A handheld light meter measures the light itself and tells you what aperture, shutter speed and ISO to set for a correct exposure. Set the ISO, point the meter’s dome toward the camera from your subject’s position, take a reading, and dial the suggested values into your camera.
Incident and Reflected Readings
Meters work in two ways. An incident reading measures the light falling on the subject, using a white dome that you hold at the subject and aim at the camera. Because it ignores how light or dark the subject is, it gives consistent results with white dresses and black suits alike. A reflected reading measures light bouncing off the subject, the way a camera’s built-in meter does, and it can be fooled by very bright or very dark scenes.
Basic Steps for Any Reading
- Set the ISO on the meter to match your camera.
- Choose the mode: ambient light, flash, or a cord or radio triggered flash mode.
- Decide which value you want to fix, such as the aperture for depth of field or the shutter speed for motion.
- Stand where the subject stands and hold the dome near their face, pointed at the camera.
- Press the measuring button.
- Read the suggested setting and dial it into the camera.
- Take a test frame and check the histogram, then adjust by a third or half stop to taste.
Using It in the Studio
With flash, set the meter to flash mode and connect it by cable or radio, or use the test button to fire the lights. Read each light on its own to balance the key, fill and background. A common approach is to set the key light, then adjust the fill so it is a chosen number of stops lower. In the studio, aperture is the main control, since the flash duration usually freezes motion. Keep the camera’s shutter speed at or below the sync speed in the maker’s guide.
Using It Outdoors
- Take the reading in the same light the subject is in, not in your own shade.
- Recheck when clouds move, since outdoor light changes quickly.
- Use a spot meter attachment, if your meter has one, to read small areas like a face in a shaded scene.
- Take separate readings for highlights and shadows to see the contrast range.
Why Bother When the Camera Has One?
A camera meter gives a fast guess based on what the lens sees. A handheld meter lets you set exposure before the shot, keep results steady across many frames and judge flash output without trial and error. It also helps with film, where there is no screen to check.
FAQ
Do digital shooters need a light meter?
Not strictly. The histogram and screen work well, but a meter speeds up studio lighting setups and keeps exposures consistent between frames.
Can a phone app replace a meter?
Some apps read reflected light reasonably, but they do not read flash or measure incident light like a dedicated meter. Check what the app maker says it supports.
The Short Version
Set ISO, measure at the subject pointing toward the camera, and copy the reading to your camera. In the studio meter each light, outdoors recheck as light changes, and fine tune with a test frame.
