Light beam and GN comparison
We've taken the new Retra Flash (pre-production spec) and made a comparison of light beam and Guide Number (GN) performance with two popular underwater strobes.
Strobe #1 (left) - Strobe #2 (center) - Retra Flash (right)
All strobes are without light modifiers.
All strobes were positioned 30 centimeters from a white wall and set to fire on manual power settings. With the help of a light meter we were able to achieve the same exposure in the center of the light beam and observe how the shape and intensity changes with angle.
We then compared the GN of all three strobes by measuring the exposure value at maximum power in the center of the light beam. Here are the resulting measurements:
- Strobe #1:GN32
- Strobe #2: GN 24
- Retra Flash: GN30