First Attempt at Water Drop Photography

[qleak]

The more concerning relation between flash duration and water drop motion blur is the distinction between t.5 and t.1 duration of the flash.

The stated manufacturer specifications are for a t.5 time which means the flash has reached 50% amplitude by this time. The t.1 time for an sb700 at full power is approximately 1/300 second which is not quite fast enough IMHO. At 1/2 power it's approximately 1/1000 which is certainly fast enough for most situations. At 1/32 and 1/64 the durations are <= 1/8000 second so are at least as fast as any shutter speed.

Here's where I got the measured t.1 times.

 

[Judobreaker]

Actually I think this is one of those cases where you may be wrong...
The average water drop has a terminal velocity of about 5-10 m/s (depending on the size).
So lets take the optimal number and say our drop is falling 5 m/s. That's 5000 mm/s.
Sooo... In a flash burst of 1/1,000th of a second that drop will travel 5mm, which is actually quite a lot...
In 1/40,000th of a second however the drop travels 0.125mm which won't be too much of a blur.
I'm thinking you shouldn't make the power too high.

A few points of interest in your math... First off, in these setups water rarely has the time to hit terminal velocity. Water droplets will reach terminal velocity in about 6 feet (give or take), and most of these setups release the droplets within a couple feet of the impact zone. Also, it's (generally) not the drop falling that people want to take photos of, it's the aftermath of its impact with water which drastically reduces the droplet's speed.
But math is fun, so thanks for the numbers!

Numbers are cool.
But yeah, you have a good point.
Even if you divide the speed by 5 though it'll still be 1mm of movement in 1/1,000th of a second so it's still something to keep in mind.

 

[mingxuan]

very excellent job! I like it