Beginners Guide to Focal Lengths
Focal length can be a strange concept when your first start out in photography. Those seemingly arbitrary numbers labeled on a lens, usually in millimeters. However, once you learn the principles behind focal length, the information can teach you on a number of levels from how wide-angle or zoomed in your image will look to shutter speed and what the effects of each focal lengths are on an image.
What Is Focal Length?
From a technical standpoint, focal length is the distance from the point where light converges in a lens to the image sensor or film plane. This affects how wide-angle or zoomed the subject looks.
The smaller the number in millimeters means a shorter the focal length, and larger the number in millimeters means a longer the focal length, For example, at 24mm, an image looks wide-angle and less zoomed in, while at 200mm, the image looks more zoomed in. Wide-angle = smaller numbers, zoomed in = bigger numbers.
As the numbers change, the angle of view changes. That is why this focal length is always quoted with a lens. For example, an 8mm lens or a fisheye lens can have a nearly 180-degree angle of view, while in a 400mm lens, the viewing angle is much more narrow.
