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... AF Lock?

AF lock stops your camera from autofocusing after your subject is in focus. You should first focus on your subject and then recompose the shot.

What is... Aspect Ratio?

Aspect Ratio is the ratio of a picture's longer dimension to shorter dimension - or its length to width. 35mm film and most digital SLR's usually have an aspect ratio of 3:2 which can produce 6 in. x 4 in. photos. Aspect Ratio is particularly important when printing photos. If you try printing to a size that doesn't conform to the film's aspect ratio, then your photo will either get cropped or will have white space around the edges. Point and shoot cameras and computer monitors usually have an aspect ratio of 4:3.

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... The Rule of Thirds?

A simple way to improve the composition of your photos is to follow The Rule of Thirds. Divide your view into thirds, both horizontally and vertically. Imagine drawing horizontal and vertical lines so that you have 9 evenly sized rectangles. The 4 intersection points are your optimal points for placing your subject. More and more point and shoot cameras now offer a feature where you can turn on gridlines on your display screen. This helps to quickly compose your shots.

The Rule of Thirds helps you to compose well balanced shots that will make your photos more interesting and more pleasing to the eye. This same technique is often used by artists. Even though it's called the Rule of Thirds, keep in mind that it is more of a "guideline" than a fixed "rule". Depending on your photo, sometimes the Rule of Thirds should be ignored. Each photo is unique and should be composed in a way that suits the photo.