strobes. This shouldn’t be an issue if you’re just snorkelling, but for scuba diving a strobe is practically required equipment.

Answer 3

I guess it depends on how deep underwater you go. Deeper means less light, of course. I'd say for above water, 100 would be standard, and below water, 200. Deeper and dimmer would need faster film.

It also depends on how fast your lens is. If it's a really fast lens, like 1.4, it can handle the dimmer light better.

Careful going with a film speed too fast, though. With higher film speeds, you get more grain with film, and more noise with digital. Beautiful pictures of brightly colored fish in a nice aqua sea could be washed out by that. So save the higher speeds for deeper and dimmer.