One of my favorite lenses for journalism and street photography is the wide to telephoto zoom. Now we can shoot everything from landscapes to portraits with just one lens. However, there are times when you need a prime “normal” lens to capture exactly what your eyes are seeing. Most of us can adjust our zooms to approximate what were seeing but it usually leads to a less than desirable result.
We know that most modern cameras get the focal length from the electronics within the lens, however, most cameras do not display this information until after the shot. We also know that all lens manufacturers display some type of focal length information marked on the zoom ring. Most of these markings are only approximations of the true focal length and do not take into account the crop-factor of dx type sensors. So how can we be sure our lens is set to a “normal” focal length?
An easy solution is to calibrate your lens to your eye. You are probably thinking, “How is this possible”. We can do so using the same method we use to focus your fathers trusty pair of binoculars.
Calibrating your lens is simple. First, find a suitable static target to focus on. With both eyes open, adjust your camera so that one eye is looking through the viewfinder. Focus your lens at your target as you normally would.
Now, with both eyes open and focused on your target, slowly rotate your zoom ring until your image is sharp and your eyes no longer feel strained. Refocus your lens if necessary and repeat the procedure. You will get to a magic point where your focus and depth perception are “normal”.
At this point, you should be able to remove and replace your camera from your eye with no apparent change in your target. Your lens is now calibrated to your eye. You can optionally create a small mark on your zoom ring that corresponds to the mark on the body. Later on, when you need a “normal” lens, just rotate your zoom ring to that mark, and voila.
Gary C. Millwater has been a freelance photographer since 1976. Originally from New Jersey, he has traveled all around North America, Mexico, and the Bahamas looking for that next great shot. After moving to Florida in 1987, he was forced to trade in his lenses for a “real job”. He now shoots just for the fun of it. His non-published work can be seen at millwater-photography.com