Focal Ratio Calculator

Calculate Focal Ratio (FR)



Formula

The formula to calculate Focal Ratio (FR) is:

\[ FR = \frac{FL}{A} \]

Where:

What is Focal Ratio?

The Focal Ratio, often referred to as the f-number or f-stop, is a dimensionless number that describes the ratio of the focal length of a lens or mirror to the diameter of the aperture. It is an important parameter in photography and optics, affecting the depth of field and the brightness of the image. A lower focal ratio indicates a wider aperture, allowing more light to enter and resulting in a shallower depth of field.

Example Calculation

Let's consider an example:

Using the formula to calculate Focal Ratio:

\[ FR = \frac{200}{50} = 4 \]

This means that the Focal Ratio (FR) is 4.