Flash Duration

A client needed a water vortex shot last week. The shoot was a lot of fun but it also demonstrated the dramatic effect that flash duration can have on an image.

We used a glass cylinder about 10in diameter by 14in high, bought from a local furniture store, which was filled with water. A wooden spoon was used to get the water moving then a battery powered drill with a paddle contraption fine-tuned the vortex.

Behind the cylinder was a sheet of perspex which was back-lit with an Elinchrom Digital 2400 RX pack and head. The resulting test shots proved the set-up was going to work but the resulting images showed noticeable blurring of the swirling bubbles which was a big problem as the client was demanding sharp images with the water showing no movement. This was not what we were getting from our test shots.

I swapped out the Elinchrom pack for a Profoto Acute B and shot a few more test frames. When viewed on screen the result were dramatic. The Acute B produced noticeably sharper images – the bubbles sharp – frozen by the shorter flash duration.

There was also a noticeable difference to the colour of the image. The Elinchrom image had a slight sepia feel to it when compared to the Profoto which produce a very neutral image.