Tech

Lensbaby Twist 60: Into the Future/Past

6.16.2016

Lensbaby Twist 60: Into the Future/Past

Lensbaby recently released a very different lens, one with its roots in the very beginnings of photography and a 19th century design by Joseph Petzval—the Twist 60.

Historic Background: Joseph Petzval and Lensbaby

© Ellis Vener

The first thing you notice when shooting with the Twist 60 is that it can be a bit hard to focus accurately when using a DSLR viewfinder. Focusing precisely is best done using live view or tethered to a computer. From f/2.5 to f/5.6, the center of the image is sharp with a rapid falloff of brightness and sharpness coupled with the telltale concentrically smeared distortion. Beyond f/5.6, evenness of exposure from center to edges is better but you also start to lose the lovely softness and distinct swirly bokeh. With smaller than full-frame format cameras you are using only the center “good” area of the image circle and won’t see much of the effect.

Although it’s clearly not a do-everything lens, the Twist 60 is great for making portraits with a nostalgic romantic mood. What I like about the visual effect is the ways the sharp center and radially blurred area outside of that work together to distinguish a subject from its surroundings. The effect works best when there is a good deal of distance between the subject and the background and the out of focus area is a broken up pattern of light and dark areas. The same kind of light patterning can make an effective foreground as well but is harder to accomplish when photographing a portrait.

This brings up something obvious but to be mindful of: the sharp spot is in the center of the lens and this makes it harder to create images where you want an asymmetric composition. During my initial forays using the Twist 60 I immediately started wishing for two things: a longer focal length version and a simple shift mount. The longer focal length would do an even better job of separating the subject from the background or foreground, and a shift mount would open up compositional possibilities without needing to crop during processing. Another thing worth noting is that the lens is completely manual and the mount has no electrical contacts, though this posed no problems getting accurate exposures in aperture apriority or manual modes, even when using E-TTL controlled flash. 

There are two parts to the Twist 60: a focusing mount and the lens itself, which can be mounted in Lensbaby’s ball joint-like Composer Pro. The Lensbaby Twist 60 in a standard focusing mount sells for $279.95 for Canon EF, Nikon F, or Sony-E mount. If you already own a Lensbaby Composer mount, the Twist 60 optic by itself goes for $179.95.

Historic Background: Petzval and Lensbaby

Joseph Petzval was a 19th century Hungary-born mathematician and physicist, who as a student and then professor in Vienna helped create the field of geometric optics. Geometric optics starts with a mathematical model of light in which it travels in a straight line—a ray—which bends and in some cases splits as it crosses the boundary of two different media such as the boundary between air and glass, between water and glass, or even between two different types of glass), and can follow a curved path as it travels through a single medium in which the refractive index changes. In the early 1840s Professor Petzval used these principles to create the first large aperture, high-resolution (for its day) camera lens, a simple design using just four elements in three groups: a doublet in front of the aperture and two air-gapped elements behind it. For portraitists in the years before artificial light, this reduced the time a client needed to sit perfectly still from minutes to mere seconds.

The decades-long heyday of Petzval lenses passed into yesteryear’s, and for several decades the Petzval design was superseded by more modern designs that do a far better job of correcting optical flaws by using more complex optical paths that also add size and weight. Like all Petzval design lenses, the Lensbaby Twist 60 is a simple design: four elements in three groups with an adjustable aperture between the first group—a doublet—and the third element. Compare that to a modern lens like the Zeiss OTUS 50mm f/1.4, which has 12 elements in 10 groups, or the Sigma 50mm DG HSM A with 13 elements in 8 groups, or even a humble Canon EF 50mm f/1.8 II, which utilizes just 6 elements in 5 groups. The goal of the complex designs used by modern lenses has one purpose: to essentially make the lens invisible by increasing resolution and reducing optical distortions to near zero. 

The modern rebirth of the Petzval Portrait lens began in 2014 with the Lomography New Petzval 85 and now this version from Lensbaby. It is a classic case of how to make old technology popular again with a digital twist. While the Lomography 85mm Petzval looks like a retro-techno steampunk relic, the Lensbaby version is smaller and lighter and relies on plastic rather than brass, giving the Twist 60 a cheaper point of entry. 

Today the principles of geometric optics form the foundation of modern lens design, but sadly Professor Petzval ended his days in a pauper’s grave after a bitter legal battle with a German competitor, Voigtlander, that ended only after Petzval’s intellectual property and papers were destroyed during a mysterious home break-in. Afterward, his Austrian patents were copied by foreign manufacturers who never paid him the royalties he was due. 

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