My goal is to put a lens or an array of lenses in front of my actioncam to use its high resolution for recording of undistorted normal-eyed footage, to avoid having to buy two cameras for the occasional video blog.
Now I looked into it and what I can choose from are frequency admission, focal length and diameter.
What do I know about my actioncam? I has a 175° - f/2.8 lens in it. I know its sensor has a ratio of 4/3.
How do I figure out, which lens(es) of what diameter(s) in which distance(s to each other) to use?