Basic Lens Components

Mount
Indicates what lens mount the camera has.

Aperture Ring
Controls the amount of light reaching the film or light sensor. Cameras that don't have an aperture ring often have an electronic control to adjust the aperture.

Depth of Field Scale
Indicates how much of the subject will be in focus.

Focusing Scale
Indicates the distance from the subject.

Focusing Ring
Used to focus on the subject when in manual mode.

Bayonet Ring
A threaded ring to attach filters.

Filter Thread
A threaded ring at the front of the lens for attaching filters.

Zoom Ring
For adjusting the focal length.

What is... "Stopping Down"?

"Stopping down" is when you decrease the amount of light reaching the light sensor by reducing the lens aperture. This will in turn increase the depth of field.

What is... Bracketing?

Exposure bracketing is a common technique that photographers use to make sure that their photos are properly exposed. This is particularly useful when lighting conditions are less than optimal. When you use exposure bracketing, you take 3 pictures of the same scene with different exposure, white balance and flash settings. One picture will be taken with an aperture and shutter speed combination that your camera deems appropriate to expose the scene. Another picture will be taken where the scene is under-exposed (negative exposure compensation) and the final picture will over-expose (positive exposure compensation) the scene. The under-exposed and over-exposed photos can be taken within a -3 to +3 stop range, represented as EV.

Conveniently, most SLR cameras have an Auto Exposure Bracketing (AEB) feature that will automatically take the 3 pictures for you. You simply set the EV value and the camera will take a picture that it thinks is properly exposed, a picture that is slightly under-exposed and a picture that is slightly over-exposed.

What is... Depth of Field?

Depth of Field (DOF) is the distance in front and behind the subject that appears to be in focus. DOF basically determines if your backgrounds are soft (blurry) or sharp (in focus).

Factors that affect Depth of Field:

• f-number: Increasing f-number (reducing aperture diameter) increases DOF (foreground & background are all in focus). Decreasing f-number (increasing aperture diameter) decreases DOF (soft/blurred backgrounds).
• Focal length of the lens: The smaller the focal length number of the lens, the greater the DOF.
• Distance: The greater the distance of the subject from the camera, the greater the DOF.
  A shallow DOF is ideal for photos where you want to call attention to your subject and not be distracted by the background, for example, portraits. A large DOF is ideal for landscape photos where you want everything in focus.

What is... Aperture?

Aperture is the diameter of the lens opening through which light is admitted. When the aperture diameter is increased, then more light reaches the film (traditional cameras) or image sensor (digital cameras).

Aperture is expressed as an F-stop. Here's where it gets confusing:
-The larger the F-stop number, the smaller the lens opening.
-The smaller the F-stop number, the larger the lens opening.

This takes some getting use to, but you need to remember that as the F-stop number increases, the lens opening decreases. Another term to be familiar with is a "fast lens". This refers to a lens with a large maximum aperture (small F-stop number).

A large aperture provides:
-Shallow depth of field (blurred backgrounds).
-Fast shutter speeds.
-Reduces camera shake.

A small aperture provides:
-Large depth of field (foreground and background are all in focus).
-Slow shutter speeds.