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PhotoNotes Flash Unit Specification.

Mastering Canon EOS Flash Photography

PhotoNotes Compatibility Lookup - Specifications for the Canon Speedlite 420EZ flash unit.

This flash unit, the Canon Speedlite 420EZ, was introduced in 1987 and discontinued in 1989. The product is a standard hotshoe-mounted flash unit intended for general purpose applications. Top of the line when it was introduced all those years ago, the 420EZ is an affordable flash unit for people who need a reasonably powerful flash that works with older TTL-only film bodies. However it lacks a critical feature that its successor, the 430EZ, has: flash exposure compensation controls. It's also fairly large and heavy. Do not confuse this unit with the similarly named, but totally different and much newer, Speedlite 420EX. As a TTL/A-TTL flash it also doesn't work properly with EOS digital cameras.

Flash metering.

The flash unit supports both TTL and A-TTL automated flash metering (when used with compatible cameras). Manual control over flash output is supported by built-in controls, with a power range of 1 to 1/32.

This flash unit is not compatible with digital cameras, and thus cannot meter automatically with them.

Guide number (power output).

The unit has a zooming flash head which moves internally to adjust for the lens focal length. Control over the zoom position is both manual and automatic. The zoom range is from 24-80 mm, with zoom detents (stops) at 24, 28, 35, 50, 70 and 80mm.

The flash zoom function is not capable of adjusting its position to compensate for the smaller image areas of APS cameras and some digital cameras. The unit thus essentially wastes light by providing enough coverage for full-frame 35mm film even when that isn’t necessary.

The unit’s guide number (provided in metres, not feet, for ISO 100) varies depending on the zoom head settings.

  • At 24mm the guide number is 25.
  • At 28mm the guide number is 27.
  • At 35mm the guide number is 30.
  • At 50mm the guide number is 35.
  • At 70mm the guide number is 40.
  • At 80mm the guide number is 42.
  • Autofocus Assist.

    The flash unit has a built-in red autofocus assist light, with a range of 0.9-8 metres. The AF assist covers a camera’s central AF point only.

    Flash head movement.

    The flash head can both tilt and swivel.

    Type A functions.

    This flash unit does not support E-TTL and does not support any advanced functions for type A cameras, such as wireless E-TTL. It also can’t be used with digital EOS cameras except in manual metering mode.

    Other features.

  • Support for second-curtain synchronization if the camera has the appropriate custom function.
  • Support for second-curtain synchronization via back panel control.
  • Back panel LCD (liquid crystal display).
  • Stroboscopic flash with a range of 1-5 Hertz (pulses per second).
  • Save Energy (SE) function, with a timeout value of 5 minutes.
  • Powered by four standard AA cells - alkaline, NiCad, NiMH.
  • Not compatible with lithium AA cells.
  • Plastic flash foot.
  • Weight: 350g.
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    This page was generated automatically from a comparison database. There is no guarantee that this database and display code are entirely free from error. Please notify me using the feedback form at the bottom of this page if you notice any inaccuracies.

    Information was derived from a number of sources, including Canon news releases, the Canon Camera Museum and Dave’s Speedlites Comparison Table, the Canon Speedlite Reference Guide, Canon Flash Work and various manufacturer-supplied product manuals.

    This information is accurate to the best of my knowledge, but I cannot take responsibility for purchasing decisions you may make.


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