To shoot motion blur, it’s essential that the camera be set to manual. The flash sync should be set to either FCS or RCS, depending on the look of the shot you’re trying to achieve.
Shutter-speed, which is what allows blurring of the image, needs to be anywhere between 1/4 and 1/15th sec.
The slower it is, the more blur you can achieve. Remember, however, that slowing the shutter-speed will also allow more ambient light onto the sensor, and can lead to over-exposure.
A small aperture (f/16-f/22) helps to minimise ambient light but also to control the strobe light and to guarantee sharp focus of the subject.
The ISO must be set low (50-200), again to minimise ambient light.
Twin strobes should be used on high power, and set behind the camera-housing handles in the quarter-to-three position. It’s the strobe light that “freezes” the subject and the ambient light that allows for the blur, so the trick is to get close to the subject to allow the strobe to overpower any ambient / available light.
Removing strobe diffusers creates “hard” directional light to light and “freeze” only the foreground subject.
“In-lighting” can also work very well, to prevent illumination of the background. This strobe positioning and power would normally result in horrendous backscatter, but with the panning technique the backscatter just gets blurred away, and can even add to the overall effect.
I generally start at ISO 100, 1/8th sec and f/18, with my strobes on almost full power. If it’s very bright, I’ll stop down to ISO LOW/50, 1/15th and f/22, and if too dark, ISO 200, ¼ sec and f/16.
These same settings can be used to produce creative and artistic pictures such as swirls or zoom blurs.
Bright sunshine with the sun directly overhead will result in over-exposure because of the slow shutter-speeds needed for motion-blur effects.
Minimise the ambient light by shooting on cloudy days or early/late in the day. In very bright conditions, neutral density filters can be used to control excessive ambient light.