Filler light in daytime UW photography

[Hintermann]

Reconsidering my earlier decision, I decided to continue using twin Ikelite Autoflash AF35 strobes after all for the 80 or so dives left before I retire. The battery compartment of the right strobe was flooded and Ikelite are looking at it to see if it can be repaired. If not, I'll get a new one; after all, I can sell it next year when I quit diving.

Right. One of the problems we all encounter in UW photography is that it is often not possible to get as close to the objective as we would like for a number of reasons - a fish swimming away, it is too big or in a crevasse where the diver cannot go. In such a situation, is there any mileage in using a video light as a filler to reduce the blue colour cast and to improve natural coloration of the coral, fish etc? The video light as a colour temperature of 7000K and has 10%. 50% and 100% setting whiles the strobes rate at 5700K each.

I am also thinking of replacing my focus light with the video light at 10% power for photography during night dives. The problem with the focus light is that it has a very narrow beam and unless it is aligned perfectly with the AF square it does not work properly and occasionally does not switch off during the flash as it is supposed to. The video light on the other hand throws out a very wide beam and completely covers the frame with only a slight zoom. Although it is not designed to switch off when the strobes work, I was assuming that the camera's light meter will read the torch's light as ambient light and adjust the flash output accordingly. The AF35's own output is proportional to that of the triggering flash and so they should also make the necessary adjustment.....I think.

 

[Storker]

Re the reach of your strobes: Have you tried shooting at your camera's fastest sync speed and opening the aperture as much as possible?

 

[Hintermann]

Re the reach of your strobes: Have you tried shooting at your camera's fastest sync speed and opening the aperture as much as possible?

That would be all manual, wouldn't it? I usually shoot in AP with max aperture but as it is only a compact, that option is limited.

 

[Storker]

That would be all manual, wouldn't it?

That would be the most obvious choice, but not necessarily.

Remember that while there are three parameters (shutter speed, aperture and ISO) that control ambient light exposure, only two of them (aperture and ISO) control strobe exposure. So, to maximize the ratio of strobe to ambient, you should shoot at the highest shutter speed your camera can sync at. That would mean opening up the aperture. So, you can get that effect in aperture priority, too.

I usually shoot in AP with max aperture but as it is only a compact, that option is limited.

Ah. You're already at max aperture? That makes it a bit more complicated. Still, if you can adjust your ISO speed higher, that would affect strobe and ambient equally. Then, if your camera can sync at a higher speed than you were originally using, your camera automatics should give you a faster shutter speed. Then you have to decide how much ISO noise you're willing to tolerate, and on a small-sensor compact that could be quite limiting. But it might be worth a try.

I asked my original question just to check if you had exhausted all possibilities, since I'd be quite leery of mixing a 7000K video light with 5700K strobes. If you're unlucky it could give weird effects, and color balancing mixed-temperature lights is often a major PITA. OTOH, if you're lucky, or if you convert to B&W in post, it might turn out quite OK. Only one way to find out, right?