How far?

A question I often get is how far different lenses can see. To answer that once and for all I give you a uncomplicated explanation here and now. The problem with a qustion like this is that you can't compare like that. All lenses can see just as far, the difference is the grade of magnification. A lens on a camera can't see any further than the lens of a human eye.

Let's say you stand on a beach and your eyes are 2 meters above sea level, then you can see approximately 5 kilometers and anything beyond that is under the horizon and gets obscured. The surface curvature of the Earth sets the limit. If you're higher up so your eyes are 10 meters above sea level you can see a little over 11 kilometers and at an altitude of 100 meters you can see almost 36 kilometers.

As the camera lens usually is at the same height as your eyes all lenses can see 5 kilometers when they are 2 meters above sea level and so on. This of course presumes that you have free sight, if there is a hill 3 kilometers away neither your eye nor the lens can see further than 3 kilometers.

How detailed the image will be however is deterrmined by the quality and resolution of the sensor in your camera, all lenses though can see just as far.

To illustrate the difference between lenses here are a couple of images, they're all shot at the same distance from the house, 45 meters, but with different focal lenghts (18, 50, 100, 300 och 500 millimeters)