Controlling Your Exposure
You will often hear photographers talking about “getting the right exposure” or “making an exposure”.
Modern digital cameras are so full of technology that it seems they can make all these decisions for you. I’m sure your new bridge camera can virtually take photos by itself, just your index finger required.
Even a little knowledge of how exposure works, though, can not only improve your results, but also your enjoyment and sense of achievement in your photographic endeavours.
Exposure is an essential element to any photography so what is it exactly?
Exposure determines how much light is allowed through the camera’s lens to the digital sensor and will affect how the final image appears.
There are three distinct elements (sometimes referred to as the ‘exposure triangle’) which contribute to the optimum exposure for a photograph.
1. Aperture- the size of the opening in the camera lens
2. ISO- the sensitivity of a digital camera’s sensor to light
3. Shutter speed- the amount of time that a shutter stays open
The Right Exposure?
Technically there is no such thing as the ‘right’ exposure but there is usually a point that people agree is the best exposure for a particular image. If the sensor on a digital camera does not receive enough light an image is said to be ‘underexposed’ (too dark).
If too much light reaches the sensor the resulting image is ‘overexposed’ (too bright).
The aim with exposure is to find a good balance between these.
When considering correct exposure it is important to remember that each element of the ‘triangle’ (aperture, ISO and shutter speed) will affect the others.
Exposure and Sun tan
Think of exposure like trying to get a perfect tan. Some people just have to be outside and they’re golden brown where as others instantly become lobsters. Skin type could be compared to the ISO rating on a camera-some are more sensitive to the light than others.
In this instance, shutter speed could be likened to the length of time you spend out in the sun. The longer you spend in the sun the increased chances of you getting a tan (although too much time in the sun and you could quickly be ‘overexposed’).
Aperture is like sunscreen. Depending on the strength of the sunscreen, it will block the sun at different rates.
So, even a person with a more sensitive skin type could stay in the sun for longer if they applied a high strength sunscreen. (E.g. decrease the aperture on a camera and you can slow down shutter speed and/or decrease ISO).
While the sun tan illustration is not perfect, it is helpful for understanding exposure value.
This is a number referring to the various combinations of aperture, shutter speed and ISO used to achieve an individual exposure.
Each EV step relates to a one-stop adjustment of the ISO, shutter speed or aperture.