All cameras have a shutter mechanism to expose the sensor for exactly the right amount of time. The shutter opens to begin the exposure and then closes again to end it. Most cameras have mechanical shutters, though you can also get electronic shutters, which we’ll come to a little later. Mechanical shutters come in two […]
Shutter speed
The length of time the shutter is open during the exposure and usually quoted as fractions of a second. Each shutter speed is half as long as the one before, for example 1/30sec vs 1/60sec. This exposure ‘halving’ is the basis for balancing up lens aperture and ISO settings. A few cameras have external shutter speed dials but most simply display the shutter speed on the LCD display – you turn a control dial to change the speed.
Lens aperture and how it works
Lens aperture is one of the key tools for photographers for adjusting the exposure and for achieving specific creative depth of field effects. The lens aperture is an adjustable hole created by a diaphragm within the camera lens. When you change the size of this hole, you change the amount of light allowed to pass […]
ISO (sensitivity) and how it works
ISO is the unit used to measure and adjust the camera sensor’s sensitivity to light. With film, the ISO setting (or film ‘speed’) is part of the film’s physical and chemical properties and can’t be changed. With digital cameras it’s possible to ‘turn up the volume’ on the sensor to make it more sensitivity to […]
Flash photography basics
Sometimes the ambient light level is too low for successful for photography, or it’s the ‘wrong’ kind of light. This is where photographers turn to flash (or ‘strobe’, if you’re in the US). Flash works by emitting a very short, very powerful burst of light. Energy is stored in a capacitor in the flash head […]
Camera shake and how to avoid it
Camera shake is blur caused by camera movement during the exposure. It happens with indoor shots or outdoor shots in poor lighting or at night, when the low light levels mean the camera uses a longer exposure and hence a slower shutter speed. The slower the shutter speed, the more likely it is the camera […]
Exposure and how it works
Exposure is all about making sure the sensor gets the right amount of light. Without camera exposure controls, pictures taken at night would be pitch black, and those taken in bright daylight might be burned out. There is actually a fairly narrow ‘window’ of light intensities which sensors can record, and real-world lighting conditions vary […]