I’m going to call this feature focus stepping. The term “focus shift” is a very bad idea that damages the ability to have a discussion, since focus shift is an optical behavior caused by spherical aberration.
I just can’t conceive of how anyone at Nikon thought this terminology was appropriate—destroying well recognized optical terms by using them for a totally different purpose is an awful decision sure to muddy the waters.
Bring everything in focus for focus stacking — Focus shift photography
When shooting a landscape containing various subjects at different focus distances or creating specimen pictures of insects and flowers, photographers may want to bring everything into sharp focus.
The D850 introduces a focus shift photography function, which enables it to shoot sequences of up to 300 frames, while gradually and automatically shifting focus position from the start point to infinity.
The shutter release interval can be set from 0-30 s, while the focus step width can be selected from 10 levels. Continuous shooting at approx. 5 fps is also available. Combining the pictures using focus stacking in post-production gives you an image where every detail is in brilliantly sharp focus.
Gah! Now do I have to talk about focus shift when using focus shift (feature)? OMG what a cluster**** terminology.
That out of my system, this technology might be useful if done well. Or useless if done badly.
Why Nikon publishes blurry hardly readable screen shots in the brochure, I dunno.