Nikon D810 User Manual page 449

D
AF-Assist Illumination
Some lenses may block the illuminator at certain focus distances.
Remove lens hoods when using the illuminator. More information on
lenses that can be used with the AF-assist illuminator may be found on
page 494.
A
The Built-in Flash
The built-in flash can be used with CPU lenses with focal lengths of
24 mm (16 mm in DX format) to 300 mm, although in some cases the
flash may be unable to entirely light the subject at some ranges or
focal lengths due to shadows cast by the lens, while lenses that block
the subject's view of the red-eye reduction lamp may interfere with
red-eye reduction. Remove lens hoods to prevent shadows. The flash
has a minimum range of 0.6 m (2 ft) and can not be used in the macro
range of macro zoom lenses. The following illustrations show the
effect of vignetting caused by shadows cast by the lens when the flash
is used.
Shadow
More information on lenses that can be used with the built-in flash
may be found on page 494.
Vignetting
425