Our camera has an iris, just like a human eye has an iris. When closed, the iris lets in a small amount of light, and then lets in much more when opened. Unlike the one in your own eye, our iris never closes, always allowing in the optimal amount of light to guarantee the brightest possible picture.
The automatic iris in the camera ensures that the optimal amount of light gets through to the ccd image processor to capture professional quality images. This means that even in low light conditions, it will still produce sharp, clear images.