Focus stacking (also known as focal plane merging and z-stacking or focus blending) is a digital image processingtechnique which combines multiple images taken at different focusdistances to give a resulting image with a greater depth of field(DOF) than any of the individual source images. Focus stacking can be used in any situation where individual images have a very shallow depth of field; macro photography and optical microscopy are two typical examples.
Such as a spider picture to demonstrate
with 8 pictures at f/11 stacked,we can get better result.
Usually，we can process focus stacking picture by Helicon focus,Zerene-Stacker , CombineZP ,Photoshop,etc.