Scanning the World with Pan/Tilt/Zoom (PTZ)  

July 01, 2016

PTZ is one of those acronyms that photography and the video world use to describe the movement of the camera. It is one of the simplest concepts of cinematography and yet one of the most powerful.

There are technical definitions for each of these movements but for our purpose today we will try to keep it simple.
   • Pan is rotation of the camera left and right along the horizon.
   • Tilt is changing the vertical angle of the camera up and down.
   • Zoom is changing the lens so that the scene appears closer or farther away.
Each of these effects is created without physically changing the location of the camera; rather the camera angles are repositioned or the lens’s focal point is altered.

Relating to Real World Subjects

If you have an interest in mathematics and geometry then consider the relationship between PTZ and 3 Dimensional Graphing. If our camera is at the origin, then we have a great correlation with the XZ plain being our Pan area, the relationship of the Y-Axis being our camera angle of Tilt and the coordinate distance from the origin being our amount of Zoom.

PTZ can be done manually or via remote control. Cameras equipped to move via remote control are referred to as “PTZ Cameras” and are a lot more expensive than equivalent non-PTZ cameras. So why spend so much more for remote control? If you are in a school auditorium and have several students that can manually run the cameras then you don’t need remote PTZ control. On the other side if you have a limited number of people in your production team then remotely controlled cameras let one or two people control several cameras from a central location. 

Other reasons for PTZ controlled cameras include security and safety. Perhaps you want to view an area around the school for the safety of the students and staff or for the security of the building. In an auditorium or a gym you might need a view from a location that could be dangerous for someone to operate the camera such as a view from the rafters above the center court of your gym.

Who Cares

“Why do we even care about moving the cameras around? All we are doing is a newscast from a desk!” Your right, you don’t need to be concerned about PTZ. Consider though, if you are recording a drama that your students wrote or recording a sporting event, then people don’t stand still. Variety is the key to maintaining the audience’s attention with any broadcast and while you can get by with just panning right and left there is so much more to the world of video. PTZ gives you a quick and easy opportunity to capture and maintain your audience’s attention, thus making sure they stay with you and watch your broadcast to the end. 

It is hard to say that any of the three PTZ video effects are more important than the others. If the subject moves around then we Pan and Tilt to keep them in the shot. Zoom on the other hand has little to do with keeping the main subject in the view but rather in keeping the shot interesting. A close-up shot of our subject compared to a wide shot with all of the background gives us a completely different perspective and has a drastically different emotional effect. The question is: “What is the focus of the shot, not who is the focus?” We know whom we want in the shot but do we want them with the scenery around them giving us a far-away feeling? Maybe we want just them and a nearby object or perhaps a close-up of their face will give us the true emotional effect for which we are looking.

To Move or to Stay Still

Finally, it is not the ability to move the camera that is important but rather the question of if you should use PTZ. Why not, if I can do something then why would I not take advantage of it? Many videographers want no PTZ movement while a shot is live, others vote for moderation. 

If you have ever been on a boat in heavy sea swells you know about becoming disoriented possibly to the point of getting sick. The same comes from watching video that has the camera shot moving wildly across the screen, the audience will become dizzy or disoriented.

If someone is moving around a lot then zoom out to capture a larger field of view, thus requiring less movement. On the other hand if someone is sitting in a chair and not moving around at all, then you can slowly zoom out while they are talking to keep the shot interesting. A word of caution though, don’t zoom in and out repeatedly over a short period of time or your audience will quit watching.

Till next time, keep life fun and make your video shots interesting.

-by William Bolen, Videographer

 

https://commons.wikimedia.org/wiki/File:3D_coordinate_system.svg