Best Business Practices for Photographers [19]
Back in the days of film, I'd use a Hasselblad, and I'd be at 125th of a second at f/22, photographing a subject in the midday sun on ISO 100 film, and I'd want the sky to be deeper than the one stop under that it currently was, so I'd stop down to 250th, and I'd lose a little of the pop directed at the subject. At 500th I'd lose one and a half stops of light, and I'd be stuck. I had to return to, at best, 250th, all because the flash duration was longer than the time the shutter was open, and with all the settings the same, just a shutter speed stop-down, I was losing light.
More recently, I was involved in photographing an ad campaign in which we were shooting day for night. Typically, this is done when you need a scenic vista with some degree of illumination—at night—and you don't have any way to light it. You allow the sun to be your background light to give tone to the shadows, but you want it three to four stops under your strobe, and that means ISO 50 at 250th at f/22 with some clouds cutting the sun down. Having a strobe system with a short flash duration will ensure that you can make a photo of this scene and meet the client's needs. When the ad in this case was delivered, everyone except the art director and subject who were on set was convinced that the shoot had taken place after sunset, yet it had taken place under midday sun.
To understand flash duration, picture a line graph in which the light output looks like a bell curve. At the moment the shutter is tripped, the stored energy in the flash pack begins to be discharged and the element in the bulb begins to brighten to its stipulated power. The first few milliseconds are when the light output is increasing, from zero to a few watt-seconds, and during the next few milliseconds the bulb achieves its maximum brightness and light output and then begins to power down. As it discharges and the power output diminishes back to zero in the last few milliseconds, the illumination is complete. Less like a bell curve and more like a spike means a shorter duration in power up/peak/power down. As a result, a short-duration flash will not have its "tails clipped" as the shutter closes while the flash is still producing output. If all your photography takes place at 125th of a second or slower, and you rarely find yourself using full power on the strobes, then flash duration might not be important to you, nor will it have a significant impact. However, if you get the call for a big assignment that calls for intricate lighting, or you don't want your creativity clipped by long flash duration lighting kits limiting shutter speeds and maxing out at f-stops to "stop down the sun," then you will want a professional-grade flash system. There are, in all fairness, only two systems that can deliver on this level when it comes to battery-powered packs. They are the Hensel lights and the Profoto Pro-7bs. The other systems work well; however, when tasked with the aforementioned big assignment, having—and being familiar with—the right equipment means you will be able to deliver repeatedly.
One last point about lighting equipment that might seem tangential to lighting but is integral: When you arrive at an assignment, don't have multicolored cases, bags, and such. From the outside, your cases should look like they are pieces of a cohesive unit. Typically, this means sticking with one brand or (the safe bet) all black. And when your cases are opened, they should look like the person who packed them knows what he or she is doing. Every time I peer inside the toolbox of an auto mechanic, I am amazed by how every tool is clean and neatly