Digital Camera Buying Guide - More Basics

These are features of intermediate level to high end cameras that allow to control things like shutter speed, aperture, ISO equivalent and white-balance. All digital cameras have at least one automatic mode which lets the camera guess the best settings when taking a picture. Most medium or larger cameras have at least some manual controls.

Aperture

Aperture refers to how much light a camera can let in at a given shutter speed. A larger aperture, denoted by small numbers such as F2.8, lets more light in then a small aperture, denoted by larger numbers such as F8. Aperture also affects the distances that appear to be in focus when a picture is taken. This is called depth of field (DOF).

Shutter-Speed

Shutter speed is the duration for which a camera can record light to take a single pictureFast shutter speeds give a camera the ability to clearly capture objects in motion and take good pictures in very bright light. Slow shutter speeds give a camera the ability to capture detailed pictures in low light.. The shutter speeds of a camera are described as a range measured in seconds and fractions of a second. For example, if the shutter speeds of a camera are 1/1000 to 4, then it can take pictures from 1/1000th of a second to as long as 4 seconds.

Films for traditional cameras come in different sensitivities to light. The ISOs of a digital camera refer its equivalent sensitivities. A higher ISOInternational Stantdards Organization, organism that defined how film sensitivities are measured. rating means more sensitivity to light but produces pictures with more noise which is similar to pattern of film grain.

The focal length is a measurement determined by a camera's lens. When measured in 35 mm film equivalent, it serves to determine the angle of view of  pictures taken. The smallest the equivalent focal length, the wider the angle of view and vice-versa. Optical zoom is the ratio between the longest and the shortest focal length. For example, a lens that is 35-105mm has a 3X optical zoom, so does a 50-150mm lens. The difference is that the 35-105 equivalent lens sees wider, the 50-150 sees further. Depending on the subject, focal length may be more important than optical zoom. Photographers of architecture typically prefer lenses with shorter focal lengths.

Focal Length Multiplier

When a lens is mounted on a DSLR, it shows a different angle of view than it would on a 35 mm film camera. The focal length multiplier, sometimes called crop factor, is the ratio between the focal length of the lens and the focal length of a lens which would give the same field of view on a 35 mm film camera. The focal length multiplier is used to determine the angle of view of a lens on a DSLRFor example, a focal length multiplier of 1.5 makes a 28 mm lens have the same field of view as a 42 mm lens on a 35 mm film camera..

Normally, digital cameras focus automatically before each picture is taken. This is called autofocus. Digital cameras can also have a manual focus mode to manually select the focus distance. Manual focus is useful in situations when the camera cannot properly focus automaticallyTypically when the subject is too dark, low contrast or reflective. It is also useful to take pictures fasterNo need to wait for the camera to focus when the subject distance is known. Instead of manual focus, some cameras have an infinity focus mode which sets the focus distance to infinity, others have a pan focus mode which sets the closest focus possible so that everything beyond that point is acceptably sharpThis is called the hyperfocal distance.

All digital cameras can store their images in the JPEG format. The JPEG file format is designed to keep file sizes manageable. When used at the highest resolution and highest quality settingAlso know as the lowest compression ratio., the resulting images of excellent quality. For advanced needs, come cameras store their images in a file-format called TIFF. This is a much larger format which preserves very slightly more information. Some digital cameras may also store RAW data intead of an image which is then converted on a computer into an image using specialized software. This is useful when one wants to create images with a different look than what the camera can produce.