Some time ago, you asked about what telephoto focal length would be best. As you know, I was the first person on DCT to demonstrate a telephoto dash cam
six years ago. Over time, my views about how long a telephoto lens should be used have evolved. I've learned that it depends on how you want to use the camera and what your personal needs are. These days I prefer a wider, less powerful lens because I often travel on smaller two lane roads and I find it useful to capture cars and license plates of vehicles coming towards me in the other lane. If I have too much magnification, I miss that.
Originally, I preferred a stronger magnification like this:
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These days I use a less powerful 8mm lens that allows me to capture the oncoming lane as well. I sometimes even turn the lens slightly to the left to enhance oncoming lane capture.
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Here is the corresponding frame from the Viofo A119 V3 for context.
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If you are finally going to produce a commercial telephoto dash cam option, perhaps a module for the A139, I would recommend doing two focal length options, one with a longer lens and one slightly wider so the buyer can decide which version works best for his particular driving conditions.
Some people may want both which could lead to additional sales.