As digital security cameras continue to advance even more every day in picture quality and DVR compression, digital and optical zoom lens. When we looking on security camera lens you will notice that the specifications for digital cameras lens or their descriptions measure the lens as a number of times. For example a lens may be described as 10x or 22x. This spec referred to the zoom ratio.
The Basics rules of Calculating the Number of Times or Zoom Ratio.
Security cameras have feature that called a focal length. This spec applies to any security camera regardless of the type of lens. The focal length is measure the distance from the optical center of the lens to the camera's focal point.
For security camera without a zoom lens the focal length is called fixed lens as the lens never changes position. Therefore the distance or focal length between the lens and sensor stayed the same. Security camera which have the ability to zoom in and out are called Vari-Focal security camera.
When using security camera zoom lens the position of the lens changes as you zoom in or out. As you zoom in the focal length increases. As you zoom out the focal length decreases. The focal length of security camera is always measured in millimeters. The 5 mm represents the minimum focal length when the zoom is not being used. The max 50mm is the focal length when the zoom is fully extended.
It is common to see two zoom ratios in a security camera spec. One is for optical zoom already discussed above and the second is for digital zoom. Digital zoom is completely different to optical zoom. Rather than using the lens to zoom in or out, security camera digital zoom is carried out by software inside the camera or the DVR system. Basically the software increase the size of the image to give the impression of zooming in. stretching the picture size will usually create decrease in picture quality. Therefore optical zoom is considered far superior to digital zoom.
On a security camera offering both optical and digital zoom you can use both simultaneously. For example a camera with 10x optical zoom and a 4x digital zoom can give a combined total of 40x zoom.
Manual Iris Lenses are perfect for stable interior environment with constant good condition light, such as interior stores, malls, libraries, and offices. Manual Iris Lenses are best suite for these type of locations with stable light condition, The auto iris needs to setup ones on the initial setup of the security camera installation.