What is your most often used metering system..

Evaluative and quick thumb with the exposure comp.

If lighting gets totally static then I just go right to Manual and frame-in my histogram to what I like.

JeffreyG wrote in post #8135295
In spot mode the camera meter attempts to expose whateve is in the spot to be a medium grey. But the reality is that it's going to be a rare shot that the tone in the exact center is medium grey. So spot meter in Av, Tv, P etc is probably going to generate some really inconsistent results.

The more common way to use a spot meter is in M mode, point the spot at various tones in the scene like the sky and the darkest shadows and then pick your settings that expose these tones the way you want them to look.

As for E-TTL, some people prefer center weighted average and some prefer evaluative. It depends on how you want the camera to deal with bright tones in the scene. CWA will tend to blow out highlights with the flash while evaluative will hold highlights at the expense of underexposing everything else.

Bingo!

shooting live music, i use partial 99% of the time. i shoot in manual, and chimp the histogram to fine tune if needed. if lights are changing, i'll adjust shutter speed w/ my best guess as it goes.

timnosenzo wrote in post #8137516
Your flash is still using your cameras meter (and metering mode) to calculate the exposure. ETTL is an automatic mode, using preflash to calculate a correct exposure, then emitting however much light is necessary to make a proper exposure. If you have the camera in spot metering mode, and when the flash tries to calculate the exposure it's pointed an a black suit, the flash is going to think the scene is darker than it really is, and it's going to overexpose. Or the opposite. Just like using an auto mode on your camera with spot metering.

You can treat your flash metering like your camera's metering. With spot metering turned on, you can use FE Lock to meter a particular part of the scene, then use FEC to increase or decrease the flash exposure. Again, I don't think most people do it this way.

thanks tim!!!

Matrix mode on the D50 , partial on D70 and some times spot but occasionally matrix,
on the eos 300D it is evaluative (it decides for you)

Depends. Most of the time Eval. Sometimes in Spot.

Spot, AI Servo, AWB, manual mode............. RAW, Faithful everything zeroed out.

timnosenzo wrote in post #8137516
Your flash is still using your cameras meter (and metering mode) to calculate the exposure. ETTL is an automatic mode, using preflash to calculate a correct exposure, then emitting however much light is necessary to make a proper exposure. If you have the camera in spot metering mode, and when the flash tries to calculate the exposure it's pointed an a black suit, the flash is going to think the scene is darker than it really is, and it's going to overexpose. Or the opposite. Just like using an auto mode on your camera with spot metering.

You can treat your flash metering like your camera's metering. With spot metering turned on, you can use FE Lock to meter a particular part of the scene, then use FEC to increase or decrease the flash exposure. Again, I don't think most people do it this way.

Unfortunately almost all of this post is incorrect.

Although flash metering is indeed done by the camera, flash metering method doesn't depend on the camera's metering method at all.
You can set the camera to evaluative, partial, spot (if it has it) or center-weighted. Regardless of which, you can still set the flash metering to evaluative or average.

Existing light is measured with the metering method selected for the camera. Depending upon the exposure mode selected, the result may be used at any rate from not at all to 100% to determine how the image is exposed.

The flash light is then measured using the pre-flash and the metering method selected for the flash. If that's evaluative, the camera tries to figure out the proper power ratio for the flash by using some "clever" math.
If a zone in the evaluative matrix has a large difference in brightness with and without flash, then it's either very close or very reflective. E-TTL II also reads back the focus distance of the lens, and if the flash is pointing forward, this gives the camera a hint about which power ratio you reasonably need to illuminate whatever you focused on.
If there isn't much difference before and during the pre-flash, then that part of the image is probably out of reach for the flash.

When using average flash metering, no such fancy tricks can be applied. The camera will meter the pre-flash and set something that gives a reasonable exposure, on the average.

But do note that this happens regardless of whether you set the camera to evaluative or spot or whatever! Flash light will not be spot metered unless you specifically tell the camera to do that.

Which brings us into the next part, FEL (Flash Exposure Lock). If you press the */FEL button (which depends upon your camera) when the flash is on, you'll trigger the pre-flash at that instant. Now the camera will indeed spot meter the flash (or use partial mode, if spot metering isn't supported by the camera in use) and lock that flash exposure for some time (16 s for several models). If you spot meter flash on a black suit, you'll most likely overexpose the flash light in that image, unless you turn down the FEC as well.

But this, once again, is independent upon the metering the camera uses for existing light. So you don't have to turn spot metering on to do this.
As long as FEL is active (hasn't timed out) it overrules the normal E-TTL metering, so when you actually take the picture, no pre-flash will emit. You did that manually when you engaged FEL.

When combining flash and ambient light in a scene, the camera will try to reduce exposure of both somewhat in order to avoid overexposing the sum of the illumination. But that takes that both camera and flash is in an automatic mode, of course.

apersson850 wrote in post #8143757
Unfortunately almost all of this post is incorrect.

Do you have a source for your information? It goes against much of what I have been told, and I find some of the statements a little contradictory. Thanks!

Not a single source, I'm afraid. Full understanding of Canon's E-TTL system takes reading quite a lot, I've noticed, so I've studied many difference sources.

But what I wrote is supported by Canon's user's manuals for my cameras and flash guns (400D/40D & 580 EX II), by Canon's "Flash Work" guide to photography with EOS cameras combined with Speedlite flashes and by my own experience, when testing these methods I've read about and described above myself.

Try it yourself, if you have the necessary gear at hand. It will only take a few test shots to proove to yourself that the camera's metering mode doesn't affect flash metering, for example.

By the way, I now see that you also wrote that some things I posted are contradictory. It's not easy to write a post that's perfect in all ways, so please, tell me where I did wrong and I'll edit it.

When I must have my image spot on (pun intended) I use spot metering but use evaluative metering for the everyday "normal" shots.

apersson850 wrote in post #8143827
Try it yourself, if you have the necessary gear at hand. It will only take a few test shots to proove to yourself that the camera's metering mode doesn't affect flash metering, for example.

To be honest, my experience using flash doesn't really support everything you're saying, nor does much of what I have read and/or been told, particularly the point on the cameras metering mode having no effect on the flash metering. I have noticed that I get inconsistent results using spot metering mode on my camera while using the flash in ETTL. But I'm hardly an expert so I was hoping to do more research.

Fair enough. Later I'll upload four images, taken with four different metering modes on the camera, without affecting flash exposure.

Still, what is it you saw that is contradictory above, so that I can fix it? I can't find it myself.

All right, no further comment so I'll let the post above stand for now.

Here are four images, taken at the same time and place, with flash. The subject is chosen such that it should be easy for the flash to overpower the daylight on the inside of the window, but impossible outside.
Flash metering is evaluative in all images.
Camera metering is evaluative, partial, spot and average, in that order, using a 40D.

• The fact that the exposure of the daylight outside the window changes depending upon the metering method supports the idea that the camera meters ambient light according to the selected metering method, even when flash is used.
  
• The fact that the exposure of the window frame does not change with the selected metering method supports the idea that the camera's metering method does not have anything to do with flash metering, as flash metering has its own setting.

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The last two images (spot and average).

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