I think you all have made it pretty clear why not to use f number more than f16.. so the question is how do I gain very deep DOF without using so small aperture?
The solution is to do focus stack. This technique involves taking multiple shots at diff focus points, then digitally combining the shots together in PS. Can google to read more. I've been doing focus stack for macro, and it's the easiest way to achieve edge to edge sharpness without compromising on loss in detail.