D700 (high??)ISO banding
This type of artifact I have not seen on D700. What I did see at ISO 6400 and above is a grid-like pattern across the very dark areas of the image. It is not common enough, however, to bother me much, but I do look for it now, after I came across it a couple of times.
|Child and seal by APenza|
from Kids world
|Calatrava in Reggio Emilia by NCV|
from Your City - Telelens in the City
|Aurora's, Science and the Milky Way by man4mopar|
from My Best Photo of the Week