Calculate Focal Length and Image Distance

Question

I need to calculate the Focal length and Image Distance of Camera by using the following parameters.

Known Parameters:

Actual Object Height ( h_o ) = 760 mm

Image Height ( h_i )= 480 pixel

Distance Between Object and Camera lens ( u ) = 1240 mm

Angle of View ( alpha ) = 34 degree

I tried to solve this problem using Magnification formula ( h_i / h_o = -v / u). Where v is Image Distance.

I calculated Image distance using the above formula.

And I am trying to find out the focal length using these value ( 1/f = 1/u +1/v)

Whether this approach is correct or not?

If it is not, Please help me to find out the focal length of the camera lens

Thanks in Advance

Answer 1

Here are the relevant formulas:

To obtain this type of numerical information, it is necessary to use the Lens Equation and the Magnification Equation. The lens equation expresses the quantitative relationship between the object distance (d_o), the image distance (d_i), and the focal length (f). The equation is stated as follows:

The magnification equation relates the ratio of the image distance and object distance to the ratio of the image height (h_i) and object height (h_o). The magnification equation is stated as follows:

These two equations can be combined to yield information about the image distance and image height if the object distance, object height, and focal length are known.

For more detail:

https://www.physicsclassroom.com/class/refrn/Lesson-5/The-Mathematics-of-Lenses