digital photography

How to Use Focal Lock for Precise Focus

Use focal lock to ensure the right parts of your photo are in focus.

Your camera’s autofocus tool will typically focus on the center of your frame — so it’s not the most reliable tool when your subject is off-center. Focal locking allows you to select the exact spot you want in focus.

Here’s how to do it: 

  1. Pose your subject and compose your shot.

  2. Aim your camera's focal point (it will light up red in your viewfinder) at the exact spot you want to focus on. Press the shutter button down halfway.

  3. Without releasing the shutter, move your camera back to recompose the shot. Then press the button down fully to take your shot.

In your final image, the initial spot where you pressed the shutter halfway will be in focus, even though you moved the camera afterwards.

In addition to being used for off-center subjects, focal locking can be used in standard portraits for sharply focused eyes: frame your subject, pull your camera up to lock the focus on the eyes, then pull the camera back down to position your subject in the center of the frame.

Understanding Shutter Speed

Shutter speed is the length of time that the shutter is open, or the amount of time that the camera’s sensor views your scene. A fast shutter speed freezes action, while a slow shutter speed will create a “motion blur.”  A slow shutter speed may be used to convey a sense of movement — to show water flow, for example, or if you’re photographing a runner, you can use a slow shutter setting to convey a sense of speed.

Shutter speed is measured in seconds, or fractions of a second: 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, etc. (the speed typically doubles with each camera setting).

So how do you decide which shutter speed to use? Ask yourself what’s moving in the scene, and how you’d like to capture it — whether you want your image to have a sense of movement, or if you’d like to freeze movement. Movement typically freezes at 1/500th of a second or faster.

If you use a shutter speed slower than 1/60th of a second, you’ll likely need a tripod. It will be difficult to avoid holding your camera steady for this long, and you may get an unintentional blur in your image.

Remember that shutter speed affects exposure, so if you’re working in manual mode and change the shutter speed, you’ll also have to adjust the ISO and aperture to maintain exposure.

You may also choose to work in Shutter Priority Mode, usually indicated by a “Tv” or “S” symbol on your camera. In this semi-manual mode, you select the shutter speed and the camera will automatically select the proper aperture. A fast shutter speed will use a small depth of field (large aperture).

Understanding Aperture

When you press your camera’s shutter release button, a hole opens up to let the image sensor view the scene. This opening is the aperture, which you can adjust to let more or less light hit your camera’s sensor.

Aperture is measured in “f-stops”: f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22.
Note: the large apertures (larger openings) are given smaller numbers.

The size of the lens opening is doubled, or halved, when you move from one f-stop to the next. The smaller the f-stop number, the larger the opening.

When you change your camera’s aperture, the main thing that will change is the depth of field (DOF), which controls how much of your shot is in focus. With a large depth of field, most of your image will be in focus (a large DOF is typically used for landscape shots). When you use a small depth of field, part of the image will in focus and the rest will be blurry. A shallow depth of field is often used for portraits (it keeps the focus on the subject, rather than the background), macro photography, and creative shots. Smaller f-stop numbers (large apertures) decrease the depth of field, while large f-stop numbers (small apertures) increase the amount of the scene that’s in focus.

If you’re working in your camera’s manual mode, keep in mind that when you change the aperture, you’ll also have to adjust the ISO and shutter speed to maintain exposure. (More on that here.) 

You can also work in Aperture Priority Mode — usually indicated by “A” or “Av” on your camera. In this semi-manual mode, you select the f-stop number and the camera will automatically select the proper shutter speed.

Understanding White Balance

To get the colors in your photos as accurate as possible, it’s helpful to understand your camera’s “white balance.” When properly adjusted, this setting will help your photos look natural.

What You Should Know

Different light sources and lighting conditions produce different colors, or “temperatures,” which is measured in units of Kelvin (K). Fluorescent lighting, for example, adds a bluish tint to photos, while tungsten (bulbs and incandescent lights) can create a yellow cast.

Our eyes naturally adjust to different color temperatures, so you won’t notice any color cast before taking a picture. Our cameras, however, do not: they need us to tell them how to treat different type of light. This is where “white balance” comes in — it balances the color temperature in your images. For cool light (green or blue), you’ll tell the camera to warm things up and for warm light, you’ll tell it to cool down. 

If properly balanced, white objects will not have a blue or yellow tint in your photos.

How to Adjust Your White Balance

Semiautomatic Settings

Most digital cameras have preset white balances. This often produces decent results, although it’s not as accurate as a manual adjustment (see below). The settings most commonly offered are: 

  • Auto: the camera makes its best guess for each individual photo; can be set anywhere from 2,000-10,000 K
  • Daylight: for shooting in direct sunlight; 5,000-5,500 K
  • Shade: for when you're shooting in the shade (no direct sun) with a blue sky; 7,000-7,500 K
  • Cloudy: white sky; 6,000-6,500 K
  • Tungsten: for shooting indoors with incandescent lighting (standard household light bulb); 2,800-3,200 K
  • Fluorescent: typically found in commercial spaces; 3,400-3,800 K
  • Flash: emulates daylight; 5,000-5,500 K

Manual Settings

Most DSLRs allow for manual white balance adjustments. Basically, you tell your camera what white looks like (by holding up a piece of white paper, for example), so it has a point of reference for how other colors should look. This setting can be found in different spots for various camera models — some have a “WB” button on the camera body, while others are found in the “settings” section. (If you’re not sure where to find it, refer to your camera’s manual or Google the camera model.)

Some cameras also have the option to manually set the color temperature in degrees Kelvin.

Understanding Exposure

If you want to venture out of your camera’s auto mode to have more control over your images, one of the most important things to understand is exposure, which determines how light or dark your photo will be.

If your camera doesn’t let in enough light, your photo will underexposed and you won’t see things very well. If you let in too much light, your photo will be overexposed – it’ll be too bright to see details. Your goal is to achieve perfect exposure by balancing three main elements: ISO, aperture, and shutter speed.

  • ISO is the measure of the camera sensor’s light sensitivity.
  • Aperture is the opening in a lens that can be adjusted to let more or less light hit a digital camera’s sensor.
  • Shutter speed is the amount of time, expressed in fractions of a second, that the shutter is open to let light through the aperture.

ISO, aperture, and shutter speed all work together. These settings can help you achieve certain creative effects, but you have to keep in mind that if you adjust one setting, the other two will be affected. You’ll have to adjust all three in order to maintain perfect exposure. Refer to the chart below to see how they affect your photos.

 
Exposure cheat sheet. Aperture, shutter speed, and ISO settings for digital photography.
 

Your DSLR should have a light meter to gage your exposure. If your meter is at 0, your photo is perfectly exposed; -2 is underexposed, and +2 is overexposed.

If your pictures are too bright, try upping your shutter speed, increasing your aperture, and/or reducing your ISO. If your pictures are too dark, reduce the shutter speed, decrease your aperture, and/or increase the ISO.