Nikon SU-4 Wireless Remote Slave TTL Flash Controller (with SG-2 Diffuser)
The Nikon SU-4 Wireless Remote Slave TTL Flash Controller is a compact, legacy optical trigger designed to enable off-camera wireless flash photography without any connecting cords. It mounts to the hot shoe at the bottom of a secondary Nikon Speedlight, turning that flash into a remote "slave" unit.
Key Functions and Features
- Optical Slave Firing: It features a built-in optical sensor that detects the instant your camera’s master flash (such as a pop-up flash or shoe-mounted flash) fires. It immediately instructs the remote flash to fire in perfect synchronization.
- Legacy Wireless TTL (Auto Mode): Unlike basic modern optical triggers that only support manual mode, the SU-4 features an intellectual "Auto" mode. It detects when the master flash stops emitting light and instantly cuts off the slave flash. This effectively mimics automatic film-era Through-The-Lens (TTL) exposure metering.
- Manual Mode: A physical switch allows you to toggle to "M" mode, firing the flash at whatever power setting you manually specify on the Speedlight itself.
- Audible Confirmation: It features a switchable electronic beep that sounds to audibly alert you if the flash fired correctly or if it missed the signal.
- Battery-Free Operation: The device does not require its own batteries; it draws power directly from the Speedlight it is mounted onto.
What is the Included SG-2 Diffuser?
The Nikon SG-2 is an on-camera flash panel diffuser included in the original bundle. [1, 2]
- The Problem: When using an on-camera pop-up flash to optically trigger a remote flash, that on-camera light can hit your subject directly, casting unwanted harsh shadows or ruining your multi-light portrait setup.
- The Solution: You clip the SG-2 bracket into the camera's hot shoe right in front of the pop-up flash. The white plastic shield blocks and diffuses the visible light so it does not affect the scene, while still letting enough infrared light leak out to trigger the optical sensor on the remote SU-4 controller.
)
