What is IMAG?

IMAG is Image MAGnification.

Any time you have someone on stage, and there's a screen next to them, or elsewhere, 用摄像机拍下了同一个人的影像, this is called IMAG. The purpose is to MAG统一人物的“形象”，这样离舞台远一点的人就能更容易地看到他们. The usage of IMAG is very common in corporate events, the hotel and meeting industry, faith-based production, etc.

Faith-based IMAG at Green Acres Baptist Church

IMAG is very important. 当观众能轻松自如地看到演讲者讲话时，观众和演讲者之间就会产生强烈的关系. It's more powerful. 面对面的会议比电话会议更有效. 即使是舞台演员也知道不要面朝舞台后面念台词. 如果观众看不到你的嘴在动，他们就会觉得好像听不见你说话一样. 所以这是一种常见的戏剧“欺骗”，在说话时倒着走或斜着走. Being seen is THAT important.

What IMAG is, and What it Isn't

在许多情况下，屏幕上的图像并不总是扬声器的放大镜头. 这是因为同样的提要也是在网络上向用户传输的内容, or archived as a documentation of the event, so there will need to be wide shots, shots of the audience, close-ups of product, pre-recorded video segments, slides, graphics, and a whole lot more.

在大屏幕上播放的PowerPoint或其他基于计算机的幻灯片本身通常不被称为imagg. Neither is video playback only. 但是当你在舞台上用相机拍摄的时候, it all becomes IMAG, 视频播放和幻灯片演示通常会伴随着它.

There are two key ingredients that make it IMAG:

• cameras with long lenses
• big projection screens

Cameras and Lenses for IMAG

To provide the "magnification" part of IMAG, 你通常需要在礼堂中央安装一个广播摄像机, with a big/long lens on it. 这种镜头一般不适合拍摄距离小于20英尺的物体. 它的设计目的是把很远的东西拉近. 想想那些可以从球场另一端向你展示四分卫脸的大镜头. Those are generally 80x, 100倍或更大的镜头，并在三脚架上操作，三脚架的设计是为了保持巨大的镜头, and THEN you attach the camera.

Canon DigiSuper72 lens (© 2011 CVM PRODUCTIONS, INC.)

所以，从技术上讲，在200英尺的场内LED墙上看到四分卫的脸是图像.

如果你有一个较小的摄像机，只有一个20倍的镜头，开始在一个合理的宽度, 你需要做以下一件(或多件)事情来获得你需要的长变焦，在一个相当大的场地上获得合适的图像:

• add an optical doubler on the front of the lens
• replace the lens (if possible) with a longer one
• move the camera closer to the subject

光学倍增器是一大块玻璃，可以作为2倍的“双筒望远镜”，将现有镜头的变焦倍数提高一倍. 你把它固定在你现有的镜头前，把远处的物体拉近，让它们看起来更大. 如果你经常这样做，买一个是有意义的. You can also rent them. 下图是施耐德光学公司的Century Converter光学倍频器.

施耐德光学世纪转换器为松下HVX200光学倍频器

On removable-lens cameras, 通常有各种各样的镜头可以用来代替相机附带的库存镜头. Very often, these lenses are available from rental houses, like Bexel and others, that will ship then nationwide, or even internationally. 你可以在你的活动中使用镜头，然后把它寄回来.

Canon 33x11 lens in case © MK Video Inc.

Lastly, 你可以在房间中央搭建一个摄像平台, 或者甚至把它放在离舞台更近的地方，把它放在离地面更低的地方，这样就不会挡住太多人的视线. This way, 你可以用说话人的脸填满画面, and when that image is put on a 20' screen, 坐在房间后面的人都能清楚地看到演讲者在讲话.

Bringing the camera closer to the subject. Image © Analog Way