September 15, 2011

Canon Speedlite 420EX Reference Page

Canon Speedlite 420EX front
This is a reference page for the Canon Speedlite 420EX which has been a valuable assistant in filling-in and background lighting my setups for several years.

The 420EX was originally introduced by Canon as a cheaper alternative to Speedlite 550EX while it could also perform as a companion, by being able to accept remote commands from 550EX in Slave mode.

Having had some frustration with early YongNuos, I had purchased 420EX used, at a very attractive price, exactly for its slave function.

Beside that, it worked very well on top of EOS 400D /Digital Rebel XTi mostly as a bounce flash. However, there are some incompatibilities with crop factor digital cameras concerning the zoom ratio translation as the flash unit was designed with Canon film cameras in mind.

Further, the 7 points assist beam may not cover all AF points of even the EOS Digital Rebels.

On the other hand, if one is to use it as a bounce or off-camera flash none of the latter has any importance.
In my opinion 420EX is still today one of the best alternatives to cheap imitations when used as a slave unit.

The Flash

Features & Specification
  • Maximum Guide Number 138 at 105mm setting; G.N. 101 at 35mm setting.
  • Approximately 1/2-stop less powerful than 550EX.
  • Full E-TTL flash operation with "Type-A" bodies.
  • E-TTL features include high-speed FP sync mode, and FE Lock.
  • Fully compatible with EOS-1v, EOS-3, Elan 7 series & D30.
  • Powered by four AA-size batteries.
  • Totally TTL-compatible with all "Type B" EOS cameras.

Flash Modes:E-TTL, TTL
Guide Number:138
AF Assist Beam:7 points
Bounce / Swivel:Yes
Wireless Triggering:Yes
Dimensions:2.8 W x 4.8 H x 3.9 D in
2.8 W x 4.8 H x 3.9 D cm
Weight (without battery):370 gr (10.6 oz)

Canon Speedlite 420EX operations guide diagram
Canon 420EX whereabouts (Photo by courtesy of Canon Camera Museum)

Canon Speedlite 420EX stand, flash & leather case

The Flash Foot Stand

Canon Speedlite 420EX flash on foot stand

The Carrying Case

The old type genuine leather case has small pocket for the flash stand.

Canon Speedlite 420EX leather case

The Battery Compartment

Canon Speedlite 420EX battery compartment / loading

The Flash Head

The head is equipped with safety lock rubber button on one side
Canon Speedlite 420EX right side

Canon Speedlite 420EX flash head release button

Canon Speedlite 420EX left side

Canon Speedlite 420EX flash head tilt positions

A secondary safety button releases the head swivel function independently.

Canon Speedlite 420EX flash head tilt marks & swivel release button

Canon Speedlite 420EX flash head tilt & swivel

Canon Speedlite 420EX flash head swivel pos

The Mounting Foot

Is made of hard plastic with 5 connectors for the E-TTL function of the unit plus a small safety pin that extends when the flash locks on the camera hot shoe.

Canon Speedlite 420EX flash Mounting Foot

Flash Controls

Canon Speedlite 420EX back controls

Canon Speedlite 420EX E-TTL & zoom lights

Canon Speedlite 420EX slave switch & group/channel selectors

Canon Speedlite 420EX control panel off

Canon Speedlite 420EX control panel on

Mounted on a Camera

Canon Speedlite 420EX on EOS digital T2i / 550D rear

Canon Speedlite 420EX on EOS digital T2i / 550D front

Canon quality construction.
Canon infrared Slave mode at the flip of a switch.
Very attractive second hand price.

No manual mode.
Not compatible with the latest on camera Flash Control menus.
Does not recognize between crop factor and Full Frame cameras.

For shure the age of Speedlite 420EX is obvious compared to contemporary Canon speedlites and although it has some limitations lacking a full manual mode, I still think that if it is found used in a good condition it can be a very good choice against cheap imitations. First for beginners experimenting with bounced flash with E-TTL capabilities and second as a very good slave for fill-in or background flash for those starting to experiment with multi off-camera flash.

I hope you found the reference useful, thank you for viewing.
All Photos & Photosynths: © 2010-2012 S.C.Vlachos

Canon Speedlite 420EX can still be found used in good condition at very low price either from Amazon or from eBay.

Relevant Articles:

Canon Speedlite Transmitter ST-E2 Reference

Canon Speedlite 580EX Reference

Canon Speedlite 430EX II Reference

Canon Speedlite 580EX II Reference

Relevant Readings:

Canon U.S.A. Speedlite 420EX

Canon Camera Museum Speedlite 420EX Technical Report

Speedliter's Handbook at

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