What is... White Balance?

White Balance is the intensity of red, green and blue coming from a light source. On SLR cameras, white balance helps to create correct color balance by compensating for light that is different than daylight.

Correcting Exposure in Photoshop

There are two basic tools in Photoshop for correcting exposure:

Levels dialog - used for maximizing tonal range and rough brightness adjustments.
Curves dialog - fine tuning the tonal balance and contrast.

When viewing the histogram of an image, if the left side (shadow) ends abruptly this means that the image was "clipped" and that the darkest areas of the image will be rendered as solid black. This happens when the darkest areas of an image are below the image sensors detection range.

The Levels dialog is a quick and easy way to adjust the exposure of your image. Open the Levels dialog by selecting Image...Adjustments from the menu. From here you can either do Auto Levels or Manual Levels. The Auto Levels command will automatically stretch the histogram so that there is a better distribution from shadows on the left to highlights on the right. If you prefer to have more control over the results, you can use Manual Levels. With Manual Levels, you adjust the sliders under the histogram until you get your desired results. Typically, when adjusting an underexposed image you will adjust the middle and right sliders.

Basic Lens Components

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.

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.

Canon EOS Cameras: Post-Process Sharpening

Canon EOS digital cameras use an anti-aliasing filter that improves color rendition. This filter causes a softening effect that slightly reduces the sharpness of the image. To improve the sharpness of the image, you should apply an Unsharp Mask Filter in Adobe Photoshop.

Here are the recommended settings for the Unsharp Mask Filter:
Amount: 300%
Radius: 0.3 pixels
Threshold: 0 pixels

Portraits - To Flash Or Not To Flash?

When taking portraits, natural lighting is far superior to using your camera's flash. Your onboard flash can cause red-eye and overexposed faces. Instead, take your portraits outside or if you need to take them inside, take them in the brightest room with the curtains and blinds open. As always, early A.M. and early P.M. hours are the best time.