Why Use A Standard Focal Length?

Tony Shapps tells us why we should try shooting with a standard focal length.

Posted: 12/08/2011 - 14:13

In this era of ‘zoom everything’ you might be forgiven for wondering what practical use is a standard 50mm lens (the modern day version is a 35mm lens on a Digital SLR - giving you a 50mm equivalent) and I would agree that this is a perfectly valid question.

So, what’s the answer?

Well, for many years prior to the wide introduction of zoom lenses, the prime - or fixed - focal length optic held almost complete sway. If you wanted to photograph something that was some distance away from you it was necessary to purchase a telephoto lens (incidentally the latter was actually a British invention by the Dallmeyer Company). Similarly, to get more of the subject matter into the picture required the use of an additional wide-angle lens.

The 50mm was the ‘norm’. So much so that people began to wonder if this was because it was the cheapest to manufacture; or perhaps some optical firm had found a secret hoard of suitable elements which kept the costs down to a minimum. None of this was true because a good standard lens was - and still is - capable of producing almost unequalled razor sharp image.

No, the real reason for using this focal length… even if you just set this on your zoom… is because it gives you a normal, life sized, 1:1 image. This means that if you were to look through your camera viewfinder with, say, your right eye, whilst keeping your left eye open, you would observe a normal stereo image (after all, we do naturally always see in 3D around us). The image size for both eyes would match. This way you will always get a natural looking picture.

Doing what comes naturally

Additionally it is actually easier on the eye particularly if, like me, you are fond of taking the odd stereo (3D) pairs. To do this you don’t have to own a 3D camera. Simply use the 50mm setting, or your digital equivalent, stand with your feet slightly apart, then lean on your left foot and focus that little centre square in the viewfinder on the most important part of your image, and take your first shot. Then lean on your right foot, line up again and take your second shot. Yes, it’s as easy as that.

You will have a natural looking set of two photos which, when properly viewed, will recreate the inherent depth of the original subject. There are a number of programmes that allow you to process and combine such images. The latter can be outputted in a number of forms, for viewing on a computer or printing as solid copy. For general computer distribution converting to red/cyan has become the most popular and viewing glasses with red/cyan filters are generally used these days because they retain much of the image colour.

So, if you have always tended to use your zoom lens like a trombone, why not forget this for a while and settle down for a short period using the standard lens setting and concentrating more on the art of composition? It makes a good exercise and, apart from that, is enjoyable.

Words and image by Tony Shapps.

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