#1. "RE: sb-50 as a TTL slave" In response to Reply # 0
silly-can valley, US
SB50 slave has automatic mode and manual mode.
If you set Sb50dx to automatic slave mode (sensor can detect master light around 7 meters away), then it is still TTL (specifically you have to set camera to standard TTL, not matrix TTL, there is no master speedlight preflash, which may trigger the slave prematurelly). I think this applies to all wireless slave (such as SB28+SU4), as the face the same issue.
If you set sb50dx slave to manual mode (which can detect master light 40 meters away), then, no TTL as SB50 can only fire at maximum power in that mode, master light cannot controll over it except trigger it.