The formula to calculate the Effective Focal Length (EFL) is:
\[ EFL = FL \cdot CF \]
Where:
Let's say the focal length (FL) is 50 mm and the crop factor (CF) is 1.5. Using the formula:
\[ EFL = 50 \cdot 1.5 \]
We get:
\[ EFL = 75 \, \text{mm} \]
So, the effective focal length is 75 mm.
Definition: Focal length is the distance between the lens and the image sensor when the subject is in focus.
Formula: \( f = \frac{1}{\frac{1}{d_o} + \frac{1}{d_i}} \)
Example: \( f = \frac{1}{\frac{1}{10} + \frac{1}{20}} \)
Definition: Effective focal length is the focal length of a lens when used with a specific camera sensor size.
Formula: \( EFL = FL \times CF \)
Example: \( EFL = 50 \times 1.5 \)
Definition: This calculator estimates the distance to the subject based on the focal length and the field of view.
Formula: \( D = \frac{FL}{2 \times \tan(\frac{FOV}{2})} \)
Example: \( D = \frac{50}{2 \times \tan(\frac{45}{2})} \)
