What is the full focus shooting method? How to realize D90?

I heard this word for the first time 1. I don't know who created it, but literally, it means that all objects are in focus.

This probably refers to two fields: hyperfocal distance and depth of field synthesis.

Hyperfocal distance is a word in the movie era, and most of them don't refer to it.

So it should refer to depth of field synthesis. The result of depth of field synthesis is to make the whole object in focus range (full focus). Depth of field synthesis is mainly used for macro photography. Because the macro depth of field is very shallow, only 2-3 mm, and the thickness of insects is only 2-3 mm, in order to pursue the ultimate details, it is necessary to take a number of pictures with different focuses, and then synthesize them to make the depth of field larger and make the whole insect within the focus range.

For example, 1 photo, the focus is on the insect eyeball, and the clear range is only 2-3 mm before and after the eyeball. The second photo, the focus moves back a little, and the third photo moves back ... If the insect is 3 cm thick, it takes about 10 photos to make the whole insect clear, which should be full focus. This method is also commonly used in jewelry photography.

This method has nothing to do with d90. All cameras are universal.