R5 Mark II + "Detect priority AE while AF"

[thegios]

Apologies, I've tried asking this before, but haven't got a clear answer yet, so I'll try asking again...

Part 1

Is it true or not that Evaluative Metering considers the whole scene but with a bias on focusing point? I am asking because this is not documented on Canon manuals but many photographers say so. This is also supported by Canon manual (thanks Canon for making things ambiguous) in the AE Lock description: in Evaluative Metering the AE Lock considers the point in focus.

Part 2

If we all agree that Evaluative Metering is biased on point in focus , then what is "Detect priority AE while AF" for? This is a new option introduced with R5Mk2 and works only under two concurrent conditions: Evaluative Metering + a SUBJECT is in focus, where subject is a person, an animal or a vehicle. SUBJECT is key here, because for "Detect priority AE while AF" a chair in focus or a house in focus or a tree in focus is not a SUBJECT.

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So, given we are in Evaluative Metering, I'll try to give my interpretation of three possible scenarios, based on some tests:

1. "Detect priority AE while AF" is OFF: metering considers whole area with a bias on point in focus.

2a "Detect priority AE while AF" is ON + no SUBJECT in focus: same as 1 (metering considers whole area with a bias on point in focus.)

2b. "Detect priority AE while AF" is ON + SUBJECT in focus: metering considers ONLY THE SUBJECT, not the whole area with a bias on the SUBJECT but ONLY THE SUBJECT, that is a sort of spot metering on the SUBJECT in focus.

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What do you think?

[p4pictures]

I have a slight different interpretation, but either yours or mine could be correct.

>> Evaluative + Detect priority AE while AF off: the whole area is considered, but only the active AF point - possibly the subjects eyes is used to bias the AF

> > Evaluative + Detect priority AE while AF on: the whole area is considered with a bias on the detected subject so this includes the whole of the face / person not just the AF pt. 

This could then account for the much closer f/6.3 and f/4 aperture values you saw in the two shots Bw and Bb since your subject is consistent then the exposure is less impacted by the change of background as the camera is biasing the exposure for the whole detected subject not just the AF point. Potentially this would be affected by the size of the detected subject in the frame.

[Waddizzle]

Totally agree, Brian