Photo tips for watery bloggers -- Focal length

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Focal length can be approached two ways -- how much angle of coverage the lens is able to record and how much visual distortion or compression is evident in the final image. Both are important for how they impact a photograph.

The shorter the focal length (10-30mm), the wider the angle of coverage, the more the image appears to be distorted and the greater the depth of field.

16mm focal length

The longer the focal length (70-210mm and above), the narrower the angle of coverage (and the higher the magnification), the more the image appears to be compressed and the shallower the depth of field.

500mm focal length

Focal lengths that approximate that of a human eye -- 35-70mm (depending on a variety of factors) -- deliver results we are most accustomed to seeing and relating to from our own vision.

50mm focal length

One area where focal length is very important is portraiture and a very good visual representation of how focal length affects the rendering of a portrait can be found here, here and here. One of the best tools I've found online for seeing what different focal lengths can do can be found here; it doesn't show what the effect of focal length is upon image distortion or depth of field, but it's good nonetheless.

For use aboard watery environments, I find that the shorter focal lengths work best for getting larger amounts of the scene, especially when I'm shooting subject matter aboard our own boat. However, when trying to take shots of other peoples boats out on the water itself, the longer focal lengths deliver better results.

The take away here is that you'll need a wide range of focal lengths if you want the best results, and many of the current point-and-shoot cameras have a built-in zoom lenses that can cover quite a bit of what you might want.