Over the last 150 years I have noticed that we are always entering a new era, an era in which a new generation of lens technology finally allows us to take the pictures we have always longed to take.
First we had optical formulae, lens with multiple elements that allowed ludicrous speeds like f/4.0, which freed us from the tyranny of poor lenses.
Later, new glass formulations appeared, allowing for better lens corrections or something, and we were liberated at last from the dank prison of poor lenses.
Coatings and more glass came, freeing us all over again.
Computers arrived, and people started using them for lens design which, I dare say you will not be surprised to learn, unshackled our chains and set us free to fly the heights of fancy.
And now we're starting to see crazy nanotech dffusion.. things. That have negative refractive indices, I think, whatever that means. And I am absolutely certain these will finally enable a good lens, a lens worthy of our vision, to be delivered.
I submit to you this only slightly hyperbolic assertion: There are no bad lenses, only bad photographers.
Unpacked slightly, there are no bad lenses, only lenses in the hands of photographers unable to make sense of the properties of the lens and to put them to good use.
In this same era of 40 pound computer designed lenses with almost no chromatic aberration, we have plastic lenses, we have deliberately uncorrected lenses. We have exotica like the Cooke PS945. We have people running kickstarters to to build Petzval lenses. Lest you think it's just hipsters and idiots, I direct you again to the Cooke PS945, which is emphatically not a lens for hipsters. This is a lens for the very very very serious photographer indeed, and if you lent one to Ming Thein without mentioning to him the price, he would surely find much negative to say about it.
The point is that every lens can be made to do something interesting and good. It might not be something you particularly want to do, in which case you should get a different lens or two. We are not in an awesome new era in which finally lenses allow us creative freedom. We're in the same old era in which manufacturers continue to build new lens designs with new lists of specifications, which they then market vigorously.
These new lenses also have a place in the world. The can render an image upside down on on a flat surface too, with some properties, which properties can perhaps be bent to the whim of the photographer.
Having been raised in the same school as most of you, the school of More Sharpness and Less Aberration, I feel the tug of the Otus. But I resist, because it turns out those are not the pictures I want to make. (And even if they were, I know how to make them much more cheaply.)