Optical Slave

[John E]

Is there any optical slave flash out there that will work with a Canon flash -- that is, without being fooled by the pre-flash? Or do I have to turn off the pre-flash when using any kind of optical slave? I want to light up a portrait background and don't want to have to sacrifice one of my 580 EX II's to do it. Any suggestions are appreciated :).

[Paul Li]

No pre-flash in manual mode.

[Titus213]

There are digital slaves on the market that say they will ignore the pre-flash. I've not heard any great reports on them working.

As Paul Li said, put it in manual mode.

(I did not consider flash units, just triggers...)

Paul's advice is still good - manual mode, no pre-flash to worry about.

[Psychobiker]

The Yongnuo YN460 ignores the preflash, reliably

[watt100]

The Yongnuo YN460 ignores the preflash, reliably

my YN460 will trigger from a preflash, (when set on s1 or s2) maybe I'm doing something wrong

[Psychobiker]

That's odd. Take another flash, set the YN460 to S2 and press the test button on the other flash in very quick succession. It should only fire on the second flash

[shutterfiend]

http://www.bhphotovideo.com/c/product/263022-REG/Wein_W940001D_PN_Peanut_Slave_100_.html

http://www.bhphotovideo.com/c/product/263024-REG/Wein_W940030D_HS_D_Hot_Shoe.html

[watt100]

That's odd. Take another flash, set the YN460 to S2 and press the test button on the other flash in very quick succession. It should only fire on the second flash

I don't have another flash, the popup preflash on a 450D definitely triggers the YN460 with the mode set on s2

[shutterfiend]

I don't own this flash but this ebay listing (http://cgi.ebay.com/YN-460-Flash-Speedlite-For-Canon-5D-350D-400D-450D-500D_W0QQitemZ280387779848QQcmdZViewItemQQimsxZ200 90821?IMSfp=TL0908211710003r15104)suggests that S1 is the pre-flash mode.

[Paul Li]

YN460 isn't supposed to do that in S2 mode - maybe try contacting YongNuo?

[Titus213]

OK - I rest my case.

[bulldogg7]

My XS has preflash in manual mode, I have to use a cheapo flash to trigger slaves. Unless I use S2 which just fools the ETTL and blows out the shot.

[watt100]

I've only had the flash for a few days (still experimenting). I can turn off the preflash in the custom menu and/or shoot in manual mode so the preflash trigger is not a big deal.

[FlashZebra]

I've only had the flash for a few days (still experimenting). I can turn off the preflash in the custom menu and/or shoot in manual mode so the preflash trigger is not a big deal.
You cannot turn off the preflash that is used to set exposure on the built in flash on any Canon DSLR.

Enjoy! Lon

[watt100]

You cannot turn off the preflash that is used to set exposure on the built in flash on any Canon DSLR.

Enjoy! Lon
seems to work on my model, when I set custom function 7 on my 450D "only external flash" emits the preflash does not fire on Tv or Av mode

[FlashZebra]

seems to work on my model, when I set custom function 7 on my 450D "only external flash" emits the preflash does not fire on Tv or Av mode
You cannot turn off the preflash that is used to set exposure on the built in flash on any Canon DSLR.

You cannot tell just by looking. The preflash is very quick and subtle.

But an optical slave, the title of this thread, will have no problem distinguishing this pre-flash as a distinct flash and fire the connected flash before the exposure flash (not enough time to recycle the power capacitors).

The only way to turn off the exposure setting pre falsh is to use the FEL (Flash exposure lock) button. But this is only turns it off temporally and you must accomplish a pre exposure first. Hardly a very satisfying or robust way to turn off the exposure pre flash.

Enjoy! Lon

[watt100]

You cannot turn off the preflash that is used to set exposure on the built in flash on any Canon DSLR.

You cannot tell just by looking. The preflash is very quick and subtle.

But an optical slave, the title of this thread, will have no problem distinguishing this pre-flash as a distinct flash and fire the connected flash before the exposure flash (not enough time to recycle the power capacitors).

The only way to turn off the exposure setting pre falsh is to use the FEL (Flash exposure lock) button. But this is only turns it off temporally and you must accomplish a pre exposure first. Hardly a very satisfying or robust way to turn off the exposure pre flash.

Enjoy! Lon

all I can say is it works on my camera, I swear! I can distinctly see the popup preflash when half-pressing the shutter and the AF assist beam is enabled, (Tv mode), when I change the custom function "only external flash emits" there is no preflash in Tv mode with the popup flash

[liupublic]

all I can say is it works on my camera, I swear! I can distinctly see the popup preflash when half-pressing the shutter and the AF assist beam is enabled, (Tv mode), when I change the custom function "only external flash emits" there is no preflash in Tv mode with the popup flash

That's not pre-flash. That's a short flash to assist auto-focus in low light scene. Enable it again and see if you will not see that early flash when you press half way down. The custom function allows you to disable onboard flash's AF assist beam. That will disable both the IR and that AF assist flash.

Pre-flash goes out immediately after the shutter is pressed all the way down. And you can not disable ETTL on Canon's onboard flash. Therefore, you can't disable pre-flash.

[watt100]

That's not pre-flash. That's a short flash to assist auto-focus in low light scene. Enable it again and see if you will not see that early flash when you press half way down. The custom function allows you to disable onboard flash's AF assist beam. That will disable both the IR and that AF assist flash.

Pre-flash goes out immediately after the shutter is pressed all the way down. And you can not disable ETTL on Canon's onboard flash. Therefore, you can't disable pre-flash.

:p I wasn't pressing the shutter all the way down!
that AF beam was prematurely setting off the external flash, If this is the case maybe the YN460 is ignoring the preflash. I've only had the flash for several days, obviously I need to do some more experimenting!