What do the numbers on a camera lens mean?

So in this video we are going to be
talking about these, and specifically what do the numbers on a camera lens mean. 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,
then stick around because this is the perfect video for you! By the end of
this you’ll know exactly what the numbers mea, and you’ll know how your
lens is going to perform. So let’s start with the first number
that you can see on your lens which is the kind of big number with the mm after
it. Now this number refers to the focal length, which simply put, is just how
much off the scene you are going to be able to see when you look through the
viewfinder. So a larger number will give you a telephoto view, which simply means
that when you look through the viewfinder everything will seem closer
to than the naked eye. if you have a wide-angle lens that means when you look through the viewfinder everything will seem further away. Now here is an example of that for you. So here is a 35 mm lens, and here is an 85
mm lens on the same camera. So you’re sitting in the same position for
both of these images – one was taken with a 35 and you can see that you can see
more in the frame. And one was taken with the 85 and with that you can see that
everything seems more zoomed in, its pulled closer to the frame. So how can we tell just by looking at the focal length number how that lens is going to perform
on our camera? So what the thing to kind of remember is that a 50 mm lens
is what is closest to the naked eye. So if you forget about a lens for a moment
and you’re just looking at a scene, roughly speaking if you put a 50
mm 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. So
any number larger than 50 mm so, 85, 135, 200 mm, they are going to
give you a more zoomed in look. So that 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
50 mms – so 35 mm, 24 mm, 16 mm, then that is
going to give you a view that is wider than the naked eye. Now so far so kind of
easy, but this all refers to a full-frame camera. Now if you are new to photography the chances are you’re not shooting with a full-frame camera, you have a crop
frame camera, and that gives a world of difference onto how your lenses are
actually going to perform. That’s because you have a different sensor size, and it
tends to magnify. So you can take this exact same 85mm lens, and if you
pop that on to a crop frame camera, then it’s going to behave differently – it’s
actually going to look more zoomed in. It’s exactly the same if I take a 35mm lens and pop that onto a crop frame camera, it’s gonna look more zoomed in than it would in a full-frame. So how can we decide, or see, how 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 and then multiply that by a number. Now
that’s 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, and that will
give you around 52. And what you will see then is closer to how the scene would
look with a naked eye. So that 35 mm becomes the equivalent of a
50 mm. Let’s do the same exercise again, this time with an 85mm
lens. So let’s take that 85 mm 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 a 136mm. So our 85mm lens on a cropped
frame camera becomes the equivalent of 135 mm, so it’s going to seem a
lot more zoomed in. So I do want you to 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 that lens is going
to perform on your camera. So that was just with one focal length, you may have
one of these, which is a zoom lens. In which case you’re going to have two
different numbers separated by a dash. So this particular lens is a 16 to 35
mm, so that means there is a range of focal lengths in this one lens.
So when you just have the one number like we have here, which is 85, it’s got
one fixed focal length. If you want to get closer or farther back you’re going
to have to move your feet – it’s fixed at that focal length. Our 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 next area we are going to look at for the numbers on your lens is the
aperture. Now the aperture number is normally just written along the side
here 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 I have here,
16 to 35 mm, you can see it’s got 1e and then it’s got 2.8, so the
maximum aperture of this lens is F 2.8. 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, and you’ll normally find that on your zoom lenses.
And what that simply means is if you zoom in you are going to get a different
maximum aperture then if you were zoomed all the way out. So here’s what I’d like
you to do now: go and grab your lens, or have a look at one on line 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 understood everything in this video. Now
I’ve actually got an extra little freebie for you that I think you’ll love.
You can go and download my “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 lengths you can use for different types of shots. So you can grab that – the
link is below in the description. Now as always if you enjoyed this video please
give it a thumbs up, hit that like button below, and be sure to subscribe. There are new videos every single week, so to make sure you are the first to know when the
next video comes out, hit that red subscribe button, and then
little notification bell that pops up just after it. As always thank you so
much for watching, and for being here, and I will see you soon!

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