What’s the difference and when would I need varifocal lenses?
Part 1 – What’s the difference?
A fixed lens doesn’t let you adjust the focal length, angle of view, and level of zoom. Almost all fixed lens cameras have a wide angle.
With a varifocal camera, you can adjust these things. Let’s look at some examples of what this means:
This an image from a fixed lens (The Warrior ), which is fixed at 3.6mm 4mm | 12mm| 8mm with someone standing a feet away
By increasing the focal length, you get a much better image of the man/license plate. At 10 feet, this doesn’t matter very, much but at larger distances (which we will show in a second) this can mean the difference between identifying a suspect and not getting a clear enough picture of their face.
Not just two settings
A varifocal camera allows you to adjust between its top and bottom limits on its view angle. This means that you have the ability to manually set both the view angle and level of zoom. Have a scenario where you need to zoom in on a gate or other access point? Use the 12mm setting (12 degrees and about 4x zoom). Need a wide angle view? Go with 2.8 mm (109 degrees). Need something in between? Try 6mm (~45 degrees) or 9mm (~30 degrees).
How to Adjust the Lens
As of 2018 all SCW adjustable cameras feature motorized zoom..This means that you can control the zoom and focus from the camera or NVR. No ladders, no tiny knobs, just simple. easy, and auto focus capable cameras.
Distance – When vari-focal cameras become necessary
At about 50-100 foot a wide angle lens 1080P camera, will not do a tremendously good job at identifying faces. (At about 20 foot, a standard definition camera will also not work identify faces, but if you are willing to pay for a vari-focal standard definition camera you should go HD wide angle – for about the same price as a standard definition vari-focal, you get a higher resolution picture that extends the distance that you can identify faces while not giving up any the wide angle view).