This varifocal lens features a long focal length to magnify objects from far away for unobtrusive security. The SL940A is a high-quality lens designed to allow the installer to take full advantage of the high resolution of HD and multi-megapixel cameras. The lens incorporates patented Linear Optical Technology® and can be used on cameras up to five megapixel resolution for a crisp image from edge to edge. The lens is IR corrected for use with true day/night cameras. This IR correction focuses IR light from artificial illumination at the same plane as the visible light allowing the image to remain in focus when the day/night camera switches to night mode. Unlike lenses without IR correction, the night image will not be out of focus when using IR illumination.