juky wrote:
> Dear all,
>
> I have a mathematical question regarding relation between zoom factor
> and magnification. My digital video camera shows me the current zoom
> factor selected. Focal is 3,5-91 mm. I'm looking for mathematic
> formulas which give me the zoom factor to be selected so that an
> object in the shot will appear halved, double, etc. I premise the
> object distance is unknown.
> Is there any way?
>
What do you mean by "zoom factor"? Do you mean focal length?
Mathematically, it's basically similar triangles, and you need to know
the dimensions of the sensor image area. As a rough approximation, at
longer focal lengths, doubling the focal length will make an object
appear twice as big (linear dimensions) in the frame.
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