Professional metering
Slower, more careful, much more accurate.
Where to find it
Viewfinder Metering Mode icon Options tab Professional metering for all modes
Summary
Forces every measurement through an extra-careful exposure pass that reads the spot accurately even when it's outside the live preview's 8-bit range. Sub-entry of CSV row 2.17 (Metering precision selector).
Detail
How it works
What it does
Every time you take a measurement, the camera does an extra-careful exposure adjustment focused on exactly the spot you tapped. For tough scenes (a bare lightbulb, the sun, deep shadows) the app then takes over and drives the sensor directly until it can read the spot accurately, going past what the camera's automatic mode can do on its own.
When to turn this on
When you need the most precise reading possible. It is especially helpful for difficult lighting like a lit lamp in a dim room, sunlit highlights, or shadow detail you want to preserve. Pair it with Single Spot mode for true zone-system metering.
What is the trade-off
Each measurement takes about half a second to a full second instead of feeling instant. If you are shooting fast and accuracy at the extremes is not critical, leave this off and the app will use its Fast mode (instant readings, but capped accuracy on very bright or very dark spots).
Recommended for
Studio work, landscape with extreme contrast, low-light interiors, any scene where you want to know the EV of a specific spot to within a third of a stop.