3D pop, který se nedá koupit nový: objektivy Contax Zeiss

Smooth transitions The gradual falloff of the focus plane, a specific characteristic that differs from modern lenses, is one of the reasons that would give you the feeling there is something different about this picture, that it looks more alive and real somehow. 3D pop also isn't the same thing as shallow depth of field, which is where a lot of the confusion comes from. Marko Li, a filmmaker who writes about image quality on his Clever Ghost blog, makes the point in his long essay What is Image Quality, Really?: if dimensionality were just background blur, images would never look dimensional at f/8. They do. Most of my own footage is shot between f/2.8 and f/5.6 with plenty of the room still readable behind the subject, and the Contax lenses still make the person stand out from it. The separation comes from how the lens draws the subject, not from how hard it erases everything else.

Modern lenses aren't short on sharpness. Most current glass from Sony, Sigma or Fujifilm is corrected to a clinical degree, and at shallow depth of field it gives me what I think of as the green-screen look: the person looks pasted onto a blurry photo of the room, as if the two were taken on different days. The subject is sharp, the background is soft, and nothing connects the two. Li describes the same effect from his own comparisons. Lenses from Fujifilm, Sigma and Sony, he writes, can be as sharp as Zeiss "while somehow not looking as dimensional", looking "like a cut-out".

Part of the explanation is in how a lens draws the transition between a focused and an out of focus area. Stefan Ballmann of Zeiss research explains that lenses with spherical overcorrection tend to show a harsher transition from sharp to blurred areas, and that hard edges in that transition are often seen as artificial. That abrupt cliff between the sharp plane and everything behind it is exactly what reads as a green screen. With the Zeiss lenses the fall-off is gradual. The eye travels from the eyes to the ears, to the shoulders, to the room, and each plane is only a little softer than the one before, which to me is much closer to how a person actually looks standing in a room.

An objectively subjective chart MTF charts, which many photographers focus on to compare lenses, can you tell about a few aspects of the lens. But it suggests a complete and objective picture that in reality is omitting a lot of other data that is just as relevant. None of this shows up well on a chart, which is why the internet keeps arguing about whether 3D pop exists at all. An MTF chart measures contrast at a few spatial frequencies across the frame. It says nothing about how a face sits in a room or how the focus rolls off behind it. When Chambers kept pressing Hubert Nasse, who wrote Zeiss's reference papers on reading MTF curves, on what makes a lens perform well, Nasse answered, "it is the sum of everything": no single measurement tells you. Ballmann says no set of measurements can be "a proper substitute for the visual impression of a photograph taken under realistic conditions." Zeiss's T* anti-reflection coating plays a supporting part in that sum. The micro contrast comes from the optical design, and the coating keeps stray light from greying it out. No chart will settle that argument, but my own eyes settled it for me years ago.

For old lenses, the Contax Zeiss look remarkably un-vintage. There is no mushy softness wide open, no halos around highlights, and no swirly or busy bokeh competing with the subject for attention. Nick Morrison, whose Contax Zeiss Survival Guide on the REDUSER forum is still the reference text for people shooting these lenses on video, put it well: "The Contax don't look vintage to me, but they also don't look modern." That balance is what makes them usable on client work. A client wants their event to look beautiful and couldn't care less which decade the glass comes from, so an old lens with a heavy vintage signature is a risk I'd be taking on their behalf.

They are built like instruments, with all-metal barrels and a mechanical feel that no modern lens in my bag comes close to. All of mine are MMG or MMJ copies, the later versions made in Germany and Japan, and they date from around the nineties. After thirty years, not everything moves the way it did when it left the factory. Some focus rings are a little stiff, usually from old lubricant, and a few lenses have other small issues, which is fair for equipment of that age. So I've started taking them apart and servicing them myself. It's slow work with small screws and old grease, but there's no better way to see how well these lenses were made. With one of them in pieces on the desk, what surprises me is how little room the mechanics are allowed to take. Everything is engineered around the glass, giving it as much space as possible without costing the focus any of its smoothness, and the whole thing is built so sturdily that a knock against a door frame is nothing I'd worry about.