What do the numbers on a camera lens mean?

What do the numbers on a camera lens mean?! // In this post, I break down what the numbers on a lens mean, with focal length explained for beginners, and how to see how any particular lens will perform on your camera. By the end of this video, you’ll know how to read lenses to see what the focal length is, and the maximum aperture!

What do the numbers on a camera lens mean?!

If you’ve been asking yourself that question then you are in the perfect place, as today we’re going to be talking about what all the numbers on your camera lens means, and how you can use this information to decide which lens might be best for you.

So if you've been looking at lenses online, or maybe you already have your lens and you just don't understand what all these numbers actually mean, stick around. as by the end of this post, you'll know exactly what the numbers mean and you'll know how your lens is going to perform!

Psssst! Don’t forget to grab your Which Lens Kickstarter guide underneath the video - it will take the video to a whole new level :-)

Grab your free Which Lens Kickstarter Guide! 👇

The Lens Focal Length Number

So let's start with the first number that you can see on your Lens, which is that big number with the mm after it.

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Now this number refers to the focal length, which is simply how much off the scene you are going to be able to see when you look through the viewfinder. A larger number will give you a telephoto view, which simply means that when you look through the view finder, everything will seem closer to you than it would the naked eye.

A smaller number will means you will have a wide angle lens, which means when you look through the view finder, everything will seem further away.

Now here is an example of that for you. So here is an example of an image taken with a 35mm lens, and then one with an 85 mm lens on the same camera.

What do the numbers on a camera lens mean 35mm
What do the numbers on a camera lens mean 85mm.jpg

So the photographer in the same position for both of these images. One was taken with a 35 and you can see, we can see more in the frame. For the one that was taken with the 85mm, you can see that everything seems more zoomed in, it's pulled closer to the frame.

So that’s focal length explained - but how can we tell just by looking at the focal length number how that lens is going to perform on our camera?

How to tell how a focal length is going to perform!

The thing to remember with regard to focal length is that the 50 mm lens is what is closest to the naked eye.

So if you forget about having a lens there for a moment and you're just looking at a scene, roughly speaking, if you put a 50mm lens onto your full frame camera, it is going to give you roughly the same field of view.Now it's not exact, but it's kind of close enough.

What do the numbers on a camera lens mean 50mm

So any LARGER larger than 50 mm, so for example, 85mm, 135mm, 200mm, they are going to give you a more zoomed in look. The larger the number, the more zoomed in it's going to appear.


On the other hand, if you have a number that is LESS than 50mm, so 35mm, 24mm or 16mm, then that is going to give you a view that is wider than the naked eye.


How this changes if you have a crop frame camera.

Now so far, so kind of easy, but this all of this refers to a full frame camera.

But if you are new to photography, the chances are you're NOT shooting with a full frame camera. You probably have a crop frame camera and that gives a world of difference on to how your lenses are actually going to perform!

That's because you have a different sensor size and it magnifies the scene. So you can take this exact same 85mm lens, but pop that on to a crop frame camera, then it's going to behave differently.

If I took a 35mm lens and popped that onto a crop fame camera, it's going to look more “zoomed in” than it would on a full frame camera.

So how can we decide or see how a lens is going to perform if we have a crop frame camera?

Well, it's very simple!

What you need to do is take the focal length of the lens, and then multiply that by a number. That number is either going to be 1.6 if you use Canon or 1.5 if you use Nikon.

So for example, if you were using a 35mm lens on a crop frame camera, you're going to take 35 - that's the focal length of the lens - and then you're going to multiply that by 1.5 if you use Canon or 1.6 if you use Nikon.

That’ll give you around 52mm, and what you will see then is closer to how the scene would look with the naked eye.

Make sense?!

That 35mm on a crop frame becomes the equivalent of a 50mm lens.

Let's do the same exercise again this time with an 85mm lens.

So let's take that 85mm and we're going to multiply that by 1.6 (let's assume that we have a Canon!) and that's going to give us an equivalent focal length of 136.

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So our 85mm lens on a crop frame camera becomes the equivalent of 135mm . So it's going to seem a lot more zoomed in!

So I do want you to bear that in mind when people are talking about focal length of lenses. If you have a crop frame camera, remember to do that multiplication by 1.5 or 1.6, and that will show you how how that particular lens focal length is going to perform on your camera.

If you want to get an idea of how different focal lengths perform, then be sure to download my FREE which lens kickstarter guide - it has examples of images taken at different focal lenghts, along with a guide about what you might want to use each one for. Go here to download it!

Focal Length and Zoom Lenses

So that was just with one focal length. But you may have a zoom Lens, in which case you're going to have two different numbers separated to by a dash.

16-35mm what do the numbers on a camera lens mean

So this particular lens is a 16 to 35mm. So that means there is a range of focal lens in this one lens.

So when you just have the one number, for example, an 85, it's got one fixed focal length. If you want to get closer or further back, you'd go and have to move your feet! It's fixed at that focal lens.

However your Zoom Lens, because it has that two numbers, means you can move the zoom ring to zoom in and zoom out and you can go through that whole range of focal lengths.

The Maximum Aperture Number.

The next number we are going to look at from the numbers on your lens is the aperture.

what do the numbers on a camera lens mean aperture

Now the aperture number is normally just written along the side or on the rim of your lens, and you'll see that it's got 1: 1.8 on this particular lens, meaning that it has a maximum aperture of F1.8.

Now if I look again on my Zoom Lens, the 16 to 35mm, you can see it's got 1 and then it's got 2.8. So the maximum aperture of this lens is F2.8.

What do the numbers on a camera lens mean? 16-35mm, Aperture F2.8

Now on some lenses you will actually see that you have two aperture numbers, and what that means is that you have a variable aperture lens. You'll normally find that on your zoom lenses.

What that simply means is if you zoom in, you are going to get a different maximum aperture than if you zoomed all the way out.

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(If you’d like to learn more about Aperture and Depth of Field, be sure to read this!)

So here's what I'd like you to do now. Go and grab your lens (or have a look at the one online if you haven't got one yet) and in the comments below, let me know what the focal length is.

And if you're using a crop frame camera, tell me what the equivalent focal length is and let me know what your maximum aperture is - It's a great little exercise just to make sure that you understand everything we’ve spoken about today!

Now I've actually got an extra little freebie for you that I think you'll love and will totally help to put all of this into perspective of how each lens will perform and what it can be used for. It’s my FREE Which Lens Kickstarter guide, and in that you'll get loads of image examples using different focal lengths so you can see what each one brings to the table. Plus you'll get some suggestions on which best lenses or focal lens you can use for different types of shots! Totally free and totally worth it. Go here to grab your copy!

That’s it from me today, I hope that this answered your question about what all the numbers on a camera lens actually mean, and how you can use this information to see which lens is right for you!