Nikon D3300 Reference Manual page 311

A
Identifying CPU and Type G, E, and D Lenses
CPU lenses can be identified by the presence of CPU contacts, type G,
E, and D lenses by a letter on the lens barrel. Type G and E lenses are
not equipped with a lens aperture ring.
CPU contacts
CPU lens
When using a CPU lens equipped with an aperture ring, lock the
aperture ring at the minimum aperture (highest f-number).
A
Matrix Metering
For matrix metering, the camera uses a 420-pixel RGB sensor to set
exposure according to tone distribution, color, composition, and, with
type G, E, or D lenses, distance information (3D color matrix metering
II; with other CPU lenses, the camera uses color matrix metering II;
which does not include 3D distance information).
Type G or E lens
Aperture ring
Type D lens
Technical Notes 291