According to LG, it only takes 0. It works in low-light conditions. Instead, it emits its own beam of light from which the distance to the object can then be determined. According to LG, laser auto-focus works best when the object is within 0.
The total range of effectiveness is around 5m beyond this, the phone will fall back to contrast-detection. It can sometimes be confused by reflections. For instance, if you try to take photos through a window, the laser beam could be reflected by the window.
This will give an incorrect measurement of distance the image will be focussed on the window rather than the object. Laser auto-focus is currently available only on high-end smartphones from LG. This will allow you to capture the full amount of detail. At present, most smartphones use a technique called contrast-detection to focus their images. In the past year, a number of alternative techniques have appeared on high-end smartphones for better auto-focus. Apple and Samsung are using phase-detection auto-focus whereas LG is using laser auto-focus.
Both methods are much faster than contrast-detection though they also both have their own downsides. For the best smartphones with a day money back guarantee, check out the giffgaff store. Written by abdulf. Blog home. How autofocus works When taking photos of an object, your camera phone will capture the light coming from it. Fixed focus lenses In this example, only the blue ray of light is actually focussed.
There are currently three different methods for performing auto-focus on a smartphone: Contrast-detection auto-focus. The following image illustrates how contrast detection auto-focus works: Contrast detection autofocus In contrast-detection auto-focus, your cameraphone will move the lens back and forth until it finds the point of maximum contrast. Like contrast-detection, phase-detection auto-focus also works on analysing the light that comes into the lens. In low-light conditions, it can sometimes be difficult to analyse the image.
Active systems function beyond the scope of the normal optical systems. So far only two applications of active systems have been used. One of them uses sonar and the other uses infrared beams of light. The impracticality of using these systems in camera systems notwithstanding, there are other drawbacks. For instance, active systems fail when you shoot through glass or underwater. Join over , photographers of all experience levels who receive our free photography tips and articles to stay current:.
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We would love to publish an article by you if you are interested in writing for us. That is what the microprocessor is looking for as it drives the lens back and forth. Passive autofocus must have light and image contrast in order to do its job. The image needs to have some detail in it that provides contrast. If you try to take a picture of a blank wall or a large object of uniform color, the camera cannot compare adjacent pixels so it cannot focus. There is no distance-to-subject limitation with passive autofocus like there is with the infrared beam of an active autofocus system.
Passive autofocus also works fine through a window, since the system "sees" the subject through the window just like you do.
Passive autofocus systems usually react to vertical detail. When you hold the camera in the horizontal position, the passive autofocus system will have a hard time with a boat on the horizon but no problem with a flagpole or any other vertical detail.
If you are holding the camera in the usual horizontal mode, focus on the vertical edge of the face. If you are holding the camera in the vertical mode, focus on a horizontal detail. Newer, more expensive camera designs have combinations of vertical and horizontal sensors to solve this problem. But it's still the camera user's job to keep the camera's sensors from being confused on objects of uniform color.
You can see how much area your camera's autofocus sensors cover by looking through the viewfinder at a small picture or a light switch on a blank wall. Move the camera from left to right and see at which point the autofocus system becomes confused. Here's a quick test to tell which autofocus system is in use in your camera some cameras may have both systems :. It is really up to the person using the camera to determine if the subject is in focus. The camera merely assists you in making this decision.
The two main causes of blurred pictures taken via autofocus cameras are:. Your eye has a fast autofocus! Try this simple experiment: Hold your hand up near your face and focus on it, and then quickly look at something past your hand in the distance. The distant item will be clear, and your hand will not be as clear. Look back at your hand. It will be clear, while out of the corner of your eye the same distant item will not be as clear.
Your camera is not nearly this quick or this precise, so you often have to help it. The camera user can often fool the autofocus system. A pose of two people centered in the picture may be unclear if the focus area the area between the two square brackets is in the middle of the two people.
The camera's autofocus system actually focuses on the landscape in the background, which is what it "sees" between the two people. The solution is to move your subjects off-center and use the focus-lock feature of your camera. Typically, focus lock works by depressing the shutter button part-way and holding it while you compose the picture.
The steps are:. You may also use the above procedure in the vertical direction, say when taking a picture with mountains or the shore in the background. Manual focus rings are still available on most SLR cameras. When taking a picture of an animal behind bars in a zoo, the autofocus camera might focus on the cage bars instead of the animal.
On most consumer-grade autofocus cameras, use manual focus when:. Autofocus in a video camera is a passive system that also uses the central portion of the image.
Though very convenient for fast shooting, autofocus has some problems:. You can sometimes "see" infrared via this simple experiment , using a camcorder with a TV monitor attached. Actual maximum tracking speeds also depend on how erratic the subject is moving, the subject contrast and lighting, the type of lens and the number of autofocus sensors being used to track the subject.
Also be warned that using focus tracking can dramatically reduce the battery life of your camera, so use only when necessary. Many cameras come equipped with an AF assist beam, which is a method of active autofocus that uses a visible or infrared beam to help the autofocus sensors detect the subject.
This can be very helpful in situations where your subject is not adequately lit or has insufficient contrast for autofocus, although the AF assist beam also comes with the disadvantage of much slower autofocus. Most compact cameras use a built-in infrared light source for the AF assist, whereas digital SLR cameras often use either a built-in or external camera flash to illuminate the subject.
When using a flash for the AF assist, the AF assist beam may have trouble achieving focus lock if the subject moves appreciably between flash firings.
Use of the AF assist beam is therefore only recommended for still subjects. Autofocus will almost always perform best with action photos when using the AI servo or continuous modes.
Focusing performance can be improved dramatically by ensuring that the lens does not have to search over a large range of focus distances. Perhaps the most universally supported way of achieving this is to pre-focus your camera at a distance near where you anticipate the moving subject to pass through. In the biker example to the right, one could pre-focus near the side of the road since one would expect the biker to pass by at near that distance.
Some SLR lenses also have a minimum focus distance switch; setting this to the greatest distance possible assuming the subject will never be closer can also improve performance. Be warned, however, that in continuous autofocus mode shots can still be taken even if the focus lock has not yet been achieved. Still photos are best taken using the one-shot autofocus mode, which ensures that a focus lock has been achieved before the exposure begins. The usual focus point requirements of contrast and strong lighting still apply, although one needs to ensure there is very little subject motion.
For portraits, the eye is the best focus point—both because this is a standard and because it has good contrast. Although the central autofocus sensor is usually most sensitive, the most accurate focusing is achieved using the off-center focus points for off-center subjects. If one were to instead use the central AF point to achieve a focus lock prior to recomposing for an off-center subject , the focus distance will always be behind the actual subject distance—and this error increases for closer subjects.
Accurate focus is especially important for portraits because these typically have a shallow depth of field.
Since the most common type of AF sensor is the vertical line sensor, it may also be worth considering whether your focus point contains primarily vertical or horizontal contrast.
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