Technical Tips for the UW Photographer

Technical Tips

I find that when I am underwater, enjoying my dive, there is just too much going on to fuss with all the dials on my camera. I'm watching my gauges, my buddy, and scouting for photo subjects, all at the same time.

When my subjects are fliting around, in and out of holes, by the time I finish making the settings perfect, my subject is long gone, and I'm still thinking about F-stops.

I find that I use two settings when I dive: "Low Light-Flash On" and "Good Light-Flash Off." I can make the transition easily enough and still keep from drifting off and becoming one of those divers you read about where the dive boat headed for home one photographer short.

Because of this, I am reluctant to buy a strobe or wide angle lenses, because they will just add to the clutter.

To Strobe, or Not To Strobe

With the MMII system, it's simple.

The f-stop dial gives you a choice ranging from 3.5 to 22. To make it easier, there is a little picture of a sun next to the 22, and clouds next to the 3.5. Pretty intuitive. When the setting is at 3.5, the strobe will flash. For even darker settings, you can set the shutter speed to 16 (on the same dial) and the flash will go off a little stronger.

With the MMII-EX camera, it's a little more complicated, because there are three dials instead of two dials:

Shutter Speed - (On top of the camera). Values from 15 to 125 and 125 w/ flash. Essentially, shutter speed controls how much light can get into the camera. I tend to keep the value on 125. If I want the flash, then I switch it over one notch.

If I am shallow, the subject is not moving, and the current or surge is not moving me either, then I'll change the shutter speed to a lower setting (like 1/60 or 1/30) to make use of the available light. The photos above give you an idea of the effect that shutter speed can have on subjects that don't move.

Aperture - For UW photos, I tend to just leave the aperture at f-5.6 or f-3.5 (with the cloud pictures). Then I just have to decide whether to use the flash or not.

The MMII-EX has a light meter to help you out. Push the shutter buton half way, and the light will glow red or green. If it glows red, then you don't have enough light. Switch the F-stop to a lower setting (more clouds), and try again. If it's still red, then you need the flash. The only challenge is whether the little flash in the camera is enough. Unless you are close to your subject, it's normally not enough.

When I get confused about f-stops, just think of your pupil. When it's dark out, your pupil gets larger to let in more light. Just like f-5.6 or f-3.5. When it's sunny, your pupil is at f-16 or f-22.

Here's where it get's confusing:
Ever notice how you lose depth perception at night? Ever try to judge distances at night with only one eye?
Your camera only has one eye.

If the aperture is wide open (f-3.5), then you have to be more accurate with your focus since your "Depth-of-Field" is smaller. Depth-of-Field is essentially the area where your subject will be in focus. Everything outside the field will be out of focus.

Say, you judge the distance to be 4 feet between you and your subject. Set your focus to 4 feet, and call that your "Focus Point". See the diagram to show how your Depth-of-Field is shortened by a wider aperture. You should also note that when you make your focus point setting, your Depth-of-Field extends 1/3 in front of your focus point, and 2/3 behind it. You always have more in focus behind your focus point, rather than in front. This is good, since you normally under-estimate distances underwater.

Focus - I find the focus to be very forgiving on the MMII cameras. You can only guess your distance to the subject, and find the relative distance on the focus knob. I tend to take pictures that are too far away for my own good, or else very close up. Either way, I'm rarely out of focus - probably because I always keep the aperture wide open. It's always a problem with light that ruins the photos. However, you have to pay more attention in low light situations when the aperture is wide open.

The basic principles you want to follow are:
F-stop as wide as possible (so your depth of field is big)
Shutter Speed as slow as possible (so you get the most light)

This all gets more complicated when you are dealing with 100 vs. 400 film. I normally don't worry all that much about it. Basically, I just decide, "To Strobe, or Not To Strobe."

The built in light meter helps with it's red-light/green-light function. However, I'm normally so busy fiddling the dials, that eventually I just ignore it and take the picture anyway.

Trouble Shooting

When dealing with the MMII system with it's built in flash, most of the problems can be attributed to the flash (or lack thereof.)

Biggest problem most of my photos have is "backscatter." Essentially, particles in the water are lit up by the strobe, and reflect back to the lens, making it look like you are taking photos in a snow storm. See the white squares in this picture of a porcupine fish. There are two solutions to this. The first solution to this is to get an external strobe, and angle it so that the reflected light is not going back to the lens. This is an expensive solution. The second solution, go to a better dive site.

There are two, much more affordable and practical solutions:
Get Rid of the Particles - Put less water between you and the subject. If you are closer to your subject, like a macro shot under 18 inches, then there are alot less particles between you and the subject. There is also more reflected light from other sources, so particles don't stand out.
Turn Off the Flash - With the F-stop at 3.5 and the shutter speed at 1/15 or 1/30, you are making the most of your available light. When in doubt, take your first shot with the strobe, and the second without. Poor man's bracketing.

Every other bad picture I ever took can generally be attributed to low light and too much distance between me and the subject.

Don't reach for your subject.
If it comes to you, shoot it.
If it doesn't, it was never meant to be in pictures.

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