Intermediate Tutorial 2
Getting to grips with the Aperture setting on your camera will open up a new area of creativity in your photography – employing different ‘depth of field’ effects. Learn how Aperture relates to Shutter Speed and focus, and learn about magazine-style portrait photography.
Understanding Aperture – what is Aperture?
In photography, ‘Aperture’ refers to a mechanism within the lens that is controlled to vary how much light passes through it. Changes in Aperture along with changes in Shutter Speed are used to vary the level of light that forms the exposure on the sensor. The lens Aperture is sometimes called the iris because it functions like the iris in an eye – the coloured part round the pupil, which similarly changes size to control the amount of light that enters through the pupil.
In a camera lens, the iris consists of a number (5-8) of small blades that, when drawn apart, create an almost circular opening (like a dilated pupil) – allowing light through. When the blades draw together the opening is reduced which, in turn, reduces the amount of light getting through – as shown right.
Because the Aperture is variable, it is important to know at what position it is set. Each position is given an ‘f value’ or ‘f number’ relating to the diameter of the hole and the amount of light that can pass through.
For example a lens may go from f1.2 (the widest Aperture; maximum light) to f22 (narrowest; minimum light) – in the following series: f1.2, f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, f22.
Values in the series are called ‘f stops’ and each f stop reduces the light level by half that of the previous one. The greater the f number, the smaller the Aperture.
This uniform way of controlling the light level directly, along with a range of Shutter Speed values, enables photographers to control exposure and take creative control. So, let’s say you’re shooting with Aperture f8 and the image is correctly exposed at 1/125th sec Shutter Speed.
You then choose to shoot the same subject at f2 (a change of 4 stops) – this means you also need to change the Shutter Speed to 1/2,000th sec to keep the same exposure.
This is because in going from a medium Aperture to wide, admitting more light, you must change to a faster Shutter to compensate – reducing the light reaching the sensor back to the correct level.
The table below shows Aperture vs. Shutter Speed for the same brightness level of the subject throughout:
All lenses display (usually on the front) their maximum Aperture f number as a guide to their brightness, sometimes referred to as the lens’ ‘speed’. The f value can also be an indicator of the quality of the lens (the lower the f value the better the lens).
A ‘bright’ lens, one with a wide Aperture like f2 or f1.4, allows a lot of light through, meaning faster Shutter Speeds can be used; hence it is also known as a ‘fast’ lens.
Incidentally, a lens’ minimum Aperture is given in its spec, but generally not displayed on the lens.
Aperture effect on depth of field
The size of Aperture has a direct effect on the depth of field (DoF), which is how much of the image is in focus, in front of and behind the focus point. A wide Aperture creates a shallow DoF/range of focus, whereas a narrow Aperture creates a deep DoF.
The first of these images was taken with a wide-open Aperture for a very shallow DoF. The point of focus was set to the model’s face, so only she is sharp – the rest of the image is out of focus.
In the second image, a narrow Aperture gives a deep DoF – the point of focus is the same, but both she and the background are in focus. So you can see how careful use of the Aperture and choosing the right lens has a creative effect on your photographs.
Shallow DoF photography is popular for portrait and magazine fashion shots, as it ensures the subject stands out from their surroundings.
The wider the Aperture capability of a lens, the more dramatic the ‘out of focus background’ effect becomes. Unfortunately, fast/bright lenses with f numbers lower than, say, f2.8 are very difficult to manufacture – and this is reflected in their price!
Telephoto lenses, especially, are intricate and difficult to achieve a good f number due to the large number of components, and require extreme precision. Those huge telephotos you see wielded by sports photographers feature extremely fast ratings in order to achieve the highest Shutter Speeds; professionals will pay as much as £10,000 for lenses of the highest spec.
How to easily control the Aperture setting
Want to experiment with Aperture, but not yet confident enough for full manual?
Look for the semi-automatic ‘Aperture Priority’, found on advanced cameras’ mode dial in the ‘PASM’ settings, sometimes called ‘Aperture Value’ or Av mode, or just shown as ‘A’.
With this setting, the camera allows you to choose your preferred f stop, then automatically selects the correct exposure by adjusting Shutter Speed and light sensitivity (ISO).
It is useful to note what Shutter Speed and ISO your camera chooses, as you work towards full manual control.
LUMIX G models display this on-screen guide whenever you change Aperture settings.
The LUMIX Advantage
LUMIX G models include a very easy way to experiment with Aperture and Depth of Field. The Intelligent Auto feature offers a slider control on the touch-screen, changing focus from deep to shallow – and showing the effect on-screen before you take the shot. We will be looking at creatively using focus/blur effects in the next module.
Practice makes perfect, as they say, and portrait photography is great for trying out wide Aperture.
If it is not convenient to use a partner or friend while you take your time getting used to the settings, simply find a prominent feature of your garden or local park. In Aperture Priority mode, take shots with the Aperture at its widest (lowest F number) and its narrowest (highest) – notice the difference it makes to the Depth of Field, as shown below.
Also try changing the distance between the lens and subject. A wide-angle lens will give you a blurrier background if you get close; telephoto will let you shoot further away yet still blur the background for a short DoF effect.
Not sure what something means? Read our glossary