What Does The MM Mean On A Camera Lens?


Are you a newbie seeking to take up photography as a hobby? Or perhaps, you have enrolled yourself in a photography course to learn it professionally? Regardless of your reason to learn photography, you might be overwhelmed by the sheer amount of technical terminology involved in this field.

There is no shame in not knowing what you’re doing. However, even as a beginner, you would probably know that the lens is the workbench of a camera. When I was shopping for camera lenses, I was shocked by the complicated combination of lens numbers and lens symbols written beside the lens model.

FL MM- mm mean on a camera lens

I did not know how to read camera lens specifications at that time, so it was just a jumbled mess to me. But don’t worry, we’re together in this.

There are so many things you need to keep in mind when you are buying a new lens. What is an aperture? What is a focal length? But most importantly, what does mm mean in lenses? You will often see lens numbers like “120mm” “35mm” written on the lens barrel.

So what do the numbers on a camera lens mean? The “mm” is the ‘focal length’ of the camera, measured in millimeters. To all the math-phobic people reading this, please don’t run away just yet. Reading mm specifications is not as difficult as it sounds.

In this guide, I will help you understand what mm means in photography, what lens size means, and how to read camera lens specifications, along with a camera lens mm comparison.


As discussed before, I pointed out that “mm” is the focal length in millimetres. So before delving into the discussion of what does mm mean in lenses, we must first understand what focal length is.

I am not going to discuss complicated physics here, but I will explain how it works. Focal length is the essential element in any lens.

It is not the literal length of the lens but the measurement of the distance between the camera’s sensor and the optical center. You can determine a camera’s focal length by focusing it to infinity. I guess you might be confused about what “optical center” is, right?

Well, the lens of a camera does not comprise a single glass. Instead, it is a layering of different lens elements and groups of features.

The optical center is the point where light rays come together to converge and form a sharp image. But what does focal length or the mm lens meaning signify in practical life? The answer lies in what the focal length tells, some of which are as follows:

focal length - mm mean on a camera lens
  • How much of the scene the lens can capture
  • How large your subjects appear within the frame
  • The distance you need to maintain between the subject and yourself to get a clear shot.

One major confusion for Americans is the use of “mm” as measurement. This is probably because the millimeter lens belongs to the metric system. Basically, 1 mm is 0.03937 inches. The focal length might or might not be printed with an “mm” all the time. Sometimes lens numbers and lens ratios can also be represented in different formats. Some of them are given below:

  • X-Y mm f/A-B (e.g 35-200 mm f/1.8-2.5)
  • X-Y mm f/A (e.g., 35-200mm f/1.8)
  • X mm f/A (e,g 35mm, f/1.8)

I still don’t understand what does mm mean in lenses? No worries. Just remember that the higher the mm in lenses, the bigger is the zooming capacity. A lower number of mm in lenses means that you can use the lens for wider shots.

All of these seem relatively simple until you get to know that you have different types of focal lengths along with different mm measurements. We’ll cover these in the following sections. 


By now, you must have understood what does mm mean in lenses. This section shows camera lens mm explained and explores what do different mm lenses do. So before we explore how to read camera lens specifications and have a lens zoom comparison, we should first try to understand that different mm lenses exist and the usage of the lenses change accordingly.

Firstly, mm in lenses is the viewing angle which is dependent on the sensor size and focal length. Lenses can be either prime or zoom. Prime lenses denote a fixed amount of magnification, while a zoom lens is capable of adjusting magnification.

With that in mind, let’s proceed with the different mm lenses:

Normal/Standard Lens

Out of all the different mm lenses, the standard or normal focal length is known to be almost equal to the diagonal of the negative image. A normal/standard lens closely resembles the human eye in terms of viewing angle. They are usually around 50mm.

So what does 50mm mean? This is kind of mm in photography is very useful and convenient because the picture looks natural. The 50mm is a prime lens which is sometimes also known as “nifty-fifty” because it is usually lighter, faster and usually comes with a wide aperture. But is 50mm wide angle?

This is a common mistake where many newbies make. The 50mm lens has no distortions at all and represents the replica of how a human eye sees the world.

Telephoto Lens

Telephoto lenses are largely misunderstood and often confused with standard zoom lenses. This is mostly because beginners don’t understand mm lens meaning and don’t know how to make lens zoom comparisons. Let’s clear out the confusion. In standard zoom lenses, the apparent magnification of the lens can be adjusted. However, telephoto lenses simply mean that they have a narrow field of view.

Telephoto lenses usually range approximately 70-200mm. So what does the mm mean on a lens? Well, it means that with such a lens, you get the power to compress a distant subject into the frame and have the ability to isolate specific objects into the periphery of your camera lens.

telephoto lens

Is this too complicated to understand? Let me reframe my words more simply. Basically, a telephoto lens can bring your subject and background closer to each other. For instance, if you wanted to take pictures of a lion or tiger, you wouldn’t want to approach dangerously close to them, right?

In that case, a telephoto lens will help you bring this lion or tiger to an extremely close point in your vision. Viewing through a zoom lens feels as if you traveled all the way to your point of focus!

Super-Telephoto Lens

Now you are probably scratching your head, thinking, “There’s a telephoto lens and a super-telephoto lens as well?”. Well yes. Think of it as a telephoto lens but make it twice as amazing! A super-telephoto lens pushes the limits of a typical telephoto lens.

These lenses usually range between 300mm focal length and extend up to 600mm. Sometimes, the focal length can extend way beyond 600mm. For understanding what does the mm mean on a lens, we should look at how telephoto lenses work. Have you watched wildlife documentaries on National Geography? Did you ever notice how closely the camera is viewing the animals?

For example, sometimes, you will be able to see the close-up of a crocodile’s teeth or close-ups of lions feasting on their kill. Do you think the cameraperson casually walks up to them to take those dangerous shots? That is quite unlikely. This is where super-telephoto lenses work their magic.

These lenses are equipped with cutting-edge technology, usually with excellent image stabilization. This allows you to capture images from miles away. One drawback of these lenses is that it is usually very heavy, so you always need to carry a tripod and a special grip attachment to mount these lenses. 

Wide Angle Lens

As a rule of thumb, any mm in lenses having a focal length of less than 50mm is a wide-angle lens. Usually, you will find wide-angle lenses with a focal length of 35mm or below. This type of lenses does the exact opposite of what a telephoto lens does. Instead of isolating specific subjects into the frame, these lenses fit in as much as visual elements possible into the frame without distorting the image.

While a telephoto lens brings the background and the foreground close to each other, the wide-angle lens emphasizes the difference between the foreground and the background size. To give you a clearer description, let us take a scenario where you are visiting the sea beach. Now, the whole wide sea is extremely vast, right? With a telephoto or a standard zoom lens, you won’t be able to fit the entire horizon into the frame.

However, upon using the wide-angle lens, you will be able to take an amazing shot of the entire stretch of the sea! This is because the wide-angle lens stretches your viewing angle. But then what does 35mm lens mean? You see, most wide-angle lenses cause slight distortions in the viewing angle.

This becomes apparent when you are taking portraits or pictures of architecture. The 35mm, however offers you a slightly wider than normal angle of view while keeping distortion at a minimum. It is neither too short nor too long and gives you a unique picture while keeping a natural look. 

The most versatile wide-angle range, however is 18-55mm. But what does 18 55mm lens mean? Firstly, the 18-55mm is a wide-angle zoom lens that comes as a part of the camera kit. This is a very underrated lens since you can usually get it free of cost. However, it provides a wide range of opportunities for photographers.

At 18mm, this is a pretty great wide-angle lens, suitable for landscapes. In the middle range, around 35mm, it works as a good travel lens, and at 55mm, it works as a short-telephoto zoom lens. This three-in-one capability makes it one of the essential beginner-level lenses.

5. Ultra-Wide Angle/Fisheye Lens

These lenses help in achieving an extremely wide angle of view. It usually has focal ranges between 4.5mm to 16mm. Usually, you will find ultra-wide lenses in three forms- cropped circle, circular and full-frame. A cropped circle lens will give you images with slightly curved edges, and a circular lens will give an almost spherical image.

On the other hand, the full-frame type will create a rectangular crop of the circular image. The camera lens mm meaning lies its usage. This is not a general lens and is used only in few photography niches where you are required to fit almost every element of the environment into the lens frame.

For instance, when you are taking aerial shots of a mountain range, you would want to capture as much as possible. This is where an ultra-wide-angle lens would come in handy. 

6. Macro Lens

Macro lenses are used for extreme close-ups. They can range from around 50-200mm. These types of lenses won’t help you click distant subjects as they lose out focus, but when it will help you bring the subject to an extremely close point of focus. So these are like telephoto lenses but with a close near point. They can be used for getting larger or life sizes of small subjects like insects and small flowers.

So these were some of the different types of lenses, each with different advantages. But understanding lens mm without understanding the camera mm difference between them would not be a practical approach. Thank for reading our article!


Focal Length

Type of Lens

Used in

4.5 mm-16 mm

Ultra-Wide Angle/Fisheye

Extreme sports, Landscapes, Panorama

14 mm-35 mm

Wide Angle

Architecture, Landscapes

35 mm-85 mm


Street, Documentary

70 mm-200 mm


Portrait, Wildlife, Landscape

300 mm+


Birds, Wildlife, Sports, Astrophotography

50 mm-200 mm


Product, Food, Macro Wildlife

Here is a comparison chart explaining what does mm mean in camera lenses. The guide here shows different focal lengths along with what they are called. This chart also shows what these focal lengths are used for -

  1. 1
    Ultra-wide lenses are called fisheye for a reason. So what does what does lens mm mean when it comes to ultra-wide lenses? What they do is give you a wide panoramic image that looks hemispherical. This happens due to the strong barrel distortion produced by the lens.

    With this kind of lens, you can easily click pictures which under normal circumstances, would be impossible. It is great for extreme sports photography such as when taking pictures of people jumping on skateboards or bikes. You can also take amazing panoramic shots from a high rooftop of the entire city below.
  2. 2
    Wide-angle lenses are perfect when the foreground objects are prominent. These kinds of lenses are suitable for close spaces like caves, cars, small rooms, etc. They are great for taking pictures of large architectures and large nature elements like giant trees or mountains.
  3. 3
    Standard lenses are very versatile and can be used as everyday lenses. They are mostly used for street photography and documentaries. They have a viewing angle that is almost the same as the human eye so if you want to take candid shots of everyday life, this is a suitable lens for you.
  4. 4
    A telephoto lens is typically used for wildlife and landscape photography. These lenses help in magnifying everything in the frame. And since you are taking pictures from such a faraway distance, you can easily snap pictures of unsuspecting subjects who might be easily startled (such as birds, small animals like squirrels) or might be too dangerous to approach (like a lion or crocodile). 

    It is great for portraits as well since you would be able to take candids easily of people who might otherwise get overwhelmed and self-conscious with the presence of a camera.
  5. 5
    A super-telephoto lens pushes beyond the focal length of a telephoto lens. So what does mm mean in camera lenses when using super-telephoto equipment? With this, you can easily take pictures of sports since you will be able to isolate each player in the frame.

    Moreover, the super-telephoto lens can be used for the usual types of photography like wildlife. But the super-telephoto lens shines mostly in astrophotography. Using this lens, you can get clear shots of different celestial bodies.
  6. 6
    Macro lenses can be used for taking extremely detailed pictures of everyday objects. They are suitable for taking pictures of food and products because the lens ratio of this type of focal length is 1:1 or higher. It is great for taking pictures of detailed surfaces like flowers and fruits since it will help to bring out the vividness of the textures.


Just when you thought you understood what does mm mean for lenses, the next confusion appears. Now the problem is, how to read camera lens specifications?

Merely knowing what is the mm on a lens and the different types of lenses helps to a certain extent but you have to understand that focal length is not the only thing you need to think about while reading camera lens specifications. In this section, I will guide you through the other confusing symbols and letters other than the usual camera lens mm meaning.


When you are looking at a lens body, you will see terms like “f/1.8” or “f/1.8-2.8”. So what do the numbers on a camera lens mean? This is the aperture of a lens. Aperture refers to how wide a lens can open to let in more light. The lower the f-number, the more light will come in.

You might have understood what is mm in dslr lens, but this is a very important aspect as well. The aperture determines how bright your image will look. Hence, buying a camera with a low aperture is your best bet if you want to click pictures in low light.


This is fairly simple to understand. It is a toggle switch used for switching between manual focus and autofocus. 

IS and VR

This refers to image stabilization and vibration reduction respectively. This is a technology used for reducing camera shake and blurring in pictures. 

Ø Numbers

This symbol refers to the diameter. Even this is measured in millimeters. So what does mm in lens mean in this case? It simply refers to the diameter of your camera lens. So if you see something like Ø62 written around the lens, it means that the diameter is 62mm. This is important to know when you are buying a lens filter or cap. 


I hope this article helped you in understanding what does mm mean on lens. Different lens manufacturers have different ways of labeling their lenses. However, at the most, you will find the focal length and aperture being labeled on the lens. You don’t need to be a camera expert to read lens specifications.

If you keep in mind the basic meaning of the symbols and numbers, you can easily choose the best lens for yourself. 


I'm Xavier. I am a professional writer and blogger. It all started when I fell in love with my camera, which was presented to me when I was ten as a birthday gift. Since then, I wanted to become a cinematographer and also succeeded in that. So I am here researching and reviewing the filmmaking gadgets and giving out my top gadgets from the market.I hope you find my review articles interesting and helpful.

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