Just wanted to share a few words today about shutter speed and flash sync for you photographers out there. Probably the most intriguing thing you notice the first time you shoot studio flashes is the sharpness of your photos. This is due in large part to:

1. Flash impulse being much faster than your “normal” shutter speeds.

2. No ambient or continuous light entering the equation.

When shooting with flash, you can get away with a surprisingly slow shutter speed, hand holding the camera (IF your only light source is flash). This is because, although you have a slow shutter speed, your subject will only be illuminated for the length of your flash impulse. This length is known as flash duration. For example, the image above was shot at 1/25 sec, f/8.0, ISO 100, at 70mm. The light source was an Einstein flash unit which gives about a 1/3000 sec. flash burst at 1/8 power. This means that although my shutter is open for 1/25, I am only making an exposure of my daughter for about 1/3000 sec.

You can see sharpness at 1/25 is just fine. I shot this handheld using a slow shutter speed for illustrative purposes. I would  normally shoot this at 1/200 or so which is about the fastest my 5d will sync with studio flash. Most cameras do have an upper limit for syncing with studio flash without banding problems. Typically this is around 1/250 for battery powered flash and about 1/125 for studio flash depending on the make and model. See this article for an excellent and detailed description of flash sync speed and how it works.

The same method can also apply outdoors when your subject is primarily lit with flash.

The problem with this however, is that the slower you make your shutter speed, the more your subject will become partially illuminated by flash and partly illuminated by available light. This makes the flash/ambient mix more of a balancing act, particularly as the ambient starts to fade and you need a slower and slower shutter speed to bring out detail in your surroundings or the sky. The image above is 1/30sec, ISO 250 at f/5.

You can see a bit of ghosting around my subject’s cheek due to the mixture of ambient light and flash having a bit of a conflict. The overall sharpness is decent, just something to be aware of as you push your shutter to its limits in hopes of keeping your ISO numbers down.

Another thing to be aware of- not all flashes have a quick duration. Small speedlights often have short durations such as 1/1000 and faster but some A/C powered studio flashes can be as slow as 1/200. Additionally, some studio flash units can get slower as the power is increased or decreased depending on the technology used to fire and extinguish the light. One reason I recently switched to Einsteins is because for A/C powered lights, the duration is very quick. So far, I am loving them. Stay tuned for a more detailed review of these lights as I put them through the paces on some actual assignments.

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