Summary: I do event photography, so it's fast moving and high volume. I no longer have to worry about missig a shot because my flash is too slow on the recycle, or because I'm changing batteries. I highly recommend this product.
Summary: The device is very useful. The best part is the fact that I can shoot for hours with this connected to the SB800 Would be much better if it had a shoulder strap or some way of carrying it other than on your belt or camera stap.
Summary: Very useful but frankly very overpriced for what it is. Use it when shooting longer events, such as weddings, and it was fantastic as I did not have switch out batteries ever and the recycle time was significantly reduced.
Summary: As I couldn't afford the Quantum batteries due to cost I bought a SD-8A to use with my SB-800. I also purchased 12 ea Delkin 2900mh rechargeable batteries. I routinely get 500+ flashes at each week's high school wrestling matches with power to spare.
Summary: Good performance, except that on the SB 800 it is only able to bring down recycle time to 2sec. Considering that the SB and this unit hold 10 cells vs. 5 of the SB alone, recycling time reduces 2.7sec to 2sec is not that much different. Also, after every 15 shots at full power, you are supposed to let the flash cool down for like 5 mins. Uhm, what?I think this is a bit of misinfomation/lying (intentionally?) on the part of the manufacturer.
Summary: It truly adds to the functionality on the venerable SB 800. Yes as a team SD-8A/Sb800, it would make me think twice before jumping to the SB 900. At the risk of repeating some of what was said by most of the other reviewers, I want to add some more relevance to this seamless match. Yes in my first full test to see how many shots I could get with it added. I got just under 800 shots at a wedding.
Summary: After always waiting for my SB-800 to recycle, those days are long gone. I just used mine for taking pictures at my daughter's play, and was able to take lots of full-power flashes (bounce in the theater). It's taken about 300 pictures on one charge so far with no sign of slowing down (spec says 380 on a charge). Most surprising to me was how light-weight it is, given the energy density (life vs weight).