Many of the latest DSLR cameras allow photographers to compose shots using the LCD monitor on the camera as …

 

Many of the latest DSLR cameras allow photographers to compose shots using the LCD monitor on the camera as well as the normal viewfinder. This Live View mode makes them as easy to use as a digicam and is one of the more attractive features novice photographers look for. However, live viewing has some significant benefits for experienced photographers as well.
It’s particularly valuable in situations where it is difficult to look through the viewfinder to compose shots, such as in crowd scenes where the camera must be held above your head or for taking close-ups of objects close to the ground and achieving precise compositions for macro and technical shots. It also comes in handy for portrait photographers because it allows them to engage with subjects without having the barrier of a camera between them.

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The Live View mode allows photographers to compose shots on the camera’s LCD screen, just as they can with a digicam. Grid overlays can be superimposed to assist shot composition.
The ability to see the subject exactly as the camera’s sensor ‘sees’ it is another benefit because it allows you to check focusing, exposure levels and colour balance in real-time and see the result you should obtain. Live View is great for checking image stabilisation.
It’s also an asset when you shoot with a remote control as well as for people who wear glasses. Live viewing is particularly useful for underwater photographers because it provides a view that is easy to see through a diving mask when the camera is in a waterproof housing.

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Live View mode is usually engaged via the camera’s menu system. Some Live View settings are controlled through the Custom Menu settings.
The main downside of live viewing is that it tends to be somewhat slower to use than viewfinder-based shooting. Because several components in the mirror mechanism must be moved to provide the live view, it usually takes longer to capture the shot. For this reason, Live View is best used for stationary subjects and really excels for studio photography.
Live viewing also involves higher power consumption. Because the sensor must remain active while the Live View mode is in use, the number of shots per charge decreases between 20% and 40%. Photographers must also keep a check on the camera’s working temperature as overheating can damage circuitry in high ambient temperatures. Most Live View systems shut down after a short time to prevent overheating.
Live View Types
The first Live View function introduced in a DSLR camera used a separate sensor to provide the live view display. This strategy is still in use in some DSLRs because it allows the lens to be focused without raising the main reflex mirror. Focusing is measurably faster with this type of Live View.
More recent applications of live viewing tend to favour using the camera’s image sensor to provide the live view for the LCD screen. This technique has the advantage of showing photographers the exact view the sensor will record; in other words 100% coverage of the subject.
When Live View mode is selected, half-pressing the shutter button flips the mirror up, blocking off the viewfinder. The image ‘seen’ by the camera’s sensor can be displayed on the LCD monitor. Most cameras allow you to simulate an exposure and/or zoom in to check the focus and fine detail in the shot. Many also allow you to enlarge the preview image to check focusing.
The other system blocks off the viewfinder and directs the light path to a secondary sensor, usually in the viewfinder housing, which provides the image for the LCD. This means there’s no need for the mirror to be raised to provide the live view. At the same time, the semi-reflecting main mirror passes light down to the AF sensor below the mirror chamber in the normal manner.
This allows the TTL phase-detection AF system to function normally in Live View mode, without requiring a separate contrast-detect AF system. The dual sensor design allows the camera’s AF system to be as responsive in Live View mode as it is when the viewfinder is used for shot composition, which means capture lag is reduced and faster continuous shooting speeds may be supported.
Some DSLRs include a Remote Live View function, which is enabled with special software and outputs the live view as video for viewing on computer monitor. This function improves remote shooting by making it possible to check such things as composition, focus, moirø©, and false colours quickly and easily on a monitor screen. It can work in tandem with remote capture systems supported by the camera.
A few cameras can capture a digital preview of the subject in Live View mode. This preview can be saved in JPEG format with the resolution you have selected in the camera’s menu.
Focusing in Live View Mode
Some cameras that support Live View shooting only support manual focusing, although a few of the more recently-released models allow autofocusing with Live View. Manual focusing is straightforward and involves turning the focusing ring on the lens until the subject looks sharp. Zooming in allows focus checking and you can select a particular AF point to zoom in on so as to be sure the critical areas in the shot are sharp.
Two autofocusing modes are commonly offered in cameras that use the main image sensor for live viewing and support autofocusing. The Quick mode is faster to use than the Live mode. However, the main mirror must be dropped to expose the AF sensor. This temporarily stops the live view and adds a brief delay to the image capture sequence. Most DSLRs in this category use contrast-based autofocusing systems to minimise this delay. However, a few revert to phase difference detection with certain lenses.

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Most DSLRs with Live View shooting capabilities include a magnification function for focus checking. There is no interruption to the live preview when magnification is applied.
The Live mode provides an uninterrupted view of the subject and is used for careful focusing plus exposure verification. Some cameras require you to hold down the AE/AF lock button to engage autofocusing in Live View mode. In a few cameras, this mode also supports ‘silent shooting’ in which an electronic first-curtain shutter scans silently across the sensor to record the image. It synchronises with the second shutter curtain to provide a slit exposure, thereby controlling light levels.
Cameras with dual-sensor Live View systems may provide a wider range of AF options than the single-sensor cameras. More detailed on-screen image overlays (see below), AF point selection and more advanced metering sensors may also be provided. However, the second sensor may not show exactly the same view of the subject as the main sensor captures so accurate shot composition may be more difficult to achieve.
If the camera has a depth-of-field preview button, it is usable in Live View mode in some cameras. This function stops the lens down to the shooting aperture and simulates the shooting exposure, enabling a check of metering accuracy in real time.
In some DSLRs, an electronic first-curtain shutter allows the camera to operate in Live View mode with the mechanical shutter completely open. The first curtain of the shutter synchronises with the mechanical second curtain, allowing exposures to be made with a moving slit shutter.
The resulting exposures are silent because the shutter-cocking noise and mirror bounce are eliminated. This system also reduces shutter release lag time and allows the camera to support faster continuous shooting speeds.
Image Overlays in Live View Mode
Pressing the Info or Display button allows you to change the information overlay on the image in Live View mode. Most cameras allow users to toggle between no data displays and varying levels of shooting data. Some will display AF points with or without the exposure metering circle.
Some cameras will also provide a grid line overlay and/or a histogram for checking exposure levels. Selected camera control settings may also be displayed as a semi-transparent overlay on the live view to allow photographers to adjust shooting parameters without leaving Live View.

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The live preview can be overlaid with a framing grid. The white rectangle in the centre represents the autofocussing sensor. (This can be moved in some cameras.)

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Some other menu settings – in this case the Picture Style menu – can be overlaid on the live preview image.
USEFUL URLs
There are several video clips that demonstrate Live View shooting on You Tube but very few other informative websites covering this topic.

 

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