Slave for 420EX

[nelson cotrim]

Can I attach an optical slave to the 420EX? I know it works as a slave

with either the 550EX or the ST-E2 transmitter, but they are both way

expensive for me right now. I know I lose E-TTL, I just want to know

if it will work, and if it may damage the flash in any way.

 

Also, when I fire the flash manually (press the pilot button) will the

flash use full power? Thanks.

[NK Guy]

>Can I attach an optical slave to the 420EX?

 

Attach? I don't know what you mean. Optical slaves are flash units which fire

in response to a burst of light from another flash unit. So there's nothing to

attach, per se.

 

Unfortunately the 420EX will always issue an E-TTL prefire flash when used

with type A camera bodies, and this prefire will trigger most optical slave units,

resulting in the slave firing too soon. (ie: the slave will fire in response to the

prefire flash, not to the subject-illuminating flash)

 

However, there are now optical slave adapter units which are designed to

respond only to subject-illuminating flashes and not prefires. I don't know how

well they work, but they're out there. They're little devices which you fasten to

the hotshoe of your slave flash unit.

 

Alternatively you could either a) use the 420EX flash with a type B camera

body (the 420EX reverts to TTL-only flash in this case and will not fire a

preflash) or you can tape over one of the flash contacts and use the flash with

your type A body. If you go the taped contact route you'll also lose second-

curtain sync and FP flash. There are instructions on how to do this taping on

eosdoc.com.

 

More alternatively you could buy a cheap Sigma EF 500 Super flash unit and

use it to master your 420EX in wireless E-TTL mode.

[nelson cotrim]

NK, I want to use an optical slave adapter, mounted on the 420EX´s hotshoe, which will trigger it in response to a burst of light from another flash unit (ie the built-in flash in my EOS Elan II).

Example:, I´m very distant from my subject, let´s say a bird, and have time to prepare the shot, so I mount the 420EX on a tripod with the slave attached, and fire it using my built-in flash. I´m just concerned if this might damage the flash in any way (fry the circuits). I don´t think so, cause there is no batteries on the adapter, just the light sensor.

[jimstrutz]

If you mean that you want to attach an optical slave triggering device to the hot foot of your 420EX... ...yes and no.

 

You can attach it & it won't do any damage to the flash, but it probably won't work either. Then again, it might. Most Canon Speedlites, when attached to an optical slave trigger will fire once & then lock up. But some of them work fine with some slave triggers. Model numbers seem to be no help in determining which will & which wont.

 

My 550EX will not work with any of the optical slave triggers that I have, but others have reported that their Speedlite works fine with them. Other have reported that using a Canon Off Camera Shoe Cord 2 in between the slave trigger and the Speedlight makes every thing work, but that didn't work for me either.

 

Pressing the "open flash" button will always be full power with the 420EX. With a 550EX you can reduce the output for this in manual mode.

[nelson cotrim]

Jim, that was exactly what I wanted. I remembered there was some problem using slave adapters, just couldn´t remember. This locking up was the problem, not damage. Thanks a lot guys.

[NK Guy]

Aha. My apologies for misunderstanding your question. Jim's

answer is what you want.

[nelson cotrim]

NK, thanks anyway. You answered something I wanted to ask: the Sigma being the master. I was unsure if it could be a master and slave or only a slave.