So here goes, the first of the getting it right series. I am going to discuss the theory and the practicalities of exposure, but firstly let me define what exposure means photographically. When I talk about exposure, I am talking about the amount of light that is enabled to fall onto photosensitive medium such as film (yes, some photographers still use it) or a digital sensor as found in digital cameras. Without getting too technical, Exposure is measured in Lux seconds and generally refers to a single shutter release. So, what that means is how much light was enabled to fall onto a photographic medium in one shot. Simple right, well, there are a few variables. The first is Shutter Speed, second is Aperture and then thirdly ISO settings. There are other variables to take into consideration, but thse are the key controls that you need to be aware of to make sure that you get the correct exposure. This brings me to my next point, what is correct exposure. Well, in my opinion, correct exposure is what the photographer determines correct exposure to be. Sounds vague right, well, what I am saying is this..sometimes a scene can be perfectly exposed but not have any “punch” or drama. So the photographer might decide to underexpose or overexpose the scene. This can have a dramatic effect on the final image. Take a look at the examples below:
Both photos are of babies, yet both have a very different feel. One is very light and bright, almost no dark shadows are visible, the second is very dark and dramatic, almost no light. These effects are achieved by understanding how exposure works, in both cases the photographer did this on purpose to bring across a particular effect. The bright image (high key) is a more soothing image, it is more friendly, the darker image (low key) is more ominous and dramatic, there is more “feel” in the image. So, how did the photographer achieve this. The photographer told the camera how to expose for these images by using his camera’s lightmeter. If you have an SLR camera, when you look through the viewfinder, with your camera on manual (more about this later) you should see a lightmeter scale, similar to this.
You will see this when your camera is on Manual mode. That means that you are controlling the light. Normally the scale will be from -2 to +2. The middle point (as shown) will indicate correct exposure. So what has to happen is, you as the photographer need to adjust your Aperture and shutter speed to get the indicator to the middle to ensure correct exposure. If you want a High key image (bright) the allow more light to fall onto the sensor so adjust the settings until the indicator is on the + side. If you want to underexpose then adjsut the settings until the indicator is more on the – side. Its really that simple. The important thing here is to experiment and take a few shots, see what works. Now that we have brief understanding of what exposure is, THE NEXT TIP will be on the relationship between aperture and shutter speed…until then, experiment.