Exposure Value
The exposure can be defined as a number that indicates:
- when negative, underexposure
- when positive, overexposure
- when it is zero, a correct exposure
The exhibition is the result of 3 major elements in photography:
- ISO (sensor sensitivity to light)
- Shutter speed (time during which the sensor is exposed to light)
- Aperture (hole allowing the light to pass through the lens)
Correct exposure is obtained by playing on the value of these 3 elements.
The unit used to measure this quantity is EV (Exposure Value) or IL in French (Lumination Index), also referred to as LV (Light Value) or stops, all of these terms are synonymous.
Increasing + 1EV is equivalent to doubling the amount of light.
The luminous intensity of a scene can be defined by its amount of light. The more luminous it is and the larger its EV, the following table summarises the classical cases:
Scene: Brightness (EV)
Black Night: -15
Full Moon: -3
City by night: 3
Church: 5
Interior of a house: 7
Las Vegas by night: 8
Cloudy periods: 10
Sunset: 11
Sky Cover: 13
Great Sun: 15
Great sun at sea / snow: 16
Use
The tool allows you to either determine:
- the speed and the ISO according to the chosen aperture (mode 1)
- aperture and ISO according to the speed chosen (mode 2)
Mode 1
1. Unlock the aperture by clicking on the? (if it's positioned on the aperture)
2. Set the value of the desired aperture by turning the wheel or by clicking to enter the value
3. Set the desired exposure value
In the bottom area
4. You get:
ISO and speed corresponding to exposure and aperture
5. You can transfer this data to the equivalent exposure calculation tool
Mode 2
1. Unlock the speed by clicking on the? (if it's positioned on the speed)
2. Set the desired speed value by turning the wheel or by clicking to enter the value
3. Set the desired exposure value
In the bottom area
4. You get:
ISO and aperture corresponding to exposure and speed
5. You can transfer this data to the equivalent exposure calculation tool