The ISS2000 is a non-TTL strobe slave that is one of the best values for a flash unit on the market. The four power settings plus a diffuser (to further soften the output) allow the user to adjust the flash for optimum camera exposure. The best way to perfect this is by testing and familiarizing oneself with the various flash settings in different underwater depths and conditions (e.g. visibility range due to ambient light or clarity of the water. Spending 2 times or more money on a TTL flash unit can make it easier to take photos; but with a little practice on a non-TTL strobe like the ISS2000, you can get great underwater photos that are perfectly exposed. Using a strobewill greatly improve the color of your photos and eliminate the problem of backscatter. There are other ways to improve color and reduce/eliminate backscatter without using the flash. One of the most effective is manual white balance, which should be reset at every 10 feet of depth. to help compensate for the loss of warm colors such as red, orange and yellow. A red filter can also help add these colors back into your image. Using a flash diffuser will help eliminate backscatter when using a cameras internal flash. All in all however, an external strobe is one of the best accessories to purchase for improving your underwater photography. It will add light, bring back natural colors and eliminate backscatter.