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All about irises: fixed iris, manual iris, auto iris and P iris

Published by Margeaux on January 20, 2012 8:59 AM

Security cameras feature an iris built into their lenses that control how much light affects their sensors. Clearly, the iris is a vital component of a camera, and there are several types of irises to consider when comparing security cameras.

Fixed Iris

Fixed iris cameras are ideal for environments with unchanging light, making them a good choice for indoor use. These irises are preset and cannot be adjusted during installation.

Manual Iris

Manual irises are similar to fixed irises, except that they can be manually adjusted. This is usually only done during installation, as it is highly inconvenient to do so while the camera is already in use. Likewise, cameras with a manual iris are best utilized in situations with constant light, such as indoors.

Auto Iris

Auto irises, also called DC iris and video iris, have a motor-driven iris that automatically adjusts according to light levels. Auto irises perform well in outdoor and indoor locations.

P Iris

P stands for precise, and these irises are top of the line. P irises act like auto irises, but deliver even better image quality. Using software, P irises make finite adjustments to react to changes in light. Lenses featuring P iris deliver images with superior clarity and contrast. P iris is ideal for outdoor or indoor use, and essential in scenarios with quick changing light.

Unlike auto irises, the degree to which P irises close due to bright conditions is restricted. This prevents the blurring and diffraction that can happen when an auto iris lens is confronted with a very bright light source.

Many megapixel cameras feature a P iris lens, as their sensors have smaller pixels which are more prone to diffraction if light is not precisely controlled.

Learn more about IP camera irises in our technology section: What is a camera iris?