Velvety Smooth Trans Focus lens
And now for something truly different: The Venus Optics Laowa 105mm f/2 Smooth Trans Focus Lens has two diaphragms, one marked in traditional f-stops and the other in T-stops. It differs from most modern lenses in its lack of mechanical and electrical connections between the camera body and lens, which means that not only is it manual focus, but the camera body and lens exchange no electronic information about aperture or focus distance settings. It even lacks automatic aperture return, the feature in most lenses that keeps the lens wide open for focusing and composing then stops down only during the actual exposure.
The metal barrel lens is made with a nicely dampened, long-throw focusing helix, and the optical formula is 11 elements in eight groups. One element is made of glass with an extra-high refractive index, three more use low-dispersion glass, and there’s also an apodization element. The apodization element serves dual purposes: to increase resolution and, in conjunction with the T-stop diaphragm, to create smooth, visually pleasing transitions between in- and out-of-focus areas (the bokeh effect). Lens performance is sharp with excellent resolution and almost no inherent chromatic or geometric distortions.
Because the lens is completely manual, and especially given its lack of an auto-aperture mechanism, it’s best used with live view on a DSLR. As an aid to dialing in sharp focus, Venus Optics uses a long-focus helix that requires a full 170-degree rotation of the focus ring to move the elements inside the lens from nearest focus—just under 3 feet—to infinity. The lens doesn’t extend or contract as it’s focused, and the 67mm filter mount doesn’t rotate. As there are no electronic connections between the lens and the camera body, no EXIF information is communicated. However, using the lens with all forms of TTL metering worked perfectly fine, including TTL flash metering.
All in all, I was impressed with this lens. It’s not for swiftly moving subjects but for portraits and setups where you have time to compose or when you can track a subject’s predetermined movement, as in filmmaking. Its results are equal to or better than many other lenses, even some far more expensive models.
The Venus Laowa 105mm f/2 Smooth Trans Focus lens comes in Nikon F, Canon EF, Sony Alpha and FE, and Pentax K mounts. It retails for $699. Adapters are available for Micro Four Thirds, Sony FE, and Fuji X mounts, which sell for $20. Venus Optics is a small Chinese company created by a group of dedicated macro photography enthusiasts, and it’s best known for unique macro lenses, including a 15mm f/4 wide-angle 1:1 macro lens that focuses from infinity to 0.185 inches and incorporates +/- 6mm of shift.
Here's why T-stops can make a big difference in your photographs.
Ellis Vener is a commercial photographer and Professional Photographer contributing editor.