BetterPhoto Q&A
Category: New Answers

Which wide lens for pet portraits??

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February 18, 2007

Distortion in portraiture, be it human or pet, is caused by shooting in too close. The countermeasure is to step back and shoot from a distance. Pet portraiture is not as demanding as human photography as to distortion. This is true because unlike a human subject, animals don’t criticize.

While it is not necessary to use any particular lens focal length to avoid distortion, it is necessary to step back. Since it’s a natural tendency to compose in the viewfinder, portraiture is best served when a longer than normal lens is used. You see, the longer lens forces the photographer to step back as he composes. It’s a truism that it’s the elongated camera-to-subject distance that does the trick, not focal length.

As a rule of thumb the ideal focal length for portraiture is about 2.5 times the normal. Normal is a lens about equal to the diagonal measure of the film or chip format. As an example, the 35mm film format has a diagonal measure of about 42mm thus 2.5 times this distance is 105mm. If you heed the advice of experts, you would use a 105mm or longer when shooting portrates with a 35mm. I am telling you this because the 35mm film camera is the de-facto standard and thus most of the textbooks and teachers lecture using this benchmark.

Now your D70 sports a smaller format than 35mm film. In fact it is about 66% of the size of a 35mm frame. That being the case you can calculate portrait focal length counterpart needed by multiplying 105 times 0.66. Thus 105x0.66= 69.3 -- round to 70mm. Some prefer to divide by 1.5 which works out to be the same value as 1.5 is the reciprocal of 66%.

Distortion is all in the eye of the observer.

Luck and don’t get bit!

Alan Marcus
ammarcus@earthlink.net

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February 18, 2007