What Is Aperture In Photography?
In photography, when we talk about the aperture, we're referring to the opening in the camera lens through which light passes when you take a photo. The aperture combined with the camera shutter controls the amount of light that reaches the camera sensor when you take a photo.
Okay, I know I'm talking about exposure in general here, but I really should have mentioned that ISO is the other part of the exposure triangle, apologies for that omission (not emission!). ISO is the sensitivity of the sensor to light.
Hi, everybody, welcome to Episode 23 of the photography explained podcast. In this episode, what is aperture in photography?
I'm your host, Rick, and each week I will try to explain one photographic thing to you in plain English in less than 10 minutes without the irrelevant details. My aim is to explain things in just enough detail to help us with our photography and no more.
Now I just noticed a bit of a flaw in my erm, my opening text because I'm doing this twice weekly. So I'm actually explaining two photographic things in plain English in less than 10 minutes without the irrelevant details in a week, not one.
Will I carry on and do that in the new year? Who knows? I was thinking of going to once a week, but I'm not gonna lie to you. I do actually enjoy this.
You can listen to the episode here
Or you can read on - it’s entirely up you!
Right, let's get on.
Okay, so about aperture.
Let's have a look at this in a little bit more detail. Not too much, but enough. So you understand. And as it turns out, so I understand because I got a few things wrong on this one, which was a little bit, well, let's just say that I thought I knew more than I did.
So I had to do some actual work and research on this one. Which is good, because that was always going to be part of the process of the podcast. I can just sit there for 10 minutes and tell you all about this, that and the other. But when I start writing my notes, yes, believe it or not, I do prep these episodes, I find gaps in my knowledge.
So I've enjoyed finding those gaps and filling them and hopefully giving you a complete and correct answer, but just enough.
Okay, then what is the aperture made of?
Obviously, camera lenses are made of all sorts of stuff, polycarbonate plastic, glass for the optics, and metal bits here and there. I told you I didn't want to get too technical. But what is the aperture actually made off?
Now then I have written to Olympus, Canon, and Sony. And you know what? They wouldn't tell me. I'm surprised by that. So I can tell you that they are probably metal. I can't do any more. I can't tell you which metal - I can't say anything more about them.
Seems like it's a bit of a trade secret, which was a bit of a surprise to me. Let’s hope we have a bit more joy with my question to these guys about what's the shutter made of – not holding any hopes, to be honest with you.
The actual aperture
You need to look at a picture of a camera aperture or get your camera and stop down the aperture and you can see it making the hole smaller. That's the important part of this.
If I use, for example, a camera lens, a 50-millimetre F2 lens, F2 is the maximum aperture. F2 is the aperture fully open. So that's as much light as you can get though the camera lens to the sensor.
There is something called an aperture scale.
This is yet another of these things that if we were inventing photography now, we wouldn't have come up with this between us – well I hope we wouldn't.
So what is the aperture scale?
This is a range, I'll give you the range of numbers first, and then I will explain them.
This is the aperture scale in full stops
F1.4, F2, F2.8, F4, F 5.6, F8, F11, F16, F22.
I hope you're still awake. That was dull.
So why these numbers?
Well, if you look into it, there's a number of different explanations for these numbers and to be honest with you, they don't help so I'm going to move on from that. That's not important. But let me tell you something.
This is very important.
Now, you could accuse me of oversimplifying this, but I just want to explain it, so you understand it.
Going with my example of a 50 mm F2 lens, F2 is the small number that is the maximum aperture. So, a smaller number means a larger aperture setting, which means a larger hole, which means more light getting in, and you also get less depth of field.
Now, this is obviously a generalisation, but this is an important principle, larger numbers equals smaller aperture equals a smaller opening. I've actually written this wrong in my notes (but corrected it here)!
So larger number, a smaller opening, less light, and more depth of field.
That's the takeaway. And this is the first time I've used that term.
The smaller number, the larger the aperture, the more light that gets in.
The larger the number, the smaller the aperture, the less light that gets in.
Who came up with this?
No idea. I am sure there is a good reason for this.
What are F stops? Oh, I don't really know, let's not worry about them. If you look on Google, some will say the F stops are apertures. I don't think that's right. Or they say it's the ratio of the focal length and the lens – this could be right. And this is a bit baffling.
Doesn't matter. Larger number, more light, smaller number. less light. That's what matters.
Obviously, there are things like depth of field which I will cover separately.
What are half-stops?
Well, I have helpfully written in my notes here, the bits in the middle. And there are third stops too...
Why can I change the aperture?
Well on a camera, you change the aperture to change the amount of light that gets through to the camera sensor. Now let's assume you haven't changed the ISO (the sensitivity of the sensor). If you wanted to use an example, I'm going to get this wrong - I always do. But let's have a go.
If you had an exposure of 1/500th of a second at F8.
If you wanted to use a faster shutter speed as in 1/1000th of a second, that would be letting half as much light in. So what you do is you change your aperture from F8 to F5.6, which is a full stop. And that will give you the correct exposure with different settings.
So that's one of the important parts of the exposure triangle. So the aperture can be changed.
Now what about an iPhone?
I have not spoken about phones much, but they also have an aperture. Now I'm sure there are clever things that can recreate changing apertures computationally now, which is a lot more advanced and different.
But I currently have an iPhone XS and the aperture on that lens is F 1.8.
Okay, so I think I'm done here. What I wanted to get over, and what I wanted you to understand was the simple principle.
A small number, larger opening, more light
A larger number, smaller opening, less light.
That's the important part of aperture.
Okay, I'm going to stop there. I was in danger of saying something else which would have risked confusing things.
So what's next? Well, the logical next thing which will be in Episode 24 of the Photography Explained podcast is this. What does shutter mean in photography? Let's do this in a logical order.
Thank you
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Yeah, you can also check out my website Rick McEvoy Photography where you can find out all about me. I nearly got through an episode then without getting my words wrong!
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What’s next? In the next Photography Explained Podcast episode 24 - What Does Shutter Mean In Photography?
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