Here is a 2-frame focus-stacked image with depth of field that is impossible to obtain with a single shot: at f/9 one is presented with two unpalatable options: either the tree is badly blurred with focus in the distance, or the tree is sharp with strongly blurred background. And it is a situation with a “deep 3D” target which does nicely with deep depth of field.
The night was still (minimal wind), so motion was not an issue. Using a 2-frame stack, the image is razor sharp near to far, everywhere and at full 36 megapixel resolution. In the full-res image, one can clearly see a diamond-shaped road sign with a symbol inside it! Now I wish that Nikon or Sony would add Pentax K1 style pixel shift at 50+ megapixels.
The best part? There was no retouching needed. Just press and go—job done with Zerene Stacker PMAX mode. There are no stacking artifacts I could find; the halos in some areas of the tree are something from the ACR conversion algorithm even for a single frame, made a little worse by sharpening—not stacking artifacts.
The Zeiss Otus lenses 'rock' for focus stacking because performance is so high; the stacking software has very high quality pixels to work with, with close to zero aberrations that could cause weird blur issues.
2 frames: 1st frame focused near the tree trunk at center, 2nd frame in far distance.