What Does The Mm Number Mean On A Camera Lens ?

The mm number on a camera lens refers to the focal length of the lens. It is a measurement of the distance between the lens and the image sensor when the lens is focused at infinity. A smaller mm number indicates a wider angle of view, while a larger mm number indicates a narrower angle of view and greater magnification. For example, a 50mm lens is considered a standard lens, while a 200mm lens is considered a telephoto lens. The mm number is an important factor to consider when choosing a lens for a specific type of photography, as it can greatly affect the composition and perspective of the image.

1、 Focal length measurement

The mm number on a camera lens refers to the focal length measurement of the lens. 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 and magnification of the lens.

A lower focal length, such as 18mm, will have a wider angle of view and can capture more of a scene in a single shot. This makes it ideal for landscape and architectural photography. On the other hand, a higher focal length, such as 200mm, will have a narrower angle of view and can magnify distant subjects, making it ideal for wildlife and sports photography.

It is important to note that the focal length measurement is not the only factor that determines the quality of a lens. Other factors such as aperture, lens construction, and image stabilization also play a significant role in the overall performance of a lens.

In recent years, there has been a trend towards more compact and lightweight lenses with wider apertures and improved image stabilization. This has led to the development of mirrorless cameras and lenses, which offer high-quality performance in a smaller and more portable package.

Overall, understanding the focal length measurement of a lens is essential for selecting the right lens for a particular photography style or subject.

2、 Determines field of view

The mm number on a camera lens refers to the focal length of the lens. It determines the field of view that the lens can capture. A lower mm number indicates a wider field of view, while a higher mm number indicates a narrower field of view. For example, a 24mm lens will capture a wider field of view than a 50mm lens.

The field of view is an important consideration when choosing a lens for a particular type of photography. A wide-angle lens with a low mm number is ideal for landscape photography, as it can capture a large area of the scene. On the other hand, a telephoto lens with a high mm number is better suited for capturing distant subjects, such as wildlife or sports events.

It is important to note that the mm number on a lens is not the only factor that determines the field of view. The size of the camera's sensor also plays a role. A camera with a smaller sensor will have a narrower field of view than a camera with a larger sensor, even when using the same lens.

In recent years, there has been a trend towards using zoom lenses with a wide range of focal lengths. These lenses offer the convenience of being able to zoom in and out without having to switch lenses. However, they often sacrifice image quality for convenience, and may not be suitable for professional photographers who require the highest level of image quality.

3、 Affects depth of field

The mm number on a camera lens refers to the focal length of the lens. It is the distance between the lens and the camera's image sensor when the lens is focused at infinity. The focal length determines the angle of view and magnification of the lens. Affects depth of field, which is the range of distance in a photograph that appears to be in sharp focus.

A lens with a shorter focal length, such as a 24mm lens, has a wider angle of view and can capture more of a scene in a single shot. This makes it ideal for landscape photography or capturing large groups of people. On the other hand, a lens with a longer focal length, such as a 200mm lens, has a narrower angle of view and can magnify distant subjects, making it ideal for wildlife or sports photography.

In addition to affecting the angle of view and magnification, the focal length also affects the depth of field. A lens with a shorter focal length has a wider depth of field, meaning more of the scene will be in focus from foreground to background. A lens with a longer focal length has a narrower depth of field, meaning only a small portion of the scene will be in focus, with the rest appearing blurred or out of focus.

It is important to note that the aperture of the lens also plays a significant role in determining the depth of field. A wider aperture (lower f-stop number) will result in a narrower depth of field, while a smaller aperture (higher f-stop number) will result in a wider depth of field.

In recent years, there has been a growing trend towards using lenses with wider apertures and shorter focal lengths for portrait photography. This allows for a shallower depth of field, which can create a more dramatic and artistic effect by isolating the subject from the background. However, it is important to use this technique carefully and with intention, as it can also result in a loss of detail and context in the photograph.

4、 Longer mm = more zoom

The mm number on a camera lens refers to the focal length of the lens. Focal length is the distance between the lens and the camera's sensor when the lens is focused at infinity. The mm number is an indication of how much the lens can magnify a subject and how wide the field of view is. In general, longer mm numbers mean more zoom and narrower fields of view, while shorter mm numbers mean less zoom and wider fields of view.

For example, a 50mm lens is considered a standard lens and is often used for portraits and street photography. A 200mm lens, on the other hand, is considered a telephoto lens and is often used for sports and wildlife photography. A 10mm lens is considered an ultra-wide-angle lens and is often used for landscape and architectural photography.

It's important to note that the mm number alone doesn't determine the quality of a lens. Other factors such as aperture, image stabilization, and lens construction also play a role in the overall performance of a lens.

In recent years, there has been a trend towards smaller and lighter camera gear, including lenses. Manufacturers have been developing lenses with shorter mm numbers that still offer high-quality images and versatile shooting options. These lenses are often referred to as "pancake" or "compact" lenses and are popular among photographers who value portability and convenience.