This post represents a bit of monolithic dual avicide. First, there is the exercise itself, using fast shutter speeds to isolate a frozen moment of time in a moving subject. Second, it gives me a chance to discover something that I have long been curious about, just what does the beginning of a stream of water running from a tap look like?
This was my first attempt. The set-up appears simple, an outside tap and an Olympus E-30 on a tripod and set to ‘machine-gun mode’ (rapid sequence). I would start a camera sequence and turn the tap on and off while the camera is running. As always, the devil is in the details.
As noted in the brief, there is a trade-off between shutter speed and ISO. My first set of images were taken with the kit 14-42mm zoom at the 42mm end (84mm full-frame equivalent) and its widest aperture, f/5.6. The image above was taken at ISO800, 1/320 second, which is not fast enough to freeze the water emerging under pressure. I also tried 1/800 at ISO1600 and 1/1250 at ISO2500, which was too noisy. After that I switched to the 50-150 telephoto zoom which opens to f/2.8 at the short end and allowed me shutter speeds of 1/1600 and 1/2000.
The second issue is timing, which is largely a matter of luck. Although 1/1600 is fast enough to freeze the water flow, the 5FPS sequential shooting speed is not great for capturing the fast-moving leading edge. Here are a few images in full flow, and we see that it is not a simple symmetrical cylinder of water.
Another issue was getting the full stream in focus with a shallow depth of field. This is the reason for the later images being more side-on, but including the white pipe in the foreground.
With the tap turned off, the last dregs of water fall under gravity and rather slower.
And, yes, I did manage to freeze that leading edge.
This final image is my favourite, from 150 total shots.