These photos were a test to see which underwater strobe worked better with my
Canon S40. The Ikelite DS125 was tested in TTL mode. It faithfully did exactly
what the Canon internal flash did. However when there was inadequate light from
the internal flash, the DS125 also produced inadequate light.
The Sea&Sea YS90DX was operated in manual mode. I tested it in full power, in
both the preflash setting, and the "on" (no preflash) setting. In the preflash
setting it ignored the preflash and synced with the camera .
It produced all the light I needed. In the no preflash setting, it wouldnt sync correctly,
as expected.
Conclusion: The manual mode of the YS90DX was superior to the TTL mode of the
DS125. The TTL mode of the DS125 would not produce enough light when matched to the
Canon S40.