key concept Expos ure value
Discover EV, and how it works
Exposure Value, or EV, is a central concept in exposure. If you use a handheld meter, like this Gossen Digisix, it displays the exposure value directly. You can then use the dials to turn this into any combination of lens aperture and shutter speed. Handheld meters might seem quite slow by today’s standards, but they do encourage you to see exposure in a much more straightforward way.
The exposure value is displayed on the LCD panel.
You then rotate this outer dial to show the same value in this small window.
Now you can read all the possible shutter speed and aperture combinations on these scales
You can also slide this translucent dome over the metering window to take an incident light reading to measure the light actually falling on your subject, not just the light it reflects.