Cameras, FOV and ACT Revisited

I’ve been looking at all these things again recently, and after some discussion in another thread, I think SU’s FOV conversion is actually mixed up.

While researching the topic a while ago, i found one really good resource on the web here.

First of all, Filed of View is actually measured in units of length like feet or meters, and Angle of View is measured in degrees, so the term hasn’t really been used correctly by SU all these years.

Using their formulas I was able to make my own table of frequently used lenses for 35mm/Full Frame photography. (BTW, 43mm is the theoretical “normal” focal length for 35mm film frame)

Screen Shot 2022-03-19 at 2.55.09 PM

My understanding is that SketchUp uses the vertical angle of view, and that agrees with what I find when I do Match Photo. However, if you set the angle of view to 81.2°, which is the vertical AOV for a 14mm lens, SU reports that as a 21mm lens. 81.2° happens to be the horizontal AOV for a 21mm lens, so I’m wondering if this is an error in the formula that’s been used all these years by this function.

In other words, SU has been using the left column to convert AOV to focal length when it should be using the middle one because vertical AOV is what SU’s camera is based on.

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You’re a valued member of this forum! Keep up the good work! :heart:

This is an important topic for those who find themselves needing to emulate real camera lenses.

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