recompose with flash question, and flash metering Q

[Scott6]

From the flash Bible

Do not focus and recompose with flash. The fact that the camera biases flash exposure to the nearest focus point, if the camera has multiple focus points, is important to keep in mind. If you’re in the habit of using the old “focus, lock AE and recompose image” technique, be sure not do this when taking flash photos.
Flash metering occurs after ambient light metering, so in this case you’re locking AE but not flash metering, and therefore recomposing messes up your flash metering. Instead, select the focus point that’s closest to your subject in order to bias flash exposure to that area.
There are two exceptions to this rule, however. First there are type A bodies which support FEL (http://photonotes.org/articles/eos-flash/index3.html#fel). You can use FEL in such situations to lock flash exposure to a given area of your photo before recomposing. Second, cameras with support for E-TTL II are supposedly less vulnerable to this problem because they can include distance data in flash metering.


Dose setting the camera from multi AF points to only one AF point affect the flash metering that happens before and after the cameras ambient light metering? What im think im trying to ask is, dose the flash meter to the AF point in use? So for me im almost %99 of the time using center only

[Curtis N]

That info is a little dated. The original E-TTL system emphasized the active AF point, but E-TTL II does not.

E-TTL II was introduced with the EOS 1D Mark II and is the system on all EOS digital cameras produced in the last couple years.

[acutshall]

considering the question above:

I use center focus, press the shutter half way to lock exposure/focus and recompose; If I use this method when using ETTL is the flash going to use my original subject exposure settings or is it going to recalculate with a preflash?


The reason for asking is that when I take a picture of 2 subjects standing apart I will put my center focus point on the face of one and recompose , that now puts my center point between the subjects pointing out into oblivion, I do not want my flash exposing for that. The FEL does not work for me, I have to take my finger of the shutter button to reach it and that cancels out any camera/focus I have already done.
Thanks

[Hangerhead]

well, why not focus... then use the '*' button whilst still keeping the centre focus point on the subject, then recompose.
is that not going to work?

[acutshall]

well, why not focus... then use the '*' button whilst still keeping the centre focus point on the subject, then recompose.
is that not going to work?

that will lock camera exposure, will it also lock in Flash exposure as well?

[Curtis N]

Flash exposure with E-TTL is determined when the pre-flash fires. If you use the FEL button, it happens then. Otherwise, it happens when you depress the shutter button completely.

[PacAce]

that will lock camera exposure, will it also lock in Flash exposure as well?

If it's not very evident from Curtis' reply, the 1D series cameras have a button (the "*" button) for AEL and a separate button ("FEL" button) for FEL.