If you would like your weekend soccer-match images of the kids to look more like Sports Illustrated than just a regular snapshot, you need to understand the benefits of using various lenses.
There are three important things you should know about lenses.
1. Focal Length – Different lenses provide different perspectives, and what makes those lenses different is their focal length. Focal length can be thought of as the amount of a lens’s magnification – the longer the focal length, the more the lens maginifies the scene.
Here is a picture taken with a normal 50mm with a maximum aperture of f/1.4. This lens is called a standard or normal lens because 50mm approximates the perspective of the human eye, maintaining the spatial relationship of objects in your image very closely to the way you see the world.
Canon Normal EF 50mm f/1.4 Lens (Prime)
Here is a picture taken with a telephoto 70-200mm lens. I like to use a telephoto lens for portraits because it provides a flattering perspective and allows me to isolate my subject from the background. The spatial relationship in my scene is flattened, so noses don’t look larger than normal, and a long focal length combined with a wide aperture helps me blur out the background behind my subject.
Canon Telephoto EF 70-200mm f/2.8L IS Lens (Zoom)
This picture was taken with a wide-angle 16-35mm lens. A wide-angle lens exaggerates the spatial relationship of objects in your image – it’s fantastic for capturing the interior of a room or large, expansive environmental portraits. Besides including a wider field of vision, a wide-angle lens is shorter than a telephoto lens and is capable of rendering a deeper depth of field. This lens is a favorite with landscape photographers who intend to capture detail from the foreground to the background of their images. Be aware that anything close to the wide-angle lens appears a good deal larger than life. Often not a flattering perspective for portrait photography, but some very interesting effects can be created by shooting with a wide-angle lens in close proximity to your subject.
Canon Wide Angle EF 16-35mm f/2.8L Lens (Zoom)
2. The difference between ZOOM and PRIME lenses.
Zoom lenses – Zoom lenses have a range of focal lengths (ex: 24-70mm), and allow you to quickly increase or decrease your lens focal length, including more or less of your scene in seconds, without changing your physical distance to your subject.
Prime lenses – Prime lenses have a single focal length (ex: 50mm), are generally less expensive than zoom lenses and produce sharper images but you miss the convenience of quickly changing your focal length with one lens.
3. Lens Speed – A lens with a wide maximum aperture (ex: f/2.8) is considered a “fast” lens because more light passes through the lens, allowing a faster shutter speed. A lens with a smaller maximum aperture (ex: f/5.6) is “slow” because less light passes through the lens and requires a slower shutter speed. This is an example of when a faster lens can really make a difference – capturing the action of a subject in motion.
Taken at ISO 100; f/4; 1/640 sec., with a Canon EF 24-105mm f/4 L IS Lens.
Most basic, inexpensive zoom lenses have a variable aperture of approximately f/3.5-5.6. This means the lens speed/aperture changes as you zoom closer or farther away from your subject with the wide or telephoto capability of your lens. These lenses are wonderful to use when beginning your photographic journey and are capable of producing excellent images, but they do have limitations. For example, you won’t be able to shoot hand held in most low-light situations – you can only capture the action in bright light or by using a flash – and rendering a very shallow depth of field is not attainable. The following link will guide you to a good quality but affordable walkaround lens with a variable aperture, the Canon EF 28-135mm f3.5-5.6 IS Lens. This is an upper-medium grade consumer lens with image stabilization and a great focal length range.
If you can afford to spend more on a lens, check out the Canon EF 24-105mm f/4 L IS Lens. This lens features a reasonably fast widest aperture setting of f/4 which remains constant throughout the zoom range, and the Image Stabilization (IS) provides an additional 3-stops of hand-hold-ability (definitely my favorite feature of the 24-105 L)
I hope this brief overview on lenses has been helpful. If you’d like to learn more about lenses, equipment, lighting, composition, and taking better pictures of people, check out my book Portrait and Candid Photography.