Speedlight flash speeds


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Nov 1, 2011
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-How does the speedlight flash speed affect an image? For example speedlight flash speed set at 1/64 vrs 1/16?

-Why do some speedlight speed settings show an option between choosing 0.0, 0.3 and 0.7 in the small box next to the displayed speedlight speed? Is this an exposure value for the speedlight (how bright the speedlight flash will be)?

-Does the shutter speed on the camera need to be similar to the speedlight speed?

-Does the Exposure value (0.0, 0.3, 0.7) on the camera need to match the small box value on the speedlight (0.0, 0.3, 0.7)?
Those are power settings, not speed (though the speed is related). The lower the power, the shorter the flash duration - could be as short as 1/10,000th (maybe more).

The 0.0, 0.3, and 0.7 are thirds of a stop. 1/1 to 1/2 is one stop - 1/2 0.3 is 1/2 + one third.

Sometimes those numbers might be negative, depending on which way you're turning the dial.

1/2 0.7 is the same thing as 1/1 -0.3. You can't have 1/1 0.7 or 0.3... 1/1 is full power. There is no "full power, plus one".
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From my SB-600 manual:

1/900 sec. at M1/1 (full) output
1/1600 sec. at M1/2 output
1/3400 sec. at M1/4 output
1/6600 sec. at M1/8 output
1/11100 sec. at M1/16 output
1/20000 sec. at M1/32 output
1/25000 sec. at M1/64 output

As for the OP's next-to-last question, usually no. But there are cases where you want a higher shutter speen than is normally a 'synch' speed. But you need a camera & speedlight capable of doing so.
Speed of flash for high speed photography

FLASH Exposure Compensation (often referred to as 'EC' these days) is what the 0.0, 0.3, 0.7, 1,0, 1.3, 1.7, 2.0, etc,etc refers to. This is normally found ON THE speedlight itself. Not "always", but typically, on the FLASH unit itself.

Exposure Compensation, for continuous light, is a separate thing, usually denoted by a +/- symbol on a dedicated control, or setting,and this is always on the camera itself.

The flash and the camera exposure settings can be different, and do not "need" to be identical.

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