See my Zeiss DSLR lenses wish list at B&H Photo.
I’ve been experimenting with focus stacking for outdoors shots. Here the use of f/9 delivers either a blurred foreground or a blurred background. While f/13 would pull those areas in (almost), there are other overall losses (from diffraction).
So I shot a 4-frame focus stack and gave it a whirl with Zerene Stacker. In under 5 minutes, I had an image that is tack sharp for the finest grain in the wood in the extreme bottom left corner to the tiny plants in the top right.
The Zeiss Otus 28mm f/1.4 APO-Distagon makes an outstanding lens for focus stacking, due to exceptional correction for color aberrations and ultra high sharpness. See my in-depth review of the Zeiss Otus 28mm f/1.4 Distagon as well as my article on it, at Zeiss Lenspire.