How fast is a flash? (~1ms?)

[dlwalke]

I took a series of pics tonight varying only the shutter speed (aperture, ISO, and subject constant). The pics were pretty comparable at shutter speeds from 1/1000 s all the way up to 1.3 s. The pic made at 1/1600 s was noticably darker. I surmise that this means that the flash emits light for something more than 1/1600 s but no more than 1/1000 s. Does this sound reasonable?

And is this duration pretty similar from one flash to another?

 

[Don Burke]

I took a series of pics tonight varying only the shutter speed (aperture, ISO, and subject constant). The pics were pretty comparable at shutter speeds from 1/1000 s all the way up to 1.3 s. The pic made at 1/1600 s was noticably darker. I surmise that this means that the flash emits light for something more than 1/1600 s but no more than 1/1000 s. Does this sound reasonable?

And is this duration pretty similar from one flash to another?

There is also the sync speed of the camera to consider. The flash duration is not the only issue. The amount of flash while the shutter is open is the issue.

One millisecond sounds reasonable for slow flashes.
Automatic flashes can be pretty fast when there is plenty of light. I have seen specifications for 1/30,000 s on some flashes.

A photo repair shop would have access to gear to measure flash duration.

Being a cheapskate, I would take some pictures of a fast rotating object and figure it out from there.

 

[MarkH]

Whenever I want to measure flash duration I shoot a bullet into an apple (or a lightbulb if I'm hungry), take a picture and see how blurry the bits are.

 

[Tortuga Roja]

From Ikelite:

For the DS125, full power is approximately 3 milliseconds and half-power is 1.2 milliseconds.

For the DS50, full power is 1.6 milliseconds and half-power is 650 microseconds.