What is a 12X or 20X Zoom Lens?

OK, first – quit thinking of it as a 12X or 20X optical zoom lens, that’s a marketing gimmick name and not really information a photographer or cinematographer can use. By itself, the information is worthless; it just means “20 times the zoom from its widest setting”.

Let’s use the Canon HD-20x zoom XL5.4-106mm L IS II (usually ships with the Canon XLH1s). The focal lengths on a that lens should be 5.4mm to 106mm – those are real numbers that a photographer/cinematographer can use.

Basically, at 5.4mm, your angle of view is extremely wide – which means they will be somewhat distorted (at 50mm, your angle of view is roughly that of the human eye). While 106mm is 20 times the zoom from 5.4mm, it doesn’t really mean anything except: 5.4mm, 10.8mm, 16.2mm, 21.6mm, 27mm, 32.4mm, 37.8mm, 43.2mm, 48.6mm, 54mm, 59.4mm, 64.8mm, 70.2mm, 75.6mm, 81mm, 86.4mm, 91.8mm, 97.2mm, 102.6mm, and 106mm (I counted in 5.4mm increments). And yes, they lied a little. It should be 108mm to be exactly a 20x lens.

So there you have it, a 20X zoom lens is a name from the “marketing sales gimmick department”. Look for the real numbers and do the math yourself to understand what focal lengths you are actually dealing with.

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