Flash Exposure Meter

A flash exposure meter can give exposure reading in reflected light and incidental light and can detect a one-tenth of an F-stop difference in light levels.

A digital sensor has less dynamic range than negative film. It resembles slide film-If you get the exposure just a little bit off, the resulting images are less than desirable. Software such as Photoshop etc, can correct exposure via curves and levels. However, by needing to redistribute tonal qualities in an image, valuable detail suffers in the process.

If you look at the histogram of an image that has been manipulated in this manner, gaps will be apparent. This is to show that there are no pixels present in those tones. By using a hand-held meter, to gather exposure information, your image will need little or no tonal correction in Photoshop.

When you need to measure flash exposure, you can either set meter to:

Using a Flash Exposure Meter

To use a hand-held flash exposure meter, first you set the ISO rating. You do this by pressing the ISO button. Then you set the mode (ambient, just a sun symbol) flash, or corded flash. These also from a button push or wheel spin, depending on the make of meter. 

Your meter will either have a sliding opaque semi-sphere, (Like half a ping-pong ball) or one that can be attached. For reflected readings, detach, or retract this semi-sphere from the metering cell.

Point the flash exposure meter slightly downwards, to avoid too much light from the sky. Then press the measurement button to get a reading. Readout will display shutter speed/aperture combination for correct exposure. 

You can then use either a wheel or up/down buttons to cycle through the different combinations. This is to suit speed of subject or aperture for desired depth of field and transfer these settings to your DSLR. 

When you want to take an incident reading, use the semi-sphere over the metering cell. Stand within the subject’s plane, and point meter to where photo is to be taken from. Adjust buttons accordingly.

Using Meters at Weddings

Your camera uses reflected light readings for exposure. Light reflected from different subjects will result in a range of tones which your camera’s meter will try to average out. This should give an overall correct exposure. 

It may not matter sometimes but because any little deflection of lighting will give a different reading, and if you are photographing a wedding for instance, it could look as if photos were taken on different days!

You may have noticed at weddings that the pro photographer will hold a meter at the bride’s face. Pointing to where the camera will be. This is taking an incident light reading which actually measures the light falling onto the subject.

It is not affected by the tonal differences of the subjects colouring as the light falling on any subject in the frame will be constant. Therefore the incident reading will ensure that there will be detail in the black tuxedo. The white of the wedding dress will not be blown out.