Focal length is the distance between the lens and the camera’s image sensor when the lens is focused at infinity. It is measured in millimeters and determines the angle of view of the lens. Focal length affects how much of the scene you can capture in a single shot and how distant objects appear in your photos.

Here are some key things to know about focal length:

1. Short focal length: A short focal length, such as 18mm, is considered wide-angle and is great for capturing a wide field of view. They are ideal for landscape, architecture, and interior photography.
2. Medium focal length: A medium focal length, such as 35mm or 50mm, is considered standard and is great for general-purpose photography. They can create natural-looking images and are ideal for portrait, street, and documentary photography.
3. Long focal length: A long focal length, such as 85mm or 200mm, is considered telephoto and is great for capturing distant subjects. They can compress the background and create a shallow depth of field, making them ideal for sports, wildlife, and portrait photography.
4. Zoom lenses: Zoom lenses have a variable focal length and allow you to adjust the angle of view. They are great for travel photography or situations where you need to quickly switch between different focal lengths.

It’s important to note that focal length alone does not determine the quality of your images. Other factors such as aperture, image stabilization, and lens quality also play a significant role in determining the quality of your photos.