Shooting modes
All these aperture and shutter combinations have produced the same exposure for this picture. If either element of the combinations were to be changed the image would be brighter or darker.
1/250 second atf/4
1/125 second at f/5.6
1/60 second at f/8
1/30 second at f/11
1/15 second at f/16
The aperture and shutter function in relationship to each other, because in order to maintain what you or your meter calculate to be accurate exposure, both the volume of light entering through the aperture and the length of time the film or sensor is exposed to that light must be adjusted. If you increase the volume of light by enlarging the aperture, to maintain the same exposure you have to shorten the shutter speed.
Exposure meters
The exposure is calculated by your DSLR or SLR camera’s built-in exposure meter. When you compose a picture in your viewfinder, the meter analyses the light reflected off the subject and calculates what it considers to be a correct exposure of that subject.
When you are using the P, S and A modes at least part of the exposure is automatically made by the camera. In the case of M (manual), you have to set both the aperture and shutter yourself. Whether or not your photograph will be correctly exposed at the settings you have chosen is shown in the display in the viewfinder’s control panel so that you can adjust them if need be.
Although built-in meters in good-quality cameras are now very efficient, some photographers still prefer to use a separate handheld exposure meter. These use two methods of analysing the light and making exposure readings: like the camera’s meter, they measure the light reflecting off the subject, or they can measure the light falling on it, which is called an incident light reading.
When you are working with the exposure in M (manual) mode the exposure display in the control panel of the viewfinder shows if your picture is correctly exposed and, if not, whether you need to allow more or less light.
Quick tip
• Your camera’s exposure reading is only a guide to what is deemed correct. As you become more experienced you will want to adjust the reading to suit your own interpretation of the picture.
Handheld incident meters are used to take readings when studio flash units are providing the lighting. Handheld spot meters, which measure the light on a small area, are seldom used by the DSLR or SLR user now because most camera meters offer that facility.
Meter modes
Exposure compensation
Auto exposure lock
Self timer
Meter modes
Most cameras provide you with three exposure modes which evaluate the light reflecting off different areas of the picture.
Matrix mode (Nikon) or evaluative metering (Canon) averages the exposure over the whole viewfinder frame. It is recommended by camera manufacturers for all-round situations but does not work well with exposure compensation or on exposure lock.
Centre-weighted mode meters the whole frame but makes the centre of the frame (as marked in your viewfinder) the most critical. It is ideal for portraits and is also recommended when using strong filtration.
Spot meter mode (Nikon) or partial metering (Canon) takes a reading off a small centre circle (only about 2 per cent of the frame). It is ideal if you have a small but critical area in your frame that you want to be sure is well exposed. This is often much brighter or darker than the rest of the picture, but you can spot meter it and let the rest of the frame take care of itself.
Exposure compensation
When you are shooting in P, S or A modes the camera automatically calculates the exposure. If you want to override its reading, use exposure compensation. By pressing the button and rotating the control wheel you have a choice of making the pictures brighter or darker (shown on the camera as + or – respectively).
This can be useful when you have a light subject in front of a dark background, for instance, when you may need to give less exposure than the camera has calculated because it is trying to record detail in the dark background and will make your lighter subject in the foreground too bright. Conversely, if you have a dark subject in front of a bright background you may want to give more exposure.
Auto exposure lock (AE AF)
If your subject is off-centre in the viewfinder the exposure could be incorrect. The answer is to select centre-weighted or spot metering, put the subject in the centre of the viewfinder and hold the shutter button halfway down to set the focus and exposure. Use the auto exposure lock, recompose your picture and take the photograph.
Self timer
The self timer delays the shutter release, giving you time to push the button then run around to include yourself in the shot. If you don’t have a cable release or remote control to fire the camera on long exposures, use the self timer to avoid camera shake.
Quick tip
Taking several shots of the subject at different exposures each side of normal exposure (bracketing) ensures that one will be correct. Some cameras can be set to do this automatically. You can select the number of steps you want to bracket. Keep shooting until the number of brackets you selected is finished.
Flash
Having flash at your disposal can be invaluable on many occasions, and modern automatic systems make