I need a flash that can keep up with my D300s in sequence capture mode. I am taking photos of bungy jumping, and need to reliably illuminate the subject. Currently during the day we just click away, and get great results, but we are heading into the period where we will be jumping at night, and need to keep the same consistent photos. A number of possabilities exsist, but nothing that has really all the features that I am looking for: I'd like a flash much like a DMX strobe light that are used in night clubs, something that you can set the intensity on, and that flashes at high frequency. I want to be able to send a flash trigger signal to the flash every time the camera takes a picture, and that the flash has no need to refresh. I don't need TTL, but I do need to be able to remotely increase and decrease the flash intencity from either the camera, or some sort of RS232, or such interface which can be controlled remotely. Flashes would be mounted close to the subject, and placed at various locations, for the shots, as the subject moves in a space that is 47 meters off the ground, and about the same in width. But realistically, it's only the top of the bounce, and the exit shots that we need. Alternative to this might be to have a number of small flashes, which can each be set manually for power output, and a simple switching trigger router. At default state the first frame would trigger flash A, then the second trigger would trigger flash B, and so on, perhaps with 4 flashes at the various sweet spots. The physical switch, which switches which flash is triggered, would have a reset switch to bring it back to start, so flash A would always be first. Is there a flash that is controllable with RS232?