How Far a 12mm Camera Can See and How to Calculate FoV (PPM and PPF)
Customers often ask me: “How far can a camera with a 12mm lens see?”
A difficult question made easy to answer. A 12mm lens can see 12 meters, just as a 4mm lens can see 4 meters. You can’t prove me wrong because this question is ambiguous with uncertainty. Are we looking at license plates or faces? To tackle this, I found a free tool online that I recommend customers use:
Please visit: CCTV Lens Calculator — New generation of Lens Calculators for CCTV (jvsg.com) ，
In order to precisely measure license plates or faces, the CCTV industry has introduced measurement units called PPF (Pixels per Foot) and PPM (Pixels per Meter). This allows CCTV cameras to maintain the resolution of the captured object while expanding the Field of View (FoV). This enables the cameras to cover a wider area while retaining clarity on the subject being captured.
How to Calculate PPF & PPM
“Pixel per foot” (PPF) is a term used to describe the resolution of an image or display, especially concerning spatial and dimensional measurements. It represents the number of pixels contained within one foot of length, serving as a measure of resolution. For instance, if an image has a PPF of 10, it means there are 10 pixels within every foot, offering a finer level of image detail.
Pixel per foot (PPF) and Pixel per meter (PPM) are used to compute an estimated value based on the camera’s pixels compared to the Field of View (FoV) of the camera. As per the diagram provided, considering the lane is 20m / 65.6ft wide and the camera width resolution is 1920 pixels, measured via Google Maps to ascertain the road width of 20m / 65.6ft.
The entire view of the camera can cover:
1920 / 446 (pixel) * 20m = 86m or 1920 / 446 (pixel) * 65.6ft = 282.2 ft.
Example 1: Using a 5.3mm lens, a person is 40m away, and the width of the person in pixels is 26px.
26px / 0.45m (the width of the person) = 57.7 PPM or 26px / 1.47ft = 17 PPF
Example 2: Using a 5.3mm lens, a person is 50m away, and the width of the person in pixels is 19px.
19px / 0.45m (the width of the person) = 42.2 PPM or 19px / 1.47ft = 12.9 PPF
Example 3: Using a 5.3mm lens, a person is 60m away, and the width of the person in pixels is 16px.
16px / 0.45m (the width of the person) = 35.6 PPM or 16px / 1.47ft = 10.9 PPF
Epilogue: Why PPF and PPM Matter
As AI camera technology advances, users are increasingly concerned about the accuracy of wide-angle camera AI recognition. This has led to the establishment of specifications in bids to ensure precision. To accurately describe and measure captured objects such as vehicles or people, the definitions of PPF and PPM are crucial for achieving accuracy in practical applications.
