Get the correct exposure by understanding camera metering modes…

October 15, 2010

Every modern DSLR has something called “Metering Mode”, also known as “Camera Metering”, “Exposure Metering” or simply “Metering”. Knowing how metering works and what each of the metering modes does is important in photography, because it helps photographers control their exposure with minimum effort and take better pictures in unusual lighting situations. In this “understanding metering modes” article, I will explain what metering is, how it works and how you can use it for your digital photography.

Metering is how your camera determines what the correct shutter speed and aperture should be, depending on the amount of light that goes into the camera and the sensitivity of the sensor. Back in the old days of photography, cameras were not equipped with a light “meter”, which is a sensor that measures the amount and intensity of light. Photographers had to use hand-held light meters to determine the optimal exposure. Obviously, because the work was shot on film, they could not preview or see the results immediately, which is why they religiously relied on those light meters.

Today, every DSLR has an integrated light meter that automatically measures the reflected light and determines the optimal exposure. The most common metering modes in digital cameras today are:

Matrix Metering (Nikon), also known as Evaluative Metering (Canon)
Center-weighted Metering
Spot Metering (Nikon), also known as Partial Metering (Canon)

You can see the camera meter in action when you shoot in Manual Mode – look inside the viewfinder and you will see bars going left or right, with a zero in the middle, as illustrated below.

Metering shown in Nikon Viewfinder

If you point your camera at a very bright area, the bars will go to “+” side, indicating that there is too much light for the current exposure settings. If you point your camera at a very dark area, the bars will go to the “-” side, indicating that there is not enough light. You would then need to increase or decrease your shutter speed to get to “0″, which is the optimal exposure, according to your camera meter.

A camera meter is not only useful for just the Manual Mode – when you choose another mode such asAperture Priority, Shutter Priority or Program Mode, the camera automatically adjusts the settings based on what it reads from the meter.

Camera meters work great when the scene is lit evenly. However, it gets problematic and challenging for light meters to determine the exposure, when there are objects with different light levels and intensities. For example, if you are taking a picture of the blue sky with no clouds or sun in the frame, the image will be correctly exposed, because there is just one light level to deal with. The job gets a little harder if you add a few clouds into the image – the meter now needs to evaluate the brightness of the clouds versus the brightness of the sky and try to determine the optimal exposure. As a result, the camera meter might brighten up the sky a little bit in order to properly expose the white clouds – otherwise, the clouds would look too white or “overexposed”.

What would happen if you added a big mountain into the scene? Now the camera meter would see that there is a large object that is much darker (relative to the clouds and the sky), and it would try to come up with something in the middle, so that the mountain is properly exposed as well. By default, the camera meter looks at the light levels in the entire frame and tries to come up with an exposure that balances the bright and the dark areas of the image.

MATRIX METERING

Matrix Metering or Evaluative Metering mode is the default metering mode on most DSLRs. It works similarly to the above example by dividing the entire frame into multiple “zones”, which are then all analyzed on individual basis for light and dark tones. One of the key factors (in addition to color, distance, subjects, highlights, etc) that affects matrix metering, is where the camera focus point is set to. After reading information from all individual zones, the metering system looks at where you focused within the frame and marks it more important than all other zones. There are many other variables used in the equation, which differ from manufacturer to manufacturer. Nikon, for example, also compares image data to a database of thousands of pictures for exposure calculation.

You should use this mode for most of your photography, since it will generally do a pretty good job in determining the correct exposure. I leave my camera metering mode on matrix metering for most of my photography needs, including landscape and portrait photography.

CENTER WEIGHTED METERING

Using the whole frame for determining the correct exposure is not always desirable. What if you are trying to take a headshot of a person with the sun behind? This is where center-weighted metering comes in handy. Center-weighted Metering evaluates the light in the middle of the frame and its surroundings and ignores the corners. Compared to Matrix Metering, Center-weighted Metering does not look at the focus point you select and only evaluates the middle area of the image.

Use this mode when you want the camera to prioritize the middle of the frame, which works great for close-up portraits and relatively large subjects that are in the middle of the frame. For example, if you were taking a headshot of a person with the sun behind him/her, then this mode would expose the face of the person correctly, even though everything else would probably get heavily overexposed.

SPOT METERING

Spot Metering only evaluates the light around your focus point and ignores everything else. It evaluates a single zone/cell and calculates exposure based on that single area, nothing else. This is a good mode to use for bird photography, because the birds mostly occupy a small area of the frame and I need to make sure that I expose them properly, whether the background is bright or dark. Because the light is evaluated where I place my focus point, I could get an accurate exposure on the bird even when the bird is in the corner of the frame. Also, if you were taking a picture of a person with the sun behind but they occupied a small part of the frame, it is best to use the spot metering mode instead. When your subjects do not take much of the space, using Matrix or Center-weighted metering modes would most likely result in a silhouette, if the subject was back-lit. Spot metering works great for back-lit subjects like that.

Another good example of using spot metering is when photographing the Moon. Because the moon would take up a small portion of the frame and the sky is completely dark around it, it is best to use Spot metering – that way, we are only looking at the light level coming from the moon and nothing else.

Some DSLRs like the Canon 1D/1Ds are capable of multi-spot metering, which basically allows choosing multiple spots to measure light and come up with an average value for a good exposure.

Working the Lines in Photography

October 10, 2010

Lines can be effective elements of composition, because they give structure to your photographs. Lines can unify composition by directing the viewer’s eyes and attention to the main point of the picture or lead the eyes from one part of the picture to another. They can lead the eyes to infinity, divide the picture, and create patterns. Through linear perspective, lines can lend a sense of depth to a photograph. (Linear perspective causes receding parallel lines to appear to converge in the picture. This allows you to create an illusion of depth in your pictures.)

The viewer’s eyes tend to follow lines into the picture (or out of the picture) regardless of whether they are simple linear elements such as fences, roads, and a row of phone poles, or more complex line elements, such as curves, shapes, tones, and colors. Lines that lead the eye or direct attention are referred to as leading lines. A good leading line is one that starts near the bottom corner of the scene and continues unbroken until it reaches the point of interest. It should end at this point; otherwise, attention is carried beyond the primary subject of the photograph. The apparent direction of lines can often be changed by simply changing viewpoint or camera angle.

Vertical, diagonal, horizontal, and curved lines create different moods. Vertical lines communicate a sense of strength, rigidity, power, and solidarity to the viewer. On the other hand, horizontal lines represent peace, tranquillity, and quietness. A generally accepted practice is to use a vertical format for pictures having predominantly vertical lines and horizontal format for pictures having predominantly horizontal lines. Again, this is a generally accepted practice, NOT a rule.

Emphasis: Focal Points in Design

October 9, 2010

Something that is singled out or made more prominent has emphasis. An element of a design that dominates or becomes the center of interest has emphasis. Within the visual components of a page design, emphasis is applied to individual parts such as a word or phrase by changing its appearance, making it stand out. Sometimes considered a principle of design on its own, emphasis can be created using all of the various elements and principles of design.

Emphasis and the Elements of Design
Create a focal point by making one element of the design more prominent or eye-catching than the others.

Line. In a design composed of horizontal lines, the vertical line becomes the focal point.
Shape. A square stands out from a group of circles or organic shapes.
Mass. The physically or visually heavier element or piece commands more attention.
Texture. Embossing adds tactile interest and emphasis.
Color. A splash of color or a strong change in value in an otherwise gray piece will draw the eye.

Emphasis and the Principles of Design
Use the arrangement of the page components to create a focal point or visual hierarchy of dominant and subordinant elements.

Balance. A perfectly symetrical piece may have no focal point because each element is equally emphasized. Radial balance generally draws the eye first to the central point in the design.
Proximity. A part of the design that is isolated from other parts can become a focal point.
Alignment. The eye is naturally drawn to a point in or near the center of a page, giving elements in that area perceived importance.
Repetition. Repeating an image or a word can establish its importance.
Contrast. Set words or phrases in a contrasting bold type or italics to give them emphasis.
White space. Use white space to isolate elements and give them emphasis.

Why are certain colors used in Advertising and Design?

October 5, 2010

YELLOW

Use yellow to evoke pleasant, cheerful feelings. You can choose yellow to promote children’s products and items related to leisure. Yellow is very effective for attracting attention, so use it to highlight the most important elements of your design. Men usually perceive yellow as a very lighthearted, ‘childish’ color, so it is not recommended to use yellow when selling prestigious, expensive products to men – nobody will buy a yellow business suit or a yellow Mercedes. Yellow is an unstable and spontaneous color, so avoid using yellow if you want to suggest stability and safety. Light yellow tends to disappear into white, so it usually needs a dark color to highlight it. Shades of yellow are visually unappealing because they loose cheerfulness and become dingy.

RED

Red brings text and images to the foreground. Use it as an accent color to stimulate people to make quick decisions; it is a perfect color for ‘Buy Now’ or ‘Click Here’ buttons on Internet banners and websites. In advertising, red is often used to evoke erotic feelings (red lips, red nails, red-light districts, ‘Lady in Red’, etc). Red is widely used to indicate danger (high voltage signs, traffic lights). This color is also commonly associated with energy, so you can use it when promoting energy drinks, games, cars, items related to sports and high physical activity.

GREEN

Green is the color of nature. It symbolizes growth, harmony, freshness, and fertility. Green has strong emotional correspondence with safety. Dark green is also commonly associated with money.

Green has great healing power. It is the most restful color for the human eye; it can improve vision. Green suggests stability and endurance. Sometimes green denotes lack of experience; for example, a ‘greenhorn’ is a novice. In heraldry, green indicates growth and hope. Green, as opposed to red, means safety; it is the color of free passage in road traffic.

Use green to indicate safety when advertising drugs and medical products. Green is directly related to nature, so you can use it to promote ‘green’ products. Dull, darker green is commonly associated with money, the financial world, banking, and Wall Street.

BLUE

Blue is considered beneficial to the mind and body. It slows human metabolism and produces a calming effect. Blue is strongly associated with tranquility and calmness. In heraldry, blue is used to symbolize piety and sincerity.

You can use blue to promote products and services related to cleanliness (water purification filters, cleaning liquids, vodka), air and sky (airlines, airports, air conditioners), water and sea (sea voyages, mineral water). As opposed to emotionally warm colors like red, orange, and yellow; blue is linked to consciousness and intellect. Use blue to suggest precision when promoting high-tech products.

Blue is a masculine color; according to studies, it is highly accepted among males. Dark blue is associated with depth, expertise, and stability; it is a preferred color for corporate America.

Avoid using blue when promoting food and cooking, because blue suppresses appetite. When used together with warm colors like yellow or red, blue can create high-impact, vibrant designs; for example, blue-yellow-red is a perfect color scheme for a superhero.

PURPLE

Purple combines the stability of blue and the energy of red. Purple is associated with royalty. It symbolizes power, nobility, luxury, and ambition. It conveys wealth and extravagance. Purple is associated with wisdom, dignity, independence, creativity, mystery, and magic.

According to surveys, almost 75 percent of pre-adolescent children prefer purple to all other colors. Purple is a very rare color in nature; some people consider it to be artificial.

Light purple is a good choice for a feminine design. You can use bright purple when promoting children’s products.

WHITE

White is associated with light, goodness, innocence, purity, and virginity. It is considered to be the color of perfection.

White means safety, purity, and cleanliness. As opposed to black, white usually has a positive connotation. White can represent a successful beginning. In heraldry, white depicts faith and purity.

In advertising, white is associated with coolness and cleanliness because it’s the color of snow. You can use white to suggest simplicity in high-tech products. White is an appropriate color for charitable organizations; angels are usually imagined wearing white clothes. White is associated with hospitals, doctors, and sterility, so you can use white to suggest safety when promoting medical products. White is often associated with low weight, low-fat food, and dairy products.

BLACK

Black is associated with power, elegance, formality, death, evil, and mystery.

Black is a mysterious color associated with fear and the unknown (black holes). It usually has a negative connotation (blacklist, black humor, ‘black death’). Black denotes strength and authority; it is considered to be a very formal, elegant, and prestigious color (black tie, black Mercedes). In heraldry, black is the symbol of grief.

Black gives the feeling of perspective and depth, but a black background diminishes readability. A black suit or dress can make you look thinner. When designing for a gallery of art or photography, you can use a black or gray background to make the other colors stand out. Black contrasts well with bright colors. Combined with red or orange – other very powerful colors – black gives a very aggressive color scheme.

Photography Tip for Black and White Landscapes

October 3, 2010

When shooting black and white landscapes look for ‘active skies’. The skies with breathtaking and wonderful cloud formations will almost always translate to great black and white photography. Having skies with so much ‘action’ in them add mood and a really dynamic look and feel to images. Without this active element images will look rather empty and dull. I think the same principle could be applied to most types of black and white images that have large parts of them dominated by any one thing. If a large part of your image is all the same tone the image can look quite lifeless (unless of course you’re going for a more minimalist look). (photograph Golden-Gate-Before-the-Bridge by Ansel Adams)

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