Purchasing an office or apartment entry system or any other surveillance camera system can be a tricky venture, its intricate parts interact in these systems, making it excessively difficult to understand. A lot of factors including camera, DVR, accessories, and monitor all affect the final recorded image quality. An accessory that can hesitate a potential buyer or owner is the lens of the security or surveillance camera. Along with the compatibility of a particular security camera, a lot of factors might affect the proper functioning of the security system such as the unsuitable lens of the camera which can affect the image quality. Hence, before investing in a security system, one should familiarize themselves with the quality of the ideal camera lens. Important considerable functionalities to look for in a security system lenses are:

Focus length and field of vision
Image format
Varifocal, monofocal, and zoom lenses
Aperture
Iris