HDSLR Guide Chapter 7: Monitoring
While LCDs on some cameras have a high resolution, at 3" most objects appear too small to accurately judge focus and frame a shot. It is also difficult to see the LCD in bright daylight. Most HDSLRs (except for cameras with an electronic viewfinder) disable the optical viewfinder during video/live mode, so it's of no use other than for setting up a shot before going into live mode. The optical viewfinder will also not show the entire frame of the image being recorded because the video does not use the full sensor's image.
Relying on the LCD screen will undoubtedly lead to mistakes that sometimes are caught only in post production when the footage is viewed on a larger monitor. It’s conceivable to get away with softer focus using wide-angle lenses if the intended viewing size of the final video will be small (such as a Web video), but it can get very distracting if the focus isn't accurate.
Focus issues aren't new for filmmakers, but HDSLRs in particular are at more risk for being out of focus because of their shallower depth of field. Aside from having the right elements in place for controlling focus (e.g. follow focus, manual lens), the image must be accurately viewed to ensure that what you see is what you get.
Although a 3" LCD is too small to judge focus from a handsbreadth away, the high-resolution LCDs on SLRs can make great viewfinders. Viewfinder adapters convert the LCD screen into a proper video viewfinder. Some options magnify the image several times, rendering better detail in the scene. If the camera operator is pulling his/her own focus, this can greatly improve accuracy.
Having the option to use the camera's LCD screen as a viewfinder is great for handheld or shoulder-mounted setups. Because most HDSLRs don't have a pivoting LCD screen, the viewfinder adapter is less usable when shooting from high or low angles.
Note: The lens on the viewfinder, like all optical elements, magnifies light and thus will also magnify the sun's rays; therefore, leaving the viewfinder on the camera in direct sunlight may cause damage to the LCD. The manufacturer will not be held liable for damage caused by improper use of its products.
Viewfinder: Features to Consider
The most basic function that all viewfinder adapters perform is isolating the LCD screen from surrounding light. For this reason, it's important that the point of contact between the viewfinder and the LCD screen is aligned correctly. If the adapter does not fit correctly, access to the surrounding buttons will be impeded, or the image will be cut off. The way the adapter is mounted to the camera can contribute to or impede the adapter's ability to seal out light.
The diopter changes the optical power of the lens inside the viewfinder. It is controlled by a ring on the viewfinder. For camera operators who don't have perfect vision, a diopter can make it more comfortable to view the image without eyeglasses. Not wearing glasses also allows the operator to use the eyecup more efficiently, sealing out external light as well as providing more stability. Not all adapters have a diopter, so keep an eye out for one if you need it.
A good eyecup will provide both comfort and additional stability to the camera (as another point of contact with the operator’s body). This means the eyecup should cover the eye socket comfortably. Some viewfinder adapters are designed to be viewed only from a distance instead of with the eye right up against the eyecup. This may be useful to some users, as it allows the full image to be viewed without blocking peripheral vision.
The length of the viewfinder needs to be compatible with the shoulder rig so that the camera is not positioned too far from or too close to the face, allowing a comfortable distance between the viewfinder and the eye. Certain shoulder supports are better matched with a longer viewfinder adapter.
In some situations, the lens in the LCD adapter may fog up and obstruct the view. Anti-fog spray can be applied to limit this, but many of the latest adapters include anti-fog properties on the optics, which is more convinient than spraying or wiping the optic before each use.
Adding an LCD adapter is a good option for traveling light and shooting small, but using an external monitor is the ideal way to examine video in many situations—before, during and after the shot. An external monitor provides the opportunity to see details not visible on a smaller screen, and allows much more precision when framing the shot.
The larger the screen that an image is viewed on, the easier it will be to set focus, exposure and framing of the shot. Of course, size isn't the only thing that matters; resolution is equally important for seeing fine details and edges that help to accurately judge focus.
A smaller (5-9") monitor mounted onto the camera rig can be used by the camera operator, while a larger (10-24") monitor may be used by the director or DP for verifying prior takes. When a dedicated focus puller (1st AC) pulls focus using a monitor, an additional monitor is usually required. It can either be mounted on the side of the camera (e.g. stabilizer and shoulder-mounted rigs) or the signal can be wirelessly transmitted to a monitor positioned with the 1st AC.
Monitors: Features to Consider
Although a larger monitor is better for viewing purposes, a camera-mounted monitor will usually be 9" or smaller. An important thing to consider about size is that the HDSLR signal will not fill the frame completely. Instead, it will be surrounded by information and black borders, which effectively shrinks the viewable image area. Some monitors have a feature to zoom in on the video image, which can help display the image closer to full screen size.
Larger monitors will typically offer higher resolutions for more clarity in the details. On the other hand, larger monitors are more expensive, add weight to the camera rig, and require heavier duty monitor-mounting arms.
The native resolution of a monitor determines how many pixels can be displayed from the incoming video signal. The ability to see each original pixel ensures that the image displays its full detail, which is very important for critical focus and also helps to spot moiré issues (lower resolutions soften the appearance of the moiré).
It's worth stressing that although some non-HD monitors are advertised as "HD," "1080p" and "720p," this may not mean the resolution of the monitor is HD. They may be able to accept incoming HD signals, but the image displayed may be scaled down to fit the monitor’s native resolution. In order for a monitor to display the "full" resolution of 1080p video, the native resolution must be 1920 x 1080. This resolution is not easy to find in small monitors. There are, however, a few monitors under 10" with close to full-HD resolution for under $1,500. These monitors make a difference in comparison to other lower-resolution monitors.
Aside from this, a good option is to have a larger monitor mounted on a C-Stand that can be used by the focus puller, or used for playback to verify focus. Some computer monitors can be used for this purpose, although they will not be color accurate. The HP DreamColor, however, is an exceptional and low-cost choice.
The viewing angle is the maximum angle at which the image can be clearly viewed. A wider maximum viewing angle is key to being able to use the monitor in situations where the monitor's position and angle changes as the camera moves, such as on a stabilizer. Some monitors have such a narrow viewing angle that they cannot be viewed properly by two people at once, because both would need to face the monitor head-on to see the image clearly. Some monitors list the side-to-side as well as the top-to-bottom viewing-angle measurements.
The contrast ratio of a monitor is the ratio between the darkest and brightest areas of the screen. Low contrast ratios won't be able to represent the full range of tones in the scene correctly, and the whites and blacks won't be as deep.
The brightness of an LCD monitor is measured in nits, a unit equal to candela per square meter, although a monitor that has poor contrast may be overwhelmed by incident light regardless of its sheer output. Some monitors have a brightness setting that can be adjusted, although many monitors simply amplify the video signal's brightness, instead of adjusting the backlight—a more accurate solution.
The response time is the time it takes for individual LCD crystals, or pixels on the monitor, to turn on (to complete white) or off (to complete black). There are two measurements taken, one for when the pixel turns on ("rise") and one when it turns off ("fall"). LCD monitors with a slow "fall" response time display image ghosting or blurring around moving objects. Some LCD monitors are also listed with a gray-to-gray measurement, which will typically be slower than white and black response times.
There are essentially two options when it comes to a screen coating on field monitors: glossy and matte. Glossy monitors may look sharper and more saturated, but they are also more sensitive to reflections that can sometimes make the monitor unviewable at certain angles and brighlty lit scenes. Glossy screens also tend to make dust on the screen more noticeable and scratch more easily.
Matte-coated monitors do not look as sharp and saturated as their glossy counterparts, but they provide a more glare-free viewing experience and are much more suited to use in bright daylight.
Some monitors offer a “peaking” feature, which indicates what is in focus by highlighting edges when they are sharp. This can be a helpful feature when setting up a shot, or even while recording to help keep subjects in focus.
1:1 Pixel Mapping
Many monitors have a tendency to stretch or otherwise conform the incoming video signal to match the monitor's native aspect ratio and resolution. This is an inaccurate way of viewing the source video and can lead to mistakes, especially with critical focus. 1:1 pixel mapping ensures that the monitor displays the original pixels using the monitor's native pixels. If the monitor isn't large enough to display the video at its original size, the image will appear cropped or zoomed.
A false color filter found on some monitors can help set exposure more accurately by displaying the different luminance values as different colors overlayed on the image. Once the color code is memorized, it is easy to detect overexposed, underexposed and incorrectly exposed areas just by seeing the color that it produces.
All current HDSLRs have both HDMI and RCA outputs for viewing the video on an external monitor. The RCA output should be avoided because it displays a much lower-quality image than what is being recorded. This makes it unusable for judging anything other than framing. The simplest approach is to use a monitor that has an HDMI input.
Although all of the current HDSLRs use HDMI, it is not a professional cable standard and some professional monitors do not have this type of input. The cable connections do not sit securely in their sockets, which can cause dropouts in the video signal if the cable is bumped or tugged even slightly. Making matters worse, HDSLRs output the video signal only when it "senses" a monitor, so when the cable is disconnected, the HDSLR automatically diverts the video to the built-in LCD until a few seconds have passed for it to have sensed the HDMI cable again. These issues not withstanding, having an HDMI monitor is still the most straightforward and cost-effective approach.
As an added benefit, monitors with a DVI input can be used as a second computer monitor in the field or in the studio. Note: Some monitors that do not have an HDMI input may come with a DVI to HDMI converter cable. In some cases, this will downscale the originating 1080 video signal to 480, so it's best to avoid conversion cables.
Some monitors have the ability to pass the incoming video signal on to an output. This is called a loop through. However, monitors do not usually have this feature when using HDMI. If multiple monitors are required, the best option is to convert the HDMI into an SDI connection using a converter box. The price is similar to an HDMI splitter box, and typically will provide two SDI outputs. If more than two monitors are set up, be sure to choose a monitor with a loop-through feature, which can continue to send the video signal to an SDI output.
There are two ways that a monitor's settings can be adjusted: direct access controls and through an onscreen menu. Direct access buttons and controls are ideal for quick changes during a shoot, while menus are more time consuming and inefficient for accessing often-used settings.
Depending on the need for efficiency, look for a monitor that has direct-access controls for the features that will be used the most. For example, a zoom-in button can be very helpful to check focus on the fly, but if the operator has to go through a menu selection every time, it won't be used as often. Some monitors can also save user settings, which can be very helpful for working with specific camera setups.
The aspect ratio is the relative size of the height and width of the video image, so even if the size of the image changes, the ratio stays the same. There are two components to consider with aspect ratios: the native aspect ratio of the screen and the ratios that the monitor accepts that can be properly scaled (if they don't match the monitor's native ratio). The two most widely used ratios are 4:3 (an older TV standard) and 16:9 (widescreen, standard on HDTV and DVDs). Ideally, a monitor should be 16:9 because most video is now shot in this aspect ratio; however, it's worth noting that with most HDSLRs, the full 16:9 size of the screen will be unused due to the image being framed with black bars and camera information (unless the monitor can zoom in and crop the image).
Camera-mounted monitors can be powered by batteries or by an AC adapter. If several batteries for a video camcorder are available, it might make sense to get a monitor that comes packaged with a compatible battery mount.
Some monitors have a built-in voltage regulator so they can accept a range of voltage inputs, which offers the most flexibility. This is especially desirable if a central power source will be used, like a brick battery system. Note: Verify that both the power jack and voltage are compatible with the battery system being used.
Camera-mounted monitors have a standard 1/4"-20 threaded mount on the bottom, top and/or sides of the monitor for use with a mounting arm, shoe mount adapter (to mount on top of a camera) or use with an adapter to mount on a light stand.
Although a large monitor provides a better and more accurate viewing experience, they weigh down a handheld rig significantly when the battery weight is factored in. The kind of shooting that will be done needs to be considered. For example, if a dedicated focus puller will have a monitor in addition to the one mounted on the camera (for the camera operator's viewing), then the camera-mounted monitor may be a smaller, lightweight unit with just enough features and resolution for composition. Another factor to consider is the type of monitor arm that will be used. Make sure the arm can support more than the combined weight of the monitor and batteries, because the force of moving the rig also adds to the static weight on the arm.
HDMI is, broadly, a consumer equivalent to SDI. Both transmit uncompressed HD video. SDI was designed to be transported long distances over existing video infrastructure that used locking BNC connectors and sturdy coaxial cabling, whereas HDMI is designed to connect consumer equipment within the confines of a desktop or TV cabinet, and is considerably less sturdy. HDMI is the connection that all current HDSLRs and most consumer electronics use.
All HDSLRs use a type-C HDMI connector, which is smaller than the standard type A, so special cables are required. Because of the position of the HDMI input on HDSLRs, as well as the unsecured design of HDMI, the ideal cable would be a vertically angled Type C to Type A cable, but these are not as common.