The big bang has arrived The much anticipated Sea & Sea YS-250 finally arrived. After prying it out of the staff's hands I was able to put it through a few quick tests. Sea & Sea recently updated the published specs and based on my tests the specs are inaccurate. It's common knowledge that all manufacturers specs are slightly inflated. After testing the YS-250, I decided to test our other popular strobes. Based on the results Sea & Sea YS-250 performs very well. To see a comparison read Underwater Strobes Compared.
Wide circular flash tube The YS-250 shoots a wide and warm color temperature beam similar to the other strobes in the big bang class. Smaller strobes with square reflectors are indeed bright for their size, but all have much cooler (cold) color temperature.
Guide number and recycle time My tests on the YS-250 produced a guide number of 22 (land, ISO 100, meters) and not the advertised guide number of 32 (land, ISO 100, meters). However it remains at the top of the class with all popular strobes in the US market. (For more details see Underwater Strobes Compared) At first my tests produced a faster recycling time than the advertised 1.8 seconds, but after a few cycles it appears to be an accurate rating. With the power dial set one click down the recycle is almost instant.
Size, weight, and buoyancy Think of the Sea & Sea YS-250 as a stretch-lemo version of the YS-120. It's the same girth, but just slightly longer. Unfortunately this trim size has lost the positive 1/2 lbs. buoyancy offered by it's predecessor the YS-350. Much like other strobes on the market, the YS-250 weighs in at negative 1/4 lbs. in the water (approximately 0.24 lbs. in salt water). If you're shooting a heavy housing, you should consider buoyant strobe arms such as Ultralight buoyancy arms and the foam float Stix arms.
Bright LED target light With a press of a button you can turn on a surprisingly bright LED target light. It won't replace a high quality housing mounted focus light, but is a nice back-up light.

12 level manual power control - the best feature! The Sea & Sea YS-250's greatest feature is a 12 level manual power control. The ability to have a strobe this bright, but with the ability to shoot at very low output will open the door to images that are difficult to pull off without a pocket full of diffusers. Shooting very close subjects or in very low ambient light conditions requires just a tiny pop of light. Based on my tests the 1/2 and 1/4 power markings are inaccurate. Each click from full to -11 is approximately 1 stop. Thus the YS-250 actually offers Full to -11 stops of control. In fact the lowest setting is such a quick flash that my light meeter had a difficult time recording it. Very exciting! Sealed battery compartment - easy to clean connectors The Sea & Sea YS-250 battery compartment is sealed from the internal electronics and the connectors are right on top making it easy to clean if you get sloppy. Further the battery seal design has an o-ring before the threads which will minimize drips when taking off the cap. Sea & Sea YS-250 Underwater Strobe: optional spare NiMH Battery Conclusion I'm happy with the raw power and warm beam of the YS-250 and thrilled with the 12 power level manual exposure control. However, I'm disappointed with the loss of positive buoyancy. I guess I'll be forced to use buoyancy arms, but can't wait to work at the low end of these strobes at sunset.