Dual 580 EXII master/slave problem

I have two 580EX II and wanted to have master/slave, but have only the slave fire (no ratio set). On page 39 of the manual, it shows how to accomplish this. However, the master still adds quite a bit of light, filling in shadows, like maybe a 1:3 or 1:4 ratio. The master still fires during the shutter being opened (1/160).

The manual states the master will still fire a pre-flash, but that should occure before the shutter and therefore should not affect the exposure. I turned the master flash head backwards, which helps diminish the fill output of the master flash, but is something amiss? Is there something else I have to do so the master flash doesn't act as a fill?

really interested to hear what people have to say, i am having the same problem with my 580ex I

Nothing is amiss. That's the way the system works. The master, even when disabled, does fire at the time of exposure to trigger the slave(s). Work around it as you did by aiming the master's head away from the subject.

oldvultureface wrote in post #14755730
Nothing is amiss. That's the way the system works. The master, even when disabled, does fire at the time of exposure to trigger the slave(s). Work around it as you did by aiming the master's head away from the subject.

Sorry to disagree but this is NOT how the system works. You can absolutely set up your master so it does not fire during exposure.

Press and hold the Zoom button on the back of the master unit until the you see either "Slave-On", "Master-On", or "OFF". Use the scroll wheel to choose Master-On and then press the center of the scroll wheel to select.

Now, give the Zoom button quick presses until you see a blinking "on" and a blinking symbol which shows the flash firing. Rotate the scroll wheel again until you see "OFF" blinking and press the center of the scroll wheel again to select.

If you did it correctly you will see the display read Master but you will not see the symbol (3 horizontal lines) at the flash head diagram.

Even when set as you describe, there will still be some flash visible when the is shutter open.

If you point the 580EX II "master" at a mirror and take a photo, you will see the trigger flash in the mirror. Usually this is not a problem, but in some situations this could add some light to photo. (high ISO, very short distance, etc.)

msowsun wrote in post #14767155
Even when set as you describe, there will still be some flash visible when the is shutter open.

If you point the 580EX II "master" at a mirror and take a photo, you will see the trigger flash in the mirror. Usually this is not a problem, but in some situations this could add some light to photo. (high ISO, very short distance, etc.)

The pre-flash happens before the shutter is open and will not affect the image

The master has to send a FIRE command when the first curtain is completely open or just before the second curtain closes. If you are close to the subject some of this command light will be captured.

The effect of the final trigger flash with the master disabled is subtle but visible. Try it. Then aim the master away from the subject and note the difference.

StanNJ1 wrote in post #14767453
The pre-flash happens before the shutter is open and will not affect the image

Yes, but what you need to do is mount your 580EX II on your camera and stand in front of a mirror and take a photo. Please report back to us after.

580 on camera aimed at Pat, 430 high and camera right. Both firing (A+B+C):