My new macro lens allows me to dial in whatever level of spherical aberration I might desire on a given shot. Of course, initially one tends to choose the maximum value just to get a feel for what is possible. Clearly, a lot is possible. It just strikes me as a bit odd that one of my most technically outstanding lenses can be made to be one of the worst with a small twist of a plastic ring. Mostly, I plan to leave the ring at its ‘zero’ position, but it's nice to have options, right? For most of the history of photography, lens designers have done their best to minimize optical flaws. Maybe they are getting bored. Who knows, in the future, lenses may come with multiple rings to control the various optical aberrations independently.
