| Jaron Berman |
August 29th, 2007 02:55 PM |
Look in the manual, but likely it's 1/200 or 1/250.
A nikon firing a nikon system flash, or a canon firing a canon system flash can indeed fire far quicker than "sync" speed. BUT, that is the only way to do it. If you're using studio-type strobes, or any other brand of flash on the camera, stick to the specified speed in the manual (1/200???).
Now, this can be a bit misleading. You may think that with a speed of 1/200, you'll get crazy blur. You might, if the flash is not fully lighting your scene. But think of it this way - the amount of time your flash is "lit" is the amount of time the sensor sees light. That's how a shutter works - the amount of time its open is the amount of time it sees light. The flash duration itself effectively becomes the shutter speed. My Elinchroms fire at 1/2600 - meaning that no matter how long I leave the shutter open, the exposure of objects lit only with flash WILL NOT CHANGE. The effective "freezing" power of my flash will be equivalent to continuous light, and a shutter speed of 1/2600.
Now back to what was mentioned before - if you set the speed faster than the fastest safe sync speed, you MAY on occasion get lucky and have a properly exposed frame. MAYBE. More likely, a slice of your frame will look correct, and the rest will be black. Essentially you're trying to "catch" that 1/2600 flash burst somewhere while your shutter is open. The longer the shutter is open, the more likely you are to catch that burst. Flashy sync systems to external trigger are not terribly accurate, which explains the slow sync speeds, and why manufacturers can allow faster syncs with their own propreitary strobes. With a flash on the shoe, they can also calculate the exact length of wire and circuit trace between the sync signal in the camera and the trigger for the flash - meaning they can make it work consistently (as opposed to the external sync, which on low end cameras can vary by huge amounts even among the same model).
Sports illustrated (and ESPN mag) and other large sports photo depts. often set up multiple remote cameras and strobes during arena sporting events. To distract the crowd less, they only hang (usually) one set of lights, all sync'd together. Then all of the cameras are sync'd, and a master trigger can fire all at the same time, or only specific cameras. Regardless of how many of the cams fire, they all sync the same set of strobes. Thy often mix medium-format cameras (1/60 sync) with digitals (up to 1/500 sync). To allow this to happen, they use a fairly slow sync speed, but extremely powerful strobes turned down very low in order to speed up the flash burst. This has the effect of freezing action, even with long shutter durations.
So the moral of the story is: with enough light hitting the subject from strobes alone, and with strobes that fire short flash durations, the actual camera sync speed is mostly irrelevant. just make sure its slower or equal to the max "safe sync" speed of the camera.
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