MT600C New Functions: 1, The set-top ETTL flash: Install it on the Canon camera to achieve automatic flash photography 2, Optical singal SLAVE control functions: Automatic wireless remote control flash(optical pulse) 3, Autofocus auxiliary functions 4, Automatic zoom functions, flash zoom position can be back and forth with the change of the focal length of the lens 5, Supporting the access to the Canon menu. 6, The MT600C appears to be very compatible with the YongNuo YN-622C and YN-622C-TX. Specifications: Guider number: GN60 (ISO100, 200mm) Wireless Flash: Optical pulse transmission Salve Flash mode: ETTL, M, MULTI Zoom range: Auto, 20~200mm (When using wide angle dispersion plate is 14mm) High speed sync: 1/8000s Slave flash: Optical pulse SLAVE Canon, light trigger, S1/S2 Shutter Synchronization: Hight Speed Sync, Front-curtain Sync and Rear Sync Flash exposure compensation: Support (with an increment of 1/3 gear in +/-3 gear) Bracket exposure: Support Flash exposure lock: Support Modeling flash: Support AF Assist-focus: Support Manual flash: 1/128~1/1 (with an increment of 1/3 gear) Fraquency flash: 1~199Hz Recycle time: Quick flash less than 2s, ordinary flash less than 3s Optical transmission distance: about 20m Optical transmission channels: 4 Flash Groups: Support for A/B/C groups Power supply: 4 x AA size batteries (Alkaline or Ni-MH is usable) External interface: Hot-shoe, PC synchronous interface, external charging interface, external expansioninterface Battery life: Flash 100~700 times Mesaurement: 79.7 * 142.9 * 125.4 mm Net weight: About 420g (not including batteries) Package Listing: 1x Mcoplus MT600C 1x Stand 1x manual