L-758 Cordless flash mode to set aperture help.

I read the manual, tried searching, and couldn't still understand this.
I have a 580Ex and a 430Ex in Ettl.
I set the L-758 to 1/125s, cordless flash (Multiple). So now all I have to do is to trigger the flash multiple times until I reach the aperture I want.
All good.
Say the first time I trigger the flash I get 1/125s f0.5.
The second time is f1.1, then f1.8 (just examples).
How do I adjust the camera's exposure? (Which is on M by the way).
In other words, the flash output hasn't really changed, but it's the lightmeter that is accumulating the flashes to reach the aperture. So what settings am I supposed to change on the flash or camera then?
I think that I am getting old and stupid

If you trigger the flash 5 times and it says f/4, then you set the camera's aperture at f/4 and fire the flash 5 times to get correct exposure.

But you should be using your flashes in manual mode.

Flash units set to manual mode. Lower the Lumisphere and stand (not blocking or otherwise interfering with the flash output to the meter) at the subject location. Trigger each flash separately while aiming the unit at the flash to be recorded from subject location, note readings for each and adjust accordingly.
Raise the Lumisphere and trigger all the flash units at the same time while taking the measurement from the subjects location in relation to the camera. Make sure you have the unit pointed at the camera lens when taking the reading. This will give you the proper EV to make the shot.

The most crucial thing is to measure from the exact location of the subject while not blocking any light. With the Lumisphere down, it helps to block and stray light from other sources.
The more accurate you are with subject location the better.
I don`t always turn off the other flash units, but I use my body to block them out. It`s a little faster to get to the final setup this way.

Hatem Eldoronki wrote in post #9187386
I read the manual, tried searching, and couldn't still understand this.
I have a 580Ex and a 430Ex in Ettl.
I set the L-758 to 1/125s, cordless flash (Multiple). So now all I have to do is to trigger the flash multiple times until I reach the aperture I want.
All good.
Say the first time I trigger the flash I get 1/125s f0.5.
The second time is f1.1, then f1.8 (just examples).
How do I adjust the camera's exposure? (Which is on M by the way).
In other words, the flash output hasn't really changed, but it's the lightmeter that is accumulating the flashes to reach the aperture. So what settings am I supposed to change on the flash or camera then?
I think that I am getting old and stupid

The first problem you are having is that the meter is not reading a realistic output from your flash units. When the Speedlites are in ETTL mode, they emit a fairly weak pre-flash for the purpose of calculating the required output for the main burst. THAT is what your meter is seeing, and it's a meaningless light level.

You must have both the camera AND all of your Speedlites in manual mode in order to make the meter at all useful. Then, you can set the output levels of the flash units, measure the available light from them at the subject's location with the meter, and then set the camera's ISO and aperture for the flash exposure.

Setting the camera's shutter speed to a speed slower than the "max sync speed" lets you include a bit of the ambient lighting in your images. This requires a measurement of the ambient lighting based on the aperture setting and ISO values you've chosen for the flash exposure. The meter will show you what shutter speed to use for a full exposure with ambient light and you need to choose how much faster to set the shutter speed to get the level of ambient light you want in the image.

As soon as I posted this, I realized the ETTL oversight. Thanks for that.
What I really don't get is that while metering cummulatively, how does the number of flash triggers on the L-758 translates to camera/flash settings.
So if the L-758 tells me I need 5 flashes to get to f8 for example, how do I set the flash for this?
Curtis N, how do I fire a flash 5 times @ 1/125s for the final shot? (I am almost a virgin to flash stuff

Thanks a lot for your superfast replies already!!!

Hatem Eldoronki wrote in post #9187696
So if the L-758 tells me I need 5 flashes to get to f8 for example, how do I set the flash for this?

I do not believe there is any way to make Speedlites do a set of sequential flash bursts (when triggered by the camera) to accomplish what you are trying to figure out.

If you manually fired a flash unit (by pressing a button on it or a button on a cord connected to the flash), then you could fire the flash five times. You'd have to wait for the flash to recycle each time before manually firing it.

You would also have to keep the camera's shutter open in "bulb" mode for the entire time it takes to do the multiple flash pops. In order for this to work without overexposing the image, the ambient light would have to be almost totally dark because you're dealing with a minimum of about a ten second exposure for five manual pops of the Speedlite.

Skip, it is posible to make speedlites fire multiple times in a single shot, however, not at 1/125s as far as I know.

Hatem Eldoronki wrote in post #9187919
Skip, it is posible to make speedlites fire multiple times in a single shot, however, not at 1/125s as far as I know.

Can you make the Speedlite fire a controlled number of times and while it is in manual mode?

I don't know about the Canon 580 EX (II) but the Nikon SB-800 or B-900 will not fire multiple flashes in manual mode. You would have to fire them manually as you would with a studio strobe.

drdiesel1 wrote in post #9187442
I don`t always turn off the other flash units, but I use my body to block them out. It`s a little faster to get to the final setup this way.

As much as I do like and use this method, there's no question that you will get different readings when comparing the light off to blocking with your body or hand. When exposure or an exact ratio is crucial I will turn the other lights off to measure each one carefully.

Not in manual, but in Multi mode on the flash unit.

If you tell us exactly what it is you are trying to do or achieve, we might be able to help you out. Your first post talks about you trying to meter for what sounds like multiple flash exposures. Now you're talking about something different altogether, i.e. the Mutistrobe mode of the flash.

Hatem Eldoronki wrote in post #9187696
Curtis N, how do I fire a flash 5 times @ 1/125s for the final shot?

You don't.

Multiple flash mode is a specialized function of some flash meters. For most kinds of photography, one burst is all that is practical.

Why are you using the meter in multiple flash mode to begin with?

Hatem Eldoronki wrote in post #9189424
Not in manual, but in Multi mode on the flash unit.

If the Speedlite (and the camera) is not in totally manual mode, using a handheld meter to measure its output is a completely pointless effort.

If you are using the Speedlite in any mode but manual, the Sekonic meter will not tell you anything useful about the Speedlite's output and you cannot translate any readings it does make to the camera. This is because the meter has been seeing the Speedlite's pre-flash and triggering on that. The only way to avoid the pre-flash is to operate the Speedlite in manual.

PacAce wrote in post #9189744
If you tell us exactly what it is you are trying to do or achieve, we might be able to help you out. Your first post talks about you trying to meter for what sounds like multiple flash exposures. Now you're talking about something different altogether, i.e. the Mutistrobe mode of the flash.

Okay okay...
I am trying to shoot my daughter with one flash as key light bounced off an umbrella, and the other flash with a snoot behind her.
I am using an EF 100mm (and my daughter is 9 months old and moves fast), so I want to set the camera to 1/125s, but also the aperture to f5.6 to f8.
The L-758 will not let me adjust the aperture. In the owners manual it says that you can't, and you have to fire the flash multiple times until you reach the desired aperture reading. And it stops there.
Therefore I asked for help. Somebody said I had to fire the flash as many times as the it takes the meter itself to achieve the aperture I want in the picture-taking stage, which is impossible. So I said that was only possible in Multi stroboscopic mode, which is NOT what I had in mind from the beginning, but just mentioned it to answer him.

This is a general question regarding the L-758:
What I really would like to understand is how am I gonna benefit from knowing that it takes sixteen flashes to reach a given aperture as my meter says?