I have an upcoming trip to Hawaii and plan to attempt underwater photography while snorkeling.
Gear: Sony RX-100 with Ikelite underwater housing.
I have read varying opinions on the need for an external strobe. I have minimal experience with underwater photography. I don't have any SCUBA plans (only snorkeling) - do I need an external strobe?
Thanks, in advance, for your thoughts.
The RX100 does extremely well in low light. Most of the time you will probably be shooting at the wide angle end of the zoom range where the aperture is f/1.8, so there should be no need at all for flash at snorkeling depths. I have used several small Canon cameras in UW housings with very good results. I have tried the on camera flash on a few occasions, but it did not help much.
I have the RX100 now and hope to get a housing when the prices come down.
I have gone to Maui two to three times a year for the past 14 years. I have owned a Canon SD550 with the Canon UW case; a Canon G9, with the Canon UW case; and the Canon 95s, with the Canon UW case. I have also had two Nikon point & shoots (took both below 10', cracked the cases and fried them both. I'm a slow learner). I also had two Canon P&S's (not that impressive). I had a Sea & Sea with a single srobe attached (not sufficient light). And, I have had two Nikonos IV's (as I said-slow leaner). The Canon G9 required only 1 weight plate to be neutral bouant. It took fantastic pictures, with and without the on-camera flash. The 7MP SD550 Elph and Canon case took such steller images, with and without the on-camera flash, that I bought the 95s and a Canon underwater case. One thing I learned from using all this stuff is that "light" is always the issue. If you are planning to go below 10', you probably need a double strobe set up. The single strobe that was on the Sea & Sea I had was never enough to get a decent picture. However, it was a "film" camera. It could only be set to a 400 ISO maximum. Thus, it was very limiting. But, digital cameras are different. Above 10', the auto ISO feature of the canons allowed me to take unlite images most of the time. Sometimes, I find even the small flash on the 95s will wash out an image if I am too close. The auto ISO feature on digital cameras will almost always bring the ISO up to the point where you can get a great picture-so long as you (1) are above 10'; (2) take pictures in clear water (not after a rain); and (3) take pictures when the sun is high. The white sand bottom that's prevelent in Hawaii helps a lot, as well.
Not a diver myself, but did work on some friends pictures. From our discussions:
1) useability of strobe depends on clarity of water. If lots of particles in suspension, not much use (like shooting strobe in fog).
2) try to keep distance to subject to a minimum: a "thick" layer of water will alter quality (sharpness + color). Again, all dependant of how much particles in suspension (seen fantastic - professional - movie of diving under the polar ice cap with excellent clarity)
3) depending on how deep you'll be when you take the picture, the color cast on the pictures can become important. Water absorbs red radiations more than blue ones, so you'll generally end up with a blue color cast. Can be (at least partially) corrected in posttreatment. Strobe can help to lower the color cast.
An example of correcting color cast in post:
Have a nice trip!
I think the basic answer is that you don't usually need a strobe for snorkeling photography (well, at least at the start).
If you are photographing at depths that many of us snorkellers do ie rarely deeper than 5 metres, there is usually tons of ambient light so no flash is necessary.
Even when fish or critters are under ledges or coral overhangs there is still quite a bit of ambient light so the camera's flash is fill-in more than the dominant light source.
Now, snorkelling at night is great fun and can produce some neat pics. In that situ I suspect a strobe would really help. Having said that, I've found that relying on my buddy's use of their torch produces some lovely effects without a strobe.
Hope this helps.
Cheers - Errol