EACHSHOT MK-910 MK910 i-TTL Flash Speedlight 1/8000s HSS(High Sync Speed) Master for Nikon with Diffuser 1, i-TTL mode, monitor pre-flashes are fired at all times. The subject is correctly exposed by the light from the flash lighting and the exposure is less affected by ambient light. 2, Advanced wireless lighting, with advanced wireless lighting, wireless multiple flash operation in the TTL (i-TTL)mode can be accomplished with CLS-compatible digital SLRs. In this mode, you can divide the remote flash units into three groups and control the flash output independently for each group, expanding your range of creative multiple-flash shooting techniques. 3, AF-assist illuminator, in autofocus operation, the MK910 emits AF-Assist illumination, which matches the wider AF area of CLS-compatible cameras. With cameras supporting this function, autofocus photography in dim lighting is possible even when the camera's focus point (focus area) is changed. 4, Supports power zoom function, automatically adjusts the zoom position to match the lens focal length. Setting the ISO sensitivity, the ISO sensitivity is automatically set based on information from the camera.