1. What to Buy?
- basic fundamentals of lighting
- fundamental of off-camera flash
- lighting for your work
2. Flash Duration
With natutal light
- High speed shutter to capture the motion
- for splash, 1/1000s is needed
While with the flash speed
- Maybe 1/40s is good enough
- The flash duration capture the motion
- shutter speed is irrelavant
The higher power, the longer flash duration
So to capture splash, use low flash output power
3. Sync Speed
The max speed camera can set to work properly with flash
Why limit? since In high shutter speed, the shutter should not fully open, so ther would be a dark area
Shoot as max sync speed
4. Flash Power
The more powerful, the more control you have on the depth of field
For flash, the power if linear