Exposure using studio flash

You need a light meter that works with flash

How do you know what aperture setting to use when employing studio flash as your light source? The answer is the same as when taking pictures using ambient light - you take an exposure reading of the light falling on your subject. But, you don't use an ordinary exposure meter; you need a "flash meter," a light meter that accurately measures the brief burst of light from the studio flash system.

FLASH METER

There are various makes and models of flash meter available. Quality, brand-name units are generally highly-reliable and differentiated more by their features than by their flash metering accuracy. For instance, some advanced flash meters will also read ambient light, or a mixture of ambient and flash light. Or, they might provide the photographer with lighting ratio measurements when using two flash heads, scene contrast measurements, built-in filter factor correction and so on. The flash meter may have interchangeable flat and domed diffusers, or an accessory that will allow the meter to take reflected light readings for accurate spot metering from the camera position.

BASIC FEATURES

A standard flash meter has

STEP-BY-STEP OPERATION OF A FLASH METER (with a sync cord)

If your flash meter permits measurement of either incident or reflected light, select the incident light metering method for this example. It is the simplest and most convenient method, and is suitable for most scenes.

1. Install the battery or batteries, and press the power button to turn the flash meter on.
2. Set the film speed and select the X-sync shutter speed you intend to use.
3. Connect a sync cord to the flash meter's sync terminal. (Check to see if your meter needs to be set to "cord" mode for use of a sync cord, and set it accordingly. This is usually accomplished by pressing the Mode button.)
4. Connect the other end of the sync cord to the flash system's connection.
5. Turn on the flash system.
6. Position the flash meter near your subject, within a couple of inches.
7. Aim the domed receptor directly at the lens of the camera.
8. Depress the meter's measuring button, triggering the flash and making the exposure reading.
9. Look at the flash meter's display, which will show the aperture needed for correct exposure.

Disconnect the sync cord from the flash meter and attach it your camera's sync terminal. Be sure your camera is loaded with film of the same speed that your flash meter was set for, and that your shutter speed will synchronize for flash - generally the X setting. Make your aperture selection using the setting recommended by the flash meter's reading. You are now ready to take a properly-exposed, flash-illuminated picture.

Note that some flash meters can be operated without having a sync cord connected. See Metering studio flash for instructions.

Is that all there is to it? As with many techniques in photography, the answer is yes.... and no. When you are using multiple flash units or reflectors, you should use the flash meter to obtain more than one reading, i.e. from different areas of the scene, so that your lighting ratio will be as you wish it to be. You may find, for example, that the illumination from your main light will properly expose the subject, but that you need to adjust the intensity of your fill lighting to improve the lighting ratio.