Mr.Ft Loc: Central New Jersey

Hi, I found my old canon 420 EX flash while cleaning out some boxes. My question is can this be used on my Canon 5D m4 or my 80D. I'm being told by some locals that it will mess up the main board in the cameras. If that is true would it work as an off camera flash with a wireless trigger. I know it is about 35 years but you never know till you ask!

Thanks
Tom

jdubu Loc: San Jose, CA

EX flashes are good to go with current Canons.

Mr.Ft Loc: Central New Jersey

correction, that is a 420 EZ flash, my mistake.

jdubu Loc: San Jose, CA

It will work in manual mode only. Not ETTL compatible.

CHG_CANON Loc: the Windy City

Consult your EOS manual for confirmation. It would seem those giving potential risk advice are mistaken.

For example on page 234 of the EOS 80D, the manual indicates the EZ flashes are compatible, but they fire only at full-strength in A-TTL or TTL mode. The recommendation is to develop a manual exposure on the camera that accounts for the amount of light fired by the flash. For flashes that have a manual mode, use the flash's manual mode to reduce the full-power output.

Test your flash and see how it works. I tend to use the manual flash set-up on my EX flashes to control just the exact amount of light created by the flash. I didn't pull the manual on the 420EZ, but if it provides a manual option, it just takes some practice to get familiar with the process.

amfoto1 Loc: San Jose, Calif. USA

I was going to say! 420EX isn't that old.

Previous responses are correct....

The 420EZ (or any other Canon "EZ" flash) will do no harm to your camera. It has a low trigger voltage, so is safe to use.

The EZ flashes were designed for use with EOS film cameras, way back in the 20th century. Some of those cameras were very susceptible to flash trigger voltages... I'm pretty sure some models (including the EOS-3 and Elan 7/EOS-33 that I used) had a 6 volt limit! So the EZ flashes have ultra low trigger voltages.

Modern DSLRs... if memory serves, everything made from around 2004 onward... are designed to tolerate 250 volts! So a flash with under 6 volt triggering will certainly do no harm to them.

See other responses regarding limitations using an EZ flash on today's ETTL compatible cameras. I don't know the details... I only have EX flashes for use on my cameras.

Back when cameras were purely mechanical, no one worried about flash trigger voltages. Some flashes... such as certain versions of the popular Vivitar 283 and 285 models... tested with trigger voltages as high as 400V. You certainly wouldn't want to use one of those directly in a modern camera's hot shoe! There are "isolators" such as Wein SafeSync that can be used.

Cameras gradually acquired electronics. Initially, in the 1970s, it was just electronic shutter control and metering systems. Those circuits were pretty robust so there still wasn't any concern. Early AF systems were fine, too. But in the 1990s cameras became essentially mini-computers, and that's when they started getting susceptible to things like flash trigger voltage. The fine circuitry involved was poorly shielded and largely unprotected as cameras used more plastic and less metal in their construction. In the early 2000s the manufacturers got together and decided to do something about it, since digital was in full swing and complex, miniaturized circuitry was taking over. I think it was around 2004 that they settled on and agreed to a minimum standard of 24 volts flash trigger voltage tolerance... but I know for certain that both Canon and Nikon exceeded that by a large margin, building their cameras to tolerate up to 250V flash trigger voltage. I think I've seen similar specs from Camranger, Pocket Wizard and some other flash and strobe-related products... which also may have to be concerned with flash trigger voltages.

KAT007 Loc: Waukesha, WI

I have been using my 420EX with my 7D II for a few years now. Before I put it in the hot shoe, I first contacted Canon support for the OK. Even though it’s from my film days, they reassured me that any EX flash is safe to use. For the most part, I use it off camera.

nadelewitz Loc: Ithaca NY

"Some locals" are ignorant of Canon flash systems.

A 420EX flash can safely and effectively used ON a Canon digital camera... DSLR or bridge camera. That's what it was made for. The limitation is it is auto only---no manual setting ability. E-TTL only. So maybe not effective for off-camera use with a remote trigger. With a camera-to-flash extension cord, fine.

A 420EZ, the older series introduced for the original EOS film cameras, can also be be used on digital cameras (acting in A-TTL mode), and has the benefit of manual settings too, so it's ideal for off-camera use, wireless as well as with an extension cord.

ALL EZ and EX flashes, being made for EOS autofocus cameras, have low enough trigger voltages so as to not be harmful to modern cameras.