Both strobes must have some type of sync cord to operate with the Olympus housings, so it must be considered in any comparison. Sea & Sea requires their fiber optic cord which allows only manual operation, prohibiting TTL use of the strobe. The Ikelite DS-51 with a Manual Controller also provides only manual operation, but puts the adjustment for its 10 power settings conveniently at the housing rather than up on the strobe like the YS-90DX. The Manual Controller is the sync cord with its built-in slave sensor.

The Ikelite DS-51 has the same intensity and angle of coverage regardless of erroneous advertising claims, recycles faster, and is less expensive. It can be ordered in cost saving packages that include a new ball socket arm system compatible with TLC and ULCS arms.

Ikelite also offers a TTL Slave Sensor which does not provide multiple manual power settings with the DS-51; it provides complete strobe automation by "watching" the strobe that is built into the camera.

The Ikelite housing for Olympus C-5050 cameras allows direct hard wired connection of Ikelite SubStrobes by sync cord for manual use.

It is not fair to compare the Ikelite DS-125 to the YS-90 series which do not effectively provide even 90 degrees coverage, do not recycle in one second, and do not include rechargeable battery packs.