What does it mean to change the focal length of shooting?

Photography is full of professional terms and complex operations. Previously we learned about aperture, shutter, ISO exposure triangle and other knowledge. Today, let’s learn what the focal length is in photography. This term comes up a lot, especially when we're choosing lenses, so it's important to be familiar with it if you're interested in photography.

The so-called focal length refers to the distance from the center of the lens to the focus where the light is focused. Simply put, the focal length is the eye of the lens and determines the range of the view.

And here, we also need to understand what the focus is? When light rays enter the lens, they pass through the glass and are refracted to converge into a point, which is where the light data is collected to form a clear pattern for the sensor to record. So manufacturers measure focal length based on the distance between the lens and the focal point.

Focal length is measured in millimeters. For example, the focal point of a 50mm lens is 50mm from the lens. In the picture above, the focus point is marked "F" and the focal length is marked "".

So how to choose the appropriate focal length? This is mainly adjusted according to your shooting scene. A shorter focal length will make your subjects appear smaller, while a longer focal length will make them larger. A shorter focal length also means you can shoot from a wider angle of view, while a longer focal length will result in a narrower angle of view. Simply put, focal length determines the magnification of the image. We can use a shorter focal length to take landscape photos, and choose a longer focal length to take clear pictures of distant objects, such as trees, birds, etc.

According to the focal length, we can generally divide it into four types of lenses, namely ultra-wide angle (focal length below 24mm), wide-angle (focal length between 24-35mm), standard (focal length between 35-85mm), Telephoto (focal length above 85mm).

In addition to using the length of the focal length to take ultra-wide-angle and distant photos, the focal length can also help take good-looking bokeh (of course, the quality of the bokeh mainly depends on the aperture), and a longer focal length can also help you take better-looking bokeh. Depth of field will be reduced, separating the subject from the subject with a softer blur.

Therefore, on smartphones, we can also see that manufacturers will equip a telephoto macro lens to take better macro photos