The Canon Speedlite 577G is a powerful handle mount flash unit with external power supply designed expressly for professional photographers.Made to function with Canon manual focus SLR cameras and other cameras having direct contact accessory shoes or standard PC terminals, the 577G flash featuring three automatic flash ranges plus automatic bounce flash and a high Guide Number of 157 with ISO 100 film. The remote flash sensor mounts on your camera's accessory shoe to provide accurate automatic exposure control.
| Type | Handle Mount |
| Guide No. | 157 with ASA 100 |
| Angle of Coverage | 24 to 100mm lenses in 35mm format, using approate adapters |
| Auto Distance Range | Variable |
| Auto f/Stops | Full TTL at all apertures |
| TTL Dedication | Yes |
| Bounce Head | Yes |
| Swivel Head | Yes |
| Zoom Head | No |
| Recycle Time |
9 Seconds(based on fresh alkaline batteries & full power) 6 Seconds(based on fresh NiCd batteries & full power) |
| Power Source | Transistor Pack G |
| Dimensions | 2-7/8 x 4-1/4 x 9-5/8 in. WxHxD [with clamp & bracket] |
| Weight | 3 lb 2 oz with transister pack g (without batteries) |