FOV Test - A119 Mini - A119 Mini 2 - A139 Pro - WM1
It is certainly a useful comparison to see the differences between AOV of these three cameras.
I recall that recently you were puzzled that all three of these cameras claim to have an Angle of View of 140º yet they all yield different coverage. There is a simple explanation for this that needs to be taken into consideration when comparing different cameras.
All three cameras, (Mini, Mini 2, and A139 Pro) have a listed specification FOV of 140° degrees. However I’m seeing they are all different with the Mini being the narrowest, the A139 Pro being the widest, and the Mini 2 somewhere in the middle.
Each of these cameras uses a different sensor and/or different resolutions. Even if all three cameras have the identical 140º lens on it the result will be that the apparent AOV will appear different. A slightly bigger or smaller sensor will yield a different result, as will the same sensor set for either 2K or 4K. There is really only so much
@viofo as a manufacturer can do to be exactly precise when they present us with these specifications. It is one thing for a manufacturer to provide the exact and precise AOV when you have a camera and lens that costs thousands of dollars and another when you have a consumer product like a modestly priced dash camera where each lens AOV would need to be precision calculated for each sensor size. You can get very close however. I believe that close is good enough for most dash cam buyers, although some of us can be pretty fussy about these things.
A bigger or smaller sensor will yield a different result, because each lens projects an image circle of fixed size called "the
circle of coverage". This circle is a cross section of the cone of light projected onto the sensor by the lens. To work properly the "circle of coverage" needs to be larger than the size of the sensor to avoid vignetting. The same circle of coverage projected onto a smaller sensor will yield an image with greater magnification and when projected into a larger sensor will provide an image with less magnification, hence the apparent AOV will be different in each camera given the same lens on different sensors. The resolution of the sensor is also a factor.
This topic comes up here on the forum from time to time. Here is a graphic I created several years ago to illustrate how this concept works with two sensors of different sizes with the same lens. This hypothetical "lens" has only one image circle of coverage (also called the circle of illumination) yet yields different magnifications or image AOV depending on the size of the sensor.