You love photography, right? You snap lots of life’s memories to cherish, enjoy and share with friends and family but how do you ensure you’re capturing the ‘type’ of photos you want? Thankfully, photography is subjective and very personal – one type of shot will work for certain situations (or people) but not in others, which is great… but also tricky!
Things to consider before we start
The camera is merely a box that you let light into. The light travels down the lens, passes a shutter (more on that below) and hits a digital sensor that records an image.
Aperture (Av): The is the size of a hole (usually at the back of the lens), that allows light into the lens to hit the sensor. We measure the Aperture in f-stops. Take a look at this info-graph.
The smaller the f-number, the wider the hole – (yes it seems a little backwards) – so obviously, the wider the hole, the more light entering the lens. This is why your camera will call Aperture ‘Av’ – aperture value.
Aperture also controls the Depth Of Field (DOF)
DOF is essentially how much of the image is in focus. The wider the aperture (smaller f-stop number), the less of a DOF you have. So in the info-graph above, an f-stop of 1.4 means the background will be super blurry. And vice versa for a narrower (i.e. larger f-stop number) aperture.
Shutter Speed (Tv): So aperture controls how much light enters the lens, shutter speed controls how fast that light enters – this is why shutter speed is often known as ‘Time Value’, hence ‘Tv’ printed on your camera dial.
Watch this 20 second video:
This is what’s happening, when the shutter button is pressed, the camera’s mirror lifts up and we can see the first shutter sitting over the lens, that shutter moves, exposing the sensor to however much light is coming into the lens (set by Av), very quickly the second shutter moves across the sensor, stopping any light hitting it.
If we break it down, the action is this:
– Shutter button pressed
– Mirror up
– First shutter moves allowing light to hit the sensor. Pause
– Second shutter chases the first, covering the sensor, blocking light.
When we set the ‘shutter speed’ it is the pause we are controlling.
As you can see from the info-graph, shutter speed (or to be more specific, the pause) can be either super quick (1, one thousandth of a second) or really rather slow (half a second). My camera can actually allow me to make the shutter speed even slower and even faster.
To freeze super quick action, like someone running, without any blur, use a super quick shutter speed like 1/250 or 1/500. To capture something moving fast with blur, for example, a car going fast, use a slower shutter speed like 1/100 or 1/50. When using a slow shutter speed, you’ll want to mount your camera on a tripod.
A side effect is this. Using a fast shutter speed means less light is being allowed to hit the sensor, so you’ll want to compensate this by setting the aperture wider (smaller f-stop number). And when using a slow shutter speed (i.e, the sensor is exposed to light for longer), use a narrower shutter speed (larger f-stop number).
Understanding Av and Tv are the basics of photography. Play about, experiment to find your own style and remember, there are no right or wrong answers.