Category PTZ Cameras

PTZ stands for “pan/tilt/zoom” and denotes robotic cameras that typically (though not always) have integrated pan/tilt motors and zoom lenses. The Sony EVI series cameras are popular examples. Pan/tilt/zoom cameras may look like outsized surveillance cameras, and in many ways, are like them. They are designed to be installed permanently and can be enclosed in dome housings for protection or aesthetics. However, the benefits of PTZ cameras are that one operator can control multiple cameras, whereas non-robotic cameras require a separate operator for each camera; and they can achieve camera angles not possible with conventional tripod setups.

PTZ cameras are commonly found in settings such as academic lecture halls and houses of worship. They are sometimes employed for video conferencing where camera control or multiple camera angles are required. PTZ cameras are also a great option for live events in venues where cameras can be permanently installed or where mounting spots are available. This last factor will be our focus here.

Live Production

The operation of PTZ cameras used in a video production environment can be broken into two concerns: camera control and video switching.

Camera Control

Although PTZ cameras are regarded as “robotic,” they are not autonomous—they cannot (yet) track a subject all on their own. You will need a controller along with a way to monitor video from each camera. Different camera systems use different control protocols, though VISCA is one of the most common. This is a serial-based protocol that is typically carried over an RS-232 or RS-422 interface. Many camera systems allow for “daisy-chaining,” such that only a single “home run” connection is required back to the controller. Alternatively, one can follow the so-called “star pattern,” where each camera is independently linked to the controller. Daisy-chaining enables more cameras to be connected to a single controller but may or may not result in simpler cabling, depending on relative camera placement.

The controller itself features a joystick for panning and tilting, as well as a zoom toggle, in some fashion. In addition, and where supported, other camera parameters such as focus and exposure can be adjusted remotely, on the fly. Some systems even offer CCU-style camera setup controls to make calibrating all cameras to match easier.

Keep in mind, PTZ cameras aren’t motion control rigs. You may not achieve the finesse of feathering or control precision a good fluid head tripod provides, so it’s best to align your shot before cutting to that camera and keeping the camera “locked off” while it is live.

Monitoring

Live video switchers will often provide a quad- or multi-view split screen output so you can view all the video sources on a single monitor. One option for monitoring is to let the PTZ operator tap this feed. Since non-PTZ sources may be included, doing so may be non-optimal for larger productions. A dedicated multiview to combine the PTZ images may be preferable. In addition to the multiview, you may want a full-screen preview of a single camera. A low cost “hard-cutting” switcher may be all you need for this purpose. However, with such a switcher there will be a momentary loss of signal, so it should not be used where rapid on-they-fly switching is required. This is especially true with HDMI signals.

For best practice, ensure the signal going to this switcher is downstream from any appliances—such as the live switcher—that may be broadcasting live video. With SDI, your best signal choice for live broadcast, the video signal is easy to split or route, so the best plan is to split the camera feeds before they reach either the live switcher desk or the camera controller’s desk. This way, a fault on the live switcher’s end won’t mess up the camera operator while a fault on the camera operator’s end won’t mess up the live feed.

Video Switching

Since PTZ cameras typically feature standard video outputs, which may include SDI, HDMI/DVI, or legacy composite video, they will hook up to a live video switcher just as a non-remote camera would. SDI is your best bet. HDMI/DVI-based PTZ cameras are often lower cost than their SDI equivalents while outputting the same video quality. Unfortunately, HDMI is not accommodating when it comes to long cable runs. In addition, the handshake procedure HDMI requires increases latency when using it in a live-switching context. Analog is friendly for long cable runs (assuming you use baluns, discussed below) and boasts low latency since there is no handshake or other digital processing in the pipeline, but the quality is inferior and few switchers offer analog inputs these days, though mini converters are available.

The choice of live production switcher will depend on the camera signal as well as other factors; the PTZ camera is a video source just like any other. You will need to think about the number of cameras, as well as other video sources, such as computer graphics, that you may wish to integrate into the program. Also, PTZ cameras rarely feature microphones or even the ability to pass audio, so you will need a separate audio source, such as a tap from the venue’s PA system, to include an audio element in your program.

Installation and Cabling

One of the biggest virtues of PTZ cameras is flexible mounting. Basic installation requires a flat wall mount. Many models can be inverted for “upside-down” ceiling mounting directly to a junction box. (Ensure when installing the camera, it is set to the correct mode, as accessing it later to “flip” the picture may be challenging.) Additionally, there is a wide variety or arms, domes, and other mounting solutions that are available. Some mounts even thread onto standard NPT 1.5″ pipe, allowing you to repose projector and AV mounts. Weatherized housings or even weatherized cameras are available for outdoor use.

Apart from the mount, you will have to think about cabling. Generally, there will be a separate connection for video, control, and power.

Because of the distances involved, more than just a simple cable may be required to get the video and/or control signal from A to B. Cables act as antennas; the more radio interference they pick up, the more noise gets introduced into the signal. With analog signals the quality simply degrades, but with digital you will experience much less tolerable dropouts and, finally, complete signal loss. The most popular remedy is the balun. Baluns are essentially cable adapters that convert an unbalanced cable—for example, RG-6—to use as a balanced cable, usually Ethernet/CAT5 (some systems require CAT6 or CAT7). Baluns are available for basically every video signal type out there, as well as serial control signals such as RS-232 and RS-422. Since digital video, especially HD and high-resolution digital video, requires a high bandwidth, an alternative to use where baluns provide insufficient length is fiber optic.

While baluns take care of video and control, there is still the matter of power. If an AC outlet is nearby, you may find the best option is to plug the camera directly in with an AC adapter. In many cases, however, you will need an electrician to run some custom wiring for power, as well. Some camera systems, especially those that are network controlled, support POE (Power over Ethernet), in which case the control and power will share the same connection.

By the way, one can also place a PTZ camera on a tripod for a non-permanent solution that enables remote camera control.

Angle of View

An important factor to consider when selecting a camera is lens characteristics. Just as video projectors have different throw ratios, PTZ lenses have different angles of view. Most PTZ cameras are fixed-lens, which means you will be stuck with the lens that comes with the camera. Based on where the camera will be placed, ensure the lens is wide enough to give you sufficient coverage when zoomed out, while telephoto enough to get the close-ups you want when zoomed all the way in. There is a variety of lens calculator apps available that can help you make this determination.

One paradox you will encounter is that higher-end cameras tend to feature longer zoom ranges. This is because lower-cost cameras have smaller image sensors. Saying that, a magnification more than about 10x is pushing the limits of what you are likely to get away with. Any vibrations or imperfections in the camera’s pan/tilt servo motors will be very apparent at such magnification. It will also be very hard to track a moving targe treliably. If possible, opt for closer camera placement rather than greater magnification, to achieve tighter shots.

All-in-Ones

To simplify the complexity a PTZ system entails, an option to consider is Vaddio’s WallVIEW series. Built around proven PTZ cameras, such as Sony’s EVI series, WallVIEW adds modifications that adapt power, video, and control to use Ethernet cables to greatly reduce installation headaches. In addition, the system optionally adds CCU control. Rack-mountable base units provide terminal points for all the cables, CCU operation, controller input, as well as video output.

Some live video production switchers, such as Sony’s Anycast, incorporate PTZ control. The Anycast works with VISCA protocol cameras, like its own EVI series. This is a great option for small productions with limited crew.  

Alternatives

Surveillance cameras are very like PTZ cameras and may be tempting as a low-cost alternative. Unfortunately, surveillance cameras probably won’t work. They are typically self-contained systems that don’t facilitate connection with third-party video equipment. In addition, they often feature low frame rates, which reduces bandwidth and storage space. All you need to ID a shoplifter is a freeze-frame, but this won’t cut it for live video.

Motorized pan/tilt heads can be a way to adapt a regular video camera for remote operation. This may be a consideration if you need true broadcast performance or are looking for a more flexible solution than a dedicated PTZ camera. If you plan to go this route, ensure the camera functions you need can be controlled remotely and the control and video connectors can be secured so that they don’t come loose during production.

Conclusion

PTZ cameras are great for venue settings, such as concert halls, lecture theaters, or houses of worship, because they can be installed nearly anywhere while remaining out of the way. Video content from PTZ cameras can be integrated into a live broadcast just as any other video source. Since they are robotic, unless the camera is left completely stationary, you will need a camera controller and an operator to line up the shots remotely. As with other AV equipment, you will need to consider the logistics of wiring up the cameras. In many cases, baluns and Ethernet cables can be used to provide an extensible cabling solution and offer longer cable runs compared to conventional video and serial cables.