Nikon D780 DSLR Camera (Body Only) - Manual (Page 396)

350 Other Shooting Options
• Specifying both the focal length and maximum aperture
of the lens
:
- Enables color matrix metering (note that it may be necessary
to use [ Center-weighted metering ] or [ Spot metering ] to
achieve accurate results with some lenses, including Reflex-
NIKKOR lenses)
- Improves the precision of [ Center-weighted metering ] and
[ Spot metering ] and i-TTL flash control
D Teleconverters and Zoom Lenses
• If the correct focal length is not available, for example because you are
using a teleconverter or zoom lens, choose the next largest value.
• The maximum aperture for teleconverters is the combined maximum
aperture of the teleconverter and the lens.