Part Five – Introducing the Aperture
In this video we talk about the first of the 3 controls we introduced you when talking about the exposure triangle. This is all about the “Aperture” and we discuss the F-stops and their relationship to each other.
Transcript of Video
““We’ve talked about the exposure triangle as having the 3 controls we need to pay attention to and learn to master so that we are getting better exposed photographs we’ll look at the first of these controls which is the Aperture.
The Aperture is not actually built into the camera, it’s built into the lens. And effectively what the Aperture does is allow you let more or less light into the camera thus increasing or decreasing your exposure.
And effectively the Aperture is a hole in your lens. If you look at this illustration it shows you what is happening when you change your aperture settings.
If you have a “full aperture” then it’s a bigger hole effectively which is allowing more light into the camera and as you stop down your Aperture, and “stop down” just means making the hole smaller, then as it gets smaller you’re allowing less light into the camera.
So without getting too technical as you change your aperture settings you are either making the hole bigger or smaller. If the holes bigger it’s letting more light into the camera, if the holes smaller it’s letting less light into the camera.
The Aperture settings as you can see on this illustration are called F numbers and these are designed to allow you to know what size of hole you have in the lens.
As you can see the smaller the number the larger the hole which initially appears counterintuitive. But when you realise the numbers are based on fractions then it makes more sense.
The illustration shows full stops (many modern day cameras have further incremental settings in between these which are partial stops which we’ll ignore for the time being).
Try to remember the full stops for now these are the most important, partial stops are just for fine tuning
But as you stop down from one full stop to the next for instance from f1.4 to f2 the hole becomes 1/2 the size so letting half the amount of light in to the camera.
We are moving from left to right as we look at the illustration.
As you move from f2 to f2.8 you’re letting half the amount of light in again and as you move from f2.8-f4 you are letting half the amount of light in again and so on.
Obviously when you move in the opposite direction from say f11 to f8 you are letting twice as much light in from f8 to f5,6 your letting in twice as much light in.
You’re coming in the opposite direction from right to left as we look at the illustration.
It’s important to remember as we move from each of the full stops to the next we are either halving or doubling the amount of light to the previous one depending if you are moving in the left direction or right direction in this illustration because that’s going to help you balance the other exposure controls which we will be discussing in other videos.
If over time you can memorise these “full stops” it will help you to be less dependent on your camera, you will be able to know what f stop is next in the sequence.. f1.4, f2, f2.8, f4, f5.6, f.8, f11, f16, f22 f32. Most lenses that come as part of camera kits range from f4-f32 only when you move up to higher spec lens will you encounter f1.4, f2, f2.8 apertures. So initially concentrate in memorising the apertures that are present in your lens.
You do have to be careful with some zoom lenses because they have moving maximum apertures so has you zoom in and out the maximum aperture moves depending if you are zoomed in or not from say f4-f5.6 so be wary of this when setting your aperture wide open.
As well as using your aperture to control exposure it can be used for creative purposes. And particularly with regard to depth of field.
Looking at the illustration on screen if you have your aperture wide open then you get a shallower depth of field. And depth of field is how much of the image is in focus from front to back.
So if you have a shallow depth of field then you have less in focus from front to back so if you’re photographing a portrait of someone and you want a blurry background then you want a shallow depth of field to achieve that.
If you’re photographing a landscape you’ll want most of the landscape from front to back in focus so you’ll want a deeper depth of field and you’ll want to be on the right side of this illustration in the f11 – f64 range”.