Canon 577G

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Professional grade flash created for Canon's 1971 flagship F-1 FD mount camera. Launced in 1971, it is still Canon's most powerful flash. It is designed for use with Canon legacy FD-mount bodies and connecting it to a the hot-shoe of a Canon 20D (and probably other modern DSLRs) produces the infamous ERR99 message. However, it has a low trigger voltage and can be connected to almost any camera or trigger by means of external sync sockets. The detachable auto thyristor sensor unit named G20 has a to two-pronged socket that accepts a Canon Synchro Cord A. This cord can be plugged into the pc sync. socket of any camera or trigger fitted with a pc sync. socket for auto thyristor operation. In addition, the flash itself has a pc-socket that can be used to trigger it in manual mode.

It features three auto thyristor ranges (f/2.8, f/5.6, f/11 @ ISO 100).

Default coverage optimised for a 35 mm lens (FX). Comes with , that extends coverage to fit a 24 mm lens (FX). With optional Wide Adapter 577G-20, coverage extends to fit a 20 mm lens (FX). With optional Tele Adapter 557G, coverage becomes optimised for a 100 mm lens (FX).

The Canon Speedlite 577G does not have an internal power source. To power the unit, use the Canon Transistor Pack G, which accepts either six C-size alkaline batteries or the Canon rechargeable Ni-Cd Pack TP.


Generic flash.
Head: Fixed 35mm coverage.
Swivel & tilt: -120° to +120° swivel, 0° to +120° tilt.
Exposure mode: Auto.
Manual settings: 1/1 only.
No built-in wireless modes.
Features: Sync. socket, Hammerhead.
Trigger voltage: 4.7 volt.
Batteries: 6xC.
Flash duration: 1/400 sec. @ 1/1 (full output).
Field upgradable: No.
Dimensions: 99 x 245 x 107 mm, 600 g.
Guide number (ISO 100, meter): 48.

Discontinued: Yes.

For a detailed explanation of the above specifications, see the guide.



Brand profile

Key info

Established: 1937
HQ: Tokyo, Japan
Web: Global, EU, US, man

Canon is a multinational corporation headquartered in Tokyo, Japan specializing in the manufacture of imaging and optical products. Its products including cameras, lenses, flash units, scanners, photocopiers, printers and steppers (used in semiconductor fabrication). The company was founded in 1937 as Precision Optical Instruments Laboratory and renamed Canon Inc. in 1947.

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