Mark Erickson wrote:
My take:
reading when the lens is stopped down. Open aperture metering takes the
meter reading with the lens wide open. "Green-button metering" takes in
less light than open aperture metering. If you try to use "green-button
metering" in low light with a small lens aperture, you might run out of the
useful range of the meter.
Fortunately, with modern metering cells this is a scenario that almost
never happens - who does take f/11 shots in available light at 3 EV? At
such lower light levels most people shoot wider open...
On the other hand, "green-button metering"(also known as stop-down metering)
may be more accurate than open-aperture metering because it takes the meter
reading with the lens at the same aperture as will be used to actually take
Also, it isn't affected by vignetting of the lens, when using evaluative
or averaging metering mode.
Fra
