A camera lens has a focal length of 180.0 mm and an aperture diameter of 16.36 mm. (a) What is the ƒ-number of the lens?

Verified step by step guidance

1. Identify the formula for the f-number of a lens, which is given by: f-number = focal length / aperture diameter.
2. Substitute the given values into the formula. Here, the focal length (f) is 180.0 mm and the aperture diameter (D) is 16.36 mm.
3. Perform the division of the focal length by the aperture diameter to find the f-number.
4. The result from the calculation will give you the f-number of the lens, which indicates the ratio of the lens's focal length to the diameter of its aperture.
5. This f-number helps in determining the amount of light that can enter the lens, affecting the exposure and depth of field in photography.

Key Concepts

Focal Length

Focal length is the distance from the lens to the point where light rays converge to form a clear image. It is a critical parameter in lens design, influencing the lens's magnification and field of view. A longer focal length results in a narrower field of view and higher magnification, while a shorter focal length provides a wider field of view.

Aperture

The aperture of a lens is the opening that allows light to enter. It is typically measured in diameter and affects the amount of light that reaches the camera sensor. A larger aperture (smaller ƒ-number) allows more light, which is beneficial in low-light conditions, while a smaller aperture (larger ƒ-number) increases depth of field, making more of the scene in focus.

ƒ-number (F-stop)

The ƒ-number, or F-stop, is a dimensionless number that represents the ratio of the lens's focal length to the diameter of the aperture. It is used to quantify the lens's light-gathering ability and depth of field. A lower ƒ-number indicates a larger aperture, allowing more light and creating a shallower depth of field, while a higher ƒ-number indicates a smaller aperture, allowing less light and increasing depth of field.