How to Read the Markings on a Lens

How to Read the Markings on a Lens


If you’re new to photography - heck, even for some photographers that have been at it for awhile now - some of the markings on a camera lens can be downright confusing.

Not only that, but lenses have a ton of markings, so not only are some of them mysterious, but there’s also a lot of them to learn and remember.

In this quick guide, we offer a tutorial on how to read some of the most common markings on your lenses.


Focal Length

The focal length of your lens is the distance between the middle of the lens and its focal point. That means that longer focal lengths (i.e., a 100mm lens) require a longer lens barrel than a shorter focal length (i.e., a 24mm lens).

Some lenses have a fixed focal length, like 50mm or 85mm, while some lenses have a variable focal length, like 24-70mm or 70-200mm.

These focal lengths are marked on the top of the lens barrel. As you can see above, this lens is a 50mm.

On a zoom lens, you’ll also find various focal lengths indicated on the zoom ring. As you rotate the zoom ring a line (usually printed in red) will align with a focal length to tell you the length at which you’re shooting.


Distance Scale and Focus Range



Some lenses have a window on the barrel of the lens that indicate focus range and distance, as seen on the lens above, bottom right.

The distance scale offers measurements in feet and meters, and gives you an indication of the lens’s minimum focusing distance, or how close you can get to a subject and have it still be in sharp focus.

In some cases, these markings will not appear in a window as seen above, but will be printed directly onto the barrel of the lens. In either case, they serve the same function to tell you how closely you can get to a subject and still get a focused shot.


Maximum Aperture

Different lenses have different maximum apertures.

Typically, the maximum aperture is denoted at a ratio, like the 1:4 marking as shown in the image above.

What this indicates is that this lens has a maximum aperture of f/4. Since this is the only number present, it also means that this lens has a constant aperture of f/4. That is, no matter the focal length being used within this lens’s 24-105mm focal range, the lens will always operate at f/4.

This lens, however, has different maximum apertures for different focal lengths.

As you can see printed on the end of the lens, the maximum apertures range from f/3.5-f/5.6, where f/3.5 is the maximum achievable aperture at an 18mm focal length and f/5.6 is the maximum achievable aperture at 55mm.


Aperture Ring

On older lenses, you’ll also find an aperture ring. In the image above, the aperture ring is located on the near side of the barrel, and ranges from 2.8 to 4 to 5.6 and so forth.

The aperture ring was used in the days of film on manual focus lenses to set the aperture of the lens.

As you can see above, the ring indicates various apertures at which the lens can operate.

These aperture rings are seldom found on modern lenses because digital cameras - not the lens - are responsible for determining the aperture that’s used.


Filter Size

Also on the end of the lens is an indication of the diameter of the lens, which is measured in millimeters. In this case, the diameter of this lens is 77mm.

This also indicates the size of filter that the lens requires. This is essential information to have when buying a lens filter as there are a wide range of sizes of lenses.

You can use this outline to learn what these markings mean, and use this knowledge to more effectively utilize your lenses.