Ways to Eliminate Backscatter
Filed Under Tips & Techniques |
If you’ve been diving with a group, exploring a swim-through or tunnels, or else meandering along the bottom, you know that unless you’re first in line, it’s likely that the divers preceding you have already stirred up sand or silt or whatever is on the bottom.
Should you be thinking of taking pictures, it can be nearly impossible to get clear shots in this situation due to the lowered visibility. Over time, we learn it’s best to be first in line, or go without the group.
That is the most obvious form of backscatter, but even when no one has stirred things up, you can have a similar problem when photographing underwater.
Just look at this shot of a sunken tug to see what I’m talking about. This happened despite good viz due to the tiny particles in the water. These may be organic or non-living, but either way cause difficulty.
The reason is because the bright light from a strong flash aimed directly at the subject can catch these particles and be reflected back, which will blow the shot. It looks like snow due to the halo effect around each particle. And the closer the particle, the larger the snow.
This snow or backscatter can often be eliminated or reduced by preventing the flash or strobe(s) from firing directly at the subject. One way is to use a flash diffuser to soften and disperse the light from the camera’s built-in flash and lower its intensity. This is how the vase sponge shown here was captured.
Another way is to disable the cameras built-in flash and use an external strobe, or strobes, that can be positioned above or to the side(s) of the subject. This way you get the illumination desired, but since the light doesn’t come from directly in front of the camera, it gets reflected somewhere else.
Related resources: Underwater Camera Store
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