Digital Photography Tips and Techniques

The flash output level of a Nikon SB-600 Speedlight Flash can only be set to the minimal of 1/64 in manual mode. That leads many people to speculate the minimal output from the flash is 1/64. If you have used the Nikon Creative Lighting System (CLS) Advanced Wireless Lighting (AWL), you will know that you can use 1/128 output setting on the wireless commander unit. The wireless commander can be the built-in flash of your camera, or SU-800 commander, or SB-800/SB-900 Speedlight flashes. The question is what happens when the remote flash is a SB-600. Will it actually output 1/64 or 1/128 of light when the commander tells it to do 1/128?

To answer this question, I ran a test with a flash light meter to measure the output of the SB-600.

The setup

I used a Nikon D200 to wirelessly control the output the SB-600. The built-in flash was setup as commander, with built-in flash output set to “–” and group A set to M mode. The SB-600 was setup as a remote flash in Group A. The zoom head was left at 24mm. If you are familiar with Nikon’s AWL, you will know that  the built-in flash will emit a series of so-called “monitor pre-flashes” (Nikon term) to setup remote flashes, communicate flash output level data to remote flashes, and trigger the remote flash when the shutter is open. The “pre-flashes” can cause a light meter to incorrectly measure the flash output. To avoid this problem, I used the Nikon SG-31R IR Panel for Built-in Flash to block the visible pre-flashes. Infrared signals can still pass through and trigger the flash but the light meter can no longer be fooled. The light meter I used was Polaris SPD100 Digital Exposure Meter. I used ISO 100 and sync speed of 1/200s on the light meter. The distance between the flash and the light meter was one meter.

The results

The flash meter gives a reading accurate to 1/10 of a stop. The measurements are given as aperture value + over exposure value. For example, “f/2 + 1/10″ means camera setting of  f/2 at ISO 100 will over expose by 1/10 stop with the light coming out of that flash.

At each output level, the measurement was repeat three times. There are some variations but mostly within 2/10 of a stop.

Conclusion

By using the SB-600 as a wireless flash unit, you can get manual flash output level less than 1/64. As one of our readers, Russ, noted in the comment section below, it is possible to get even less flash output in TTL mode.