Canon EOS 70DN Basic Instruction Manual page 330

q Selecting the Metering ModeN
With q (Evaluative metering), the exposure setting will be locked when
you press the shutter button halfway and focus is achieved. In the w
(Partial metering), r (Spot metering), and e (Center-weighted
average metering) modes, the exposure is set when the photo is taken.
(Pressing the shutter button halfway does not lock the exposure.)
When <r> is set, <z> can be displayed in the viewfinder (p.376).
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w
Partial metering
Effective when the background is much brighter
than the subject due to backlighting, etc. The
metering is weighted at the center covering approx.
7.7% of the viewfinder area.
r
Spot metering
This is for metering a specific spot of the subject or
scene. The metering is weighted at the center
covering approx. 3.0% of the viewfinder area.
e
Center-weighted average metering
The metering is weighted at the center and then
averaged for the entire scene.