In so many years of TV production the question still comes up.. "How much magnification will I need to get a tight headshot at 100 feet with this ENG 2/3" b4 lens mount eng camera? 18x? 20x? 40x? Can I use a 2x extender?
I never have a quick answer and many times after the setup it's decided that a longer lens is indeed needed, and it's back to the shop to pickup the Fujinon 42x and heavier set of sticks.
Is there a chart for dummies that can simply show both the experienced and newbies how tight a cam op can frame a subject with any given lens magnification?