I purchased the SL-960D for a trip to Cozumel in December 2005. I selected this product based on a budget limit of $350, and what I could determine about it's capability and quality from reading other reviews.
FEATURES: Uses 4 "AA" batteries. All of my other camera equipment for this dive trip used "AA"'s and I didn't want to have to deal with proprietary battery packs, so this was am important feature for the flash unit.
LIGHT-POWER: The SL-960D is a single-head strobe with a Guide number of about 17 at maximum power output. Professional U/W photographers almost always use dual-head lighting systems with Guide numbers of 50 or more, but this was out of the question for my budget. The "range" of the SL-960D, in which it gave best results, was 2'~4' from the camera to the subject. The camera was a Canon A-620, a P&S with a pretty small lens and a maximum aperture of 2.8 (not really great light gathering power). A digital SLR with an F1.4 lens would probably have achieved better results from this relatively low powered flash gun. That said, I was able to get some really amazing stills on the 17 dives in which I had the flash gun mounted. When everything was just right, fish not moving too fast and at the "just-right" distance from the camera, clear water with no suspended particulates, and the optimal camera settings, the photos were better than I could have hoped for clarity and color. But, if the subject was beyond 5'~6', the light from the flash gun was usually too dispersed and weakened to make much difference. In other words, this flash gun did a decent job within it's design limitations, but don't expect miracles. In all fairness, this was my first dive trip in which I took high quality U/W camera equipment; my lack of expertise and experience probably meant that I lost a lot of shots that a professional would have gotten with the same equipment.
The SL-960D unit is triggered by slave-strobe from the camera's built-in flash. On about 1 in 20 shots, the SL-960D failed to fire or if it did fire, it was not synchronized properly to the camera shutter. With this in mind, users are recommended to take duplicate shots of important subjects, so "bad" shots can be deleted. The SL-960D has a dial to regulate power output, but I quickly discovered that the unit isn't powerful enough to bother with "low" settings; I left it on full power for the rest of the vacation after the first dive.
I used 2000mAH NIMH cells in the SL-960D, and averaged about 60 shots per dive using flash; the flash never ran out of battery power on a dive. Build quality of the unit felt okay for the price. The polycarbonate housing and battery loading hatch are fairly thick and the hinges and locking latch feel like they are of reasonably good quality. The mounting plate and flexible arm worked well on the Canon WP-DC90 camera housing. The flex arm was easy to hold and provided a good grip for the left hand.
CONCLUSION: If your budget for an underwater flash gun is limited to less than $400, the SL960D is probably the best unit you will be able to afford. But, if you can afford to spend more, like maybe $1000~$1500, a dual head Sea and Sea or Ikelite lighting system offers a lot more power, which will enable you to use smaller lens openings and faster shutter speeds. NOTE: The SL960D is flash-strobe light for still photography, it is NOT a continuous-emitting light for videography.
Buy Reefmaster SL-960D SeaLife External Flash for Digital Cameras!
