http://www.nikonchat.com/18-135-nikkor-lens-2/
I have a Nikon D80 with an Nikkor 18-135 lens. Can someone explain in lay terms what the 18-135 means?
I would greatly appreciate detail…
18-135mm refers to the focal length. Focal length is the distance from the optical center of the lens to the film plane, or in this case the digital sensor. 18-135mm indicates a variable focal length, which means a zoom lens. You are able to change the focal length from 18mm to 135mm.
18mm is considered a wide angle; 135mm is considered a telephoto. So you have a zoom range for an 18mm wide angle lens to a 135mm telephoto lens.
You also have a set of variable f/ numbers, probably f/3.5-5.6G. This refers to the widest aperature. Basically as you zoom the lens from 18mm to 135mm, you change the widest aperture from f/3.5 to f/5.6. The hight the number, the smaller the opening and the less light being let through the lens. The “G” means that there is no aperture ring on this lens, you adjust the aperture electronically through the camera.
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