One of the very first questions asked by newcomers to the Digital SLR world is, “What lens should I get?”. While I won’t exactly answer that question in this article, I will drop some knowledge that will teach you how to tell the difference between camera lenses. I’ll cover lenses designed for 35mm camera systems, since the most popular DSLRs are compatible with these kinds of lenses.
First, there are a few definitions you should know:
- Wide Angle Lens
- Wide angle lenses have an expansive field of view — they fit lots of stuff into the photo. For example, wide angle lenses are good for capturing wide, sweeping landscapes or large groups of people.
- Telephoto Lens
- A telephoto lens has a focal length that brings you up close to distant subjects. A telephoto lens might let you fill the frame with the batter even if you are sitting in the upper deck.
- Zoom Lens
- A zoom lens is one with a range of focal lengths. A zoom lens does not necessarily bring you close to distant subjects. This is a common misconception. Zooming is simply the act of adjusting the lens’ focal length in order to “zoom in” on your subject, or pull away.
- Prime Lens
- A prime lens is the opposite of a zoom lens — a prime lens has one focal length. If you wish to get close to or further away from your subject, you must physically move yourself and the camera.
OK, now on with the lesson. Camera lenses follow a systematic naming convention that includes the lens’ specifications in the name. The name of a camera lens is best remembered as being a formula. If you understand this formula, you can tell the difference between lenses by simply reading their names.
The Formula
[brand] [focal length(s)] [maximum aperture] [other designations]
The Ingredients
The brand tells you who makes the lens. It will be a manufacturer’s name, such as “Nikon”, “Canon”, or “Sigma”. The brand portion of the formula may also designate what sort of cameras the lens is compatible with. For example, “Canon EF” lenses work with all Canon EOS cameras, while “Canon EF-S” and “Sigma DC” lenses only work with cameras that contain APS-C sized sensors.
The focal length describes the lens’ field of view. If it’s a zoom lens, the focal length will read something like “18-200mm”. This means the lens is capable of utilizing all of the focal lengths from 18mm (wide) through 200mm (telephoto). If it’s a prime lens, it will only have one focal length, e.g. 50mm.
Aperture is the hole in the lens through which light passes. The maximum aperture describes the widest diameter to which this hole is capable of adjusting itself. A maximum aperture might be f/1.8, f/2.8, f/4, etc… Lower numbers let in more light, making faster shutter speeds possible.
Finally, other designations describe various other features of the lens. For example, a lens that can focus on extremely close subjects and make them appear life-size will say “macro”. Lenses featuring mechanisms that compensate for camera shake to reduce blur will have a designation that says so — Canon calls this IS (Image Stabilizer), Nikon calls it VR (Vibration Reduction), and Sigma denotes it as OS (Optical Stabilizer).
Examples
Canon EF 70-300 f/4-5.6 IS USM
This is a Canon lens for their EOS line of autofocus cameras. It has a focal length range from 70mm (moderately telephoto) to 300mm (telephoto). The maximum aperture at 70mm is f/4 and the maximum aperture at 300mm is f/5.6. It has an Image Stabilizer, and a USM motor for efficient automatic focusing.
Sigma 17-70mm f/2.8-4.5 DC Macro for Canon autofocus
This is a Sigma lens whose focal length ranges from 17mm to 70mm. The maximum aperture at 17mm is f/2.8, and the maximum aperture at 70mm is f/4.5. DC means it is designed for digital cameras with APS-C sized sensors. It is a macro lens capable of focusing on very close subjects. It is compatible with Canon EOS (autofocus) cameras.
Canon EF 50mm f/1.4 USM
This is a Canon 50mm prime lens for their EOS line of autofocus cameras. The maximum aperture is f/1.4, and it has a USM motor for efficient automatic focusing.
