The Auto Iris is electronically controlled. This allows the camera to maintain the lighting level by changing the spatial dynamic of the iris to obtain optimal quality imaging. It is applicable in situations where lighting conditions vary continuously. An auto iris allows the camera to adjust to get the best picture in a given lighting condition. The Auto Iris can be applied to both fixed and varifocal lenses.The Auto Iris feature is highly flexible in producing consistent video signals as it can adjust to drastically changing light levels. An electronically controlled iris is perfect to maintain one consistent light level making them ideal for outdoor use or any other applications.
AES - (Automatic Electronic Shutter) is used in cameras where the iris remains fixed allowing the shutter speed to change with response to the amount of perceived light to keep the signal output at the best possible level. AES allows a fixed iris to adapt automatically to different lighting conditions without the need of being automated. When the shutter speed increases, the light passing through the lens is decreased and the cameras sensitivity is reduced. When the shutter speed is decreased, a larger amount of light enters the iris. For fast moving objects the shutter speed can also be increased to provide a freeze effect in order to provide higher resolution images.Although both features are intended to account for changes in the lighting environment, they both have their benefits and weaknesses. Whereas the Auto Iris is used for optimal lighting maintenance, it is slower to react than the Auto Electronic Shutter. Furthermore, the superior quality imaging of the Auto Iris often comes at a higher price due to its much more complicated structure. Both features are very important in achieving quality imaging in varying light, and neither is better than the other. They are simply better suited in different situations.