I love experimenting with strobes, and one day I wondered what running water from a faucet would look like with a very quick flash.
To start, I took a picture of water running from a tap at 1/250 of a second (with a continuous light source):
Although it's kinda cool (it sorta resembles a painting actually), it's not exactly what I was looking for. I wanted to see what flowing water looked like if time was frozen, and for that, you need to use a flash with a short duration.
A quick teaching point for those who aren't experienced with strobes - for most pictures, your effective shutter speed (I made that term up) is your actual shutter speed, because the light around you is on for the entire shutter duration (that is, the light is always on during the period your camera shutter opens and closes. Let's say you are taking an outdoor picture lit by the sun. If your shutter speed is 1/250th of a second, the sun is "on" for that entire time, so your effective shutter speed is 1/250th of a second). However, let's say you can create an environment where you only have one light source (ie a strobe), and you have that strobe create a very quick burst of light (say 1/8000th of a second), then go dark. Even if your camera shutter is open for 1/250th of a second, because the only light it sees lasts 1/8000th of a second, your effective shutter speed is 1/8000th of a second. I hope that made sense!
Okay, back to tap water. For the next photo, the actual shutter speed of the photo is the same (1/250th of a second), but in the previous pic, the light was on for that full duration, so that's what flowing water looks like at 1/250th of a second. In the following picture, I used a Broncolor strobe set at 1/8000th of a second to try and freeze motion.
Pretty cool, right? Maybe a tad geeky, but that's basically what water out of a tap looks like at 1/8000th of a second. Now, there's still a bit of blur in the picture, although I must preface this by stating this picture is basically a straight RAW converted to JPEG - no sharpening has been applied whatsoever. That said, the cause of the blur might partly be due to lack of critical focus (I used the Nikon 105mm macro, and achieving front to back focus is tougher as you're much closer to the subject), but before I took the shot, I placed a plastic business card in the flowing water and made sure the text was tack sharp, so focus shouldn't be the issue. My guess then is that even at 1/8000th of a second, the water is still flowing fast enough to cause a slight blur, and hence, a bit of softness in the picture.
Finally, I decided to try taking the same picture with just a normal speedlight (Nikon SB910) at 1/128 power (manual mode) to see what the picture would look like. Given that the speedlight is about 10% the price of the Broncolor strobe, I expected the results to be more blurry (ie the flash duration would be longer than 1/8000 of a second), and here's what it looked like:
Whoa! The results are every bit as good, if not better, than what the Broncolor produced. Now, the Broncolor picture was stopped down to f11 and the SB one f8 (meaning that the Broncolor's light output was twice as intense as the speedlight), but if you don't need the power, and if distance to the subject is not an issue (in this picture, the SB was basically 20cm from the running water), the speedlight can produce results every bit as good as a significantly more expensive unit. Of course with the Broncolor Move, you get color temperature accuracy, much less variance of light output between shots, the added benefit of significantly more power when needed (at a much lower flash duration as well), and a host of professional light modifiers (amongst other things), but this is still pretty incredible from the little SB unit.
Finally, here's a picture of both the Broncolor and the Nikon, with some sharpening applied (SB on the left, Broncolor on the right) - pretty neat, eh?
Now some of you might be wondering what the point of this all is as taking pictures of tap water really isn't going to take a photographer that far. That's true, but the ultimate goal is to take things we can practice with (in this case, running tap water), and apply them to a more complex shot. I'll show one application of this in my next blog post!