PhotographyTips.com - the #1 guide to better conventional and digital photography Become a Member iPhone Posing GuideGuide to Posing the Female Model BookGuide to Posing the Model CD
Search
Login

Member Login

Find us on Facebook
Follow us on Twitter
Find us on Flickr
Connect with us on LinkedIn

SPONSORS

Sell Photos Online

FEATURED SITES


Focusing

What you need to know about focusing your pictures.


A camera's focus screen can be plain or may contain multiple focusing areas. There are several variations between the two extremes.
A camera's focus screen can be plain or may contain multiple focusing areas. There are several variations between the two extremes.

AUTOFOCUS

Just about every digital camera available today (and many film cameras) are equipped with automatic focusing capability, more commonly known as autofocus, or just AF.

Autofocus is typically activated by applying light pressure on the shutter button - not enough to trip the shutter to take a picture, but just enough to get autofocus working, generally about halfway. Looking through the viewfinder you will see whatever your camera is aimed at automatically come into sharp focus, unless it is too close for your camera's focusing ability.

Sometimes what you want your autofocus camera to focus on will not come into sharp focus. Your subject may be off to the side, while your camera is focusing on the background in the center of the viewframe. You can see how this can occur by looking in the viewfinder at the focusing area marked on the viewfinder screen. If your subject is not within this area, the camera won't focus on it. (We explain what you can do about it further below.)

Most popular, inexpensive cameras have one focusing area in the center of the viewfinder screen, often indicated by lines etched on the focusing screen or by a rectangle or circular shape. Some screens may be absolutely plain with no indication of a focusing area.

More expensive cameras, especially high-quality SLRs and dSLRS, will have a number of focusing areas - typically one in the center and others spaced around it - giving you a choice of which part of the scene to place in focus. The photographer chooses which of the focusing areas to use by pressing the Focus area selector, a toggle switch or dial on the camera that highlights the active focusing area in some manner. This focusing mode is known by several names, including Focus area selection, Zone autofocus, Flex autofocusing and Area autofocusing. As you become used to your camera, you will find yourself automatically selecting the right focusing area for your subject's placement in the scene.


How do you achieve proper focus of a subject that is off center when using a camera that has a single, centered focusing area?

It's pretty simple, really.

  • Aim your camera at the subject so the subject's in the center of the frame (as illustrated by the middle image on the right).
  • Lightly depress the shutter button to place your subject in focus. (In some cameras, an in-focus indicator will appear in the viewfinder.)
  • The key is to keep the shutter button lightly depressed while you move the camera to re-frame the scene as you wish it to appear in the image.
  • Keeping the shutter button depressed keeps your subject in focus - in effect, locking the camera's focus on the subject.
  • Now re-frame the scene so your subject is placed off to the side, where you want it to appear in the picture.
  • Fully depressing the shutter button will take the picture with the subject in proper focus.
Watch that you don't step closer or otherwise change the distance between the lens and the subject. If you do, you will need to start over to be sure the subject is in focus at the new distance.

What if you wish to take more than one photo at the same focus setting?

Focus usually remains locked between shots provided you keep the shutter release button at least halfway depressed, permitting you to take several pictures in succession at the same focus setting.

Note that not all cameras have focus lock ability, but the majority does. Some dSLRs and SLRs even have a separate AF-Lock button that permits you to remove your finger from the shutter release button and still keep the subject in focus. When you use the camera's AF-Lock, you're also locking in the auto-exposure (AE) settings, ensuring that the subject will be sharply focused and properly exposed. For this reason, the button is sometimes referred to as the AF/AE-Lock button.

Autofocus does not usually perform well when:

  • the subject appears very small in the focusing area (e.g. a flying insect, or a small bird at a distance);
  • there is little or no contrast between the subject and its background, such as you might find in a foggy or dark scene;
  • different objects at varying distances from the lens appear in the focusing area (for example, tree branches between you and your subject);
  • your subject has a regular geometric pattern, as you might find in a building's row of windows;
  • the focusing area contains significantly contrasting areas of brightness, as you'd find with a subject partially in deep shade and partially in bright sunlight, or a scene that contains bright, shiny material; and
  • the scene contains many fine details, like a field of wildflowers.

AF ASSIST

For low light situations, your camera may have a built-in Autofocus Assist beam that enables autofocusing when aimed at your subject, which must usually be around ten feet away or closer. AF Assist will cause a camera's automatic flash to fire. With some cameras, when the subject is very dark and autofocus is having trouble working properly, attaching a dedicated flash unit that has an AF-assist illuminator will help autofocusing. You could also move a room lamp or other source of illumination close to your subject to lock in focusing, then move it away or turn it off in order to take the picture.

If your camera focuses only on the center of the viewframe, an off-center subject may be out of focus. Place the subject in the center of the frame, use focus lock, then reframe to take the picture.
If your camera focuses only on the center of the viewframe, an off-center subject may be out of focus. Place the subject in the center of the frame, use focus lock, then reframe to take the picture.

Cameras that have continuous focusing capability can track a moving subject and keep it in focus. even when it moves away from or closer to the camera.
Cameras that have continuous focusing capability can track a moving subject and keep it in focus. even when it moves away from or closer to the camera.

PREDICTING WHERE YOUR MOVING SUBJECT WILL BE

If you are taking pictures of a moving subject that is difficult to get into sharp focus, try focusing on an area into which you know the subject is heading, then quickly take its picture as it enters the prefocused area. On a race track, for example, you might focus on a curved area of the track where the participants will be facing you. Take their picture when they reach that area. (This technique works well with either auto focusing or manual focusing, and some high end cameras have a focusing mode called Predictive focus tracking that assists you with this technique - see below.)

FOCUSING MODES

Depending on your model of camera, it may have one or more focusing modes. High end dSLRs and SLRs are more likely to have a greater selection, providing the photographer with more versatility than low end cameras. Here is a list of focusing modes you may encounter and information on their use:

  • Focus tracking - Some dSLRs and SLRs are capable of sophisticated focus tracking of a moving subject, using a feature known as continuous focusing, focus tracking or sometimes constant auto focus. When the subject that is in focus moves, even away from or towards the lens, continuous focusing will track the subject and keep it in focus as it moves. Some SLRs and dSLRS will even track a subject that moves behind an object, like a bird flying behind a pole, and predict where the subject will be when it comes back into view, keeping it in focus.
    In some cameras in single-servo autofocus, the subject must come to a stop in order for focus to be locked, but in continuous-servo AF, focus does not lock when the subject stops moving. It continues to track the subject, permitting you to take a series of pictures. A small disadvantage of this focusing mode that you should be aware of but not worry too much about is that your camera's battery will drain a little faster than normal, since the lens is constantly focusing on the subject, and requires power to do so.
  • Predictive focus tracking - This mode causes your camera to automatically take a picture when a moving subject reaches a selected spot in the scene you are photographing.
  • Focus area selection - See the description in the fifth paragraph of this article, above. Note that some cameras have a Focus selector lock that prevents the selected focus area from changing when the multi-selector dial is pressed.
  • Closest-subject priority - A variation of Focus area selection, this option causes the subject that is closest to the camera to always be in focus, no matter where it is in the frame.
  • Group dynamic-AF - Similar to Closest-subject priority, this mode automatically focuses the lens on the closest subject in a selected area of the frame.
  • Spot focusing - Permits the photographer to select a very tiny area in the scene as the point where autofocusing is to occur. A photographer may, for example, wish to be absolutely sure that a model's eye or another important, small element is in sharp focus. This mode ensures that it will be in sharp focus.
  • Manual focusing - Shuts off autofocus, and requires the photographer to manually focus the lens.

Be sure to change your focusing mode back to its normal autofocus setting after using an optional focusing mode. Some cameras may not automatically reset to the default normal mode, even after the camera has been turned off.


MANUAL FOCUSING

Most older traditional film cameras either had a fixed focus lens (one that couldn't be focused since its focusing was set and your subjects needed to be within the lens' depth of field to be sharp) or were manually focused. Autofocusing had yet to be introduced. Nowadays, there are still some inexpensive digital cameras that have a fixed focus lens, and quite a few autofocus cameras offer the ability to switch to manual focusing if you wish. Most high-end SLRs and dSLRs are also capable of both autofocusing and manual focusing.

When would you use manual focusing (MF) even if your camera is also capable of auto focusing?

There are several occasions when focusing manually will produce the results you seek.

  • You may have attached a lens to your SLR or dSLR that does not support auto focusing (a non-AF lens).
  • The circumstances of the scene you are photographing may make auto focusing unreliable.
  • You may be shooting a photograph (a macro photograph, for example) where extremely shallow depth of field is called for, and you want to ensure that the areas in focus are exactly correct.
  • A particularly long lens may be slow to focus automatically, and you may find you can manually focus it more quickly on a rapidly-moving subject.
  • The scene you are photographing may have objects moving between the lens and the subject, such as foliage being moved by the wind or people walking back and forth in front of you.
  • You may have attached a filter to the lens that makes auto focusing difficult or impossible.
  • You want to intentionally blur an image.
  • You wish to focus using the distance scale on the lens (if your lens has one).
  • You may wish to focus between two objects in a scene (one closer to you than the other) to bring a specific area into the lens' depth of field. (See Hyperfocal distance)
  • You may be photographing a scene in a completely dark area into which you will be adding light only when the lens is open. One example of this would be painting with light, where you would first set the focus manually with the lights on, then switch off the lights in order to begin "painting" your subject.
  • Some photographers, wanting to control all aspects of their photography, actually prefer to manually focus the majority of their photographs.

Each camera may have a different means of selecting manual focus. You may need to use the camera's menu with one camera, and with another, you may be able to select manual focusing by pressing a button. Some autofocus lenses may also need to be set to manual focus using a switch or selector on the collar, and must be switched back to autofocus in order for autofocusing to function. Some even permit you to over-ride autofocusing just by manually turning the collar of the lens.

Selecting manual focus can usually be done by a switch on a camera and sometimes also on a lens, if your equipment is capable of manual focusing.
Selecting manual focus can usually be done by a switch on a camera and sometimes also on a lens, if your equipment is capable of manual focusing.

Shallow depth of field is a characteristic of close-up focusing (top picture). Parallax error occurs when the
Shallow depth of field is a characteristic of close-up focusing (top picture). Parallax error occurs when the "view" seen by the lens is different than the view through the viewfinder.

FOCUSING WHEN SHOOTING CLOSE-UPS

Close-up photography can present the photographer with focusing problems. All lenses have a minimum focusing distance. Any object closer to the lens than the minimum distance will be out of focus. Although you can't switch lenses on many popular digital cameras, many manufacturers make wide-angle and telephoto adapters and accessory close-up lenses that screw onto the front of the camera's lens. Fixing a close-up lens to the camera's lens will shorten the minimum distance in the same manner as someone using a magnifying glass.

If your camera has a macro (macrophotography) mode, you can switch to it for extremely close subjects. Pressing the shutter button halfway down should bring the subject or some of it into sharp focus. We say "some of it" because depth of field is very shallow when shooting macrophotography, and may only bring part of your subject into focus.

PARALLAX

You may not be able to see the close-up subject you are photographing through the camera's optical viewfinder due to parallax error and may need to switch to the camera's electronic viewfinder to see it.

Parallax error occurs when the lens you look through is not the lens that takes the picture, and the slightly-separated perspectives make close-up pictures tricky to frame without cutting off a portion of the subject. Some digital cameras automatically turn on the electronic viewfinder when they are switched to macro mode, allowing you to see the view that will be captured through the image-taking lens. And of course other cameras may only have an LCD viewfinder, avoiding the problem of parallax error. Parallax error is also not a problem with a dSLR or an SLR, which shows you the same view that the lens "sees" through the optical viewfinder.


YOU CAN CONTROL HOW MUCH OF A SCENE WILL BE IN FOCUS

What is and isn't in focus is greatly affected by the aperture of the lens. The range of objects at varying distances from the camera that are acceptably sharp is known as the depth of field, which is determined by the size of the aperture.

We recommend that you learn all about depth of field and its prime importance to understanding how you can control what will and won't be in focus in your pictures.


Further information...

Painting with light

Macrophotography
Related topics...

Depth of Field

Close-up lens

Hyperfocal distance

How much will be in focus?