Welcome to part 4 of our Photographer Know-how guide. Today’s entry covers camera lens basics and the different types of digital camera lenses available today. Click here for part 3, which discusses image sensors, here for part 2’s guide to pixels, and here for part 1’s roundup of different camera types.
Focal lengths and Lens Ratios
A camera’s focal length is the distance between the image sensor and camera lens when a subject is in focus, and is typically given in millimetres. Both the minimum and maximum values are given, e.g. 18-55mm. Shorter focal lengths offer greater field of views at the expense of magnification, while longer focal lengths provide stronger magnification but shorter fields of view. Camera lenses are available with either fixed (single) focal lengths or zooms, which offer a number of focal lengths.
The lens ratio refers to the camera’s maximum aperture of the lens, which determines how much light is transmitted through the lens to the image sensor. This information is found on the front end of the lens in a ratio format i.e. 1:2.8-4, and is known as the f-number. Lenses with low f-numbers are often used for nature photography and portraiture as such lenses are suitable at capturing images in low light conditions and can achieve a very shallow depth of field.
Types of Lenses
There’s a wide variety of camera lenses out there, so it’s a good idea to familiarise yourself with what types of photography the different lenses are used for. Some of the most commonly used digital camera lenses include:
- Standard: street and documentary photography
- Wide angle: landscape and architecture photography
- Portrait: head and shoulders (portrait) photography
- Telephoto: sports and wildlife photography
- Fisheye: panoramic and hemispherical photography
- Macro: still-life photography of small objects
Make sure you check back with us next week, when we’ll be talking about camera accessories and how they can improve your shots.