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— Winston Churchill
|Short Take: Sony NEX Wideangle Adapter VCL-ECU1|
Some radially symmetrical objects make orientation difficult.
Updated: August 7, 2011. In the 1970s and 1980s, an "add-on lens" was anathema; these were the types of things that shade Brooklyn camera dealers sold in "kits" with SLR cameras and 50mm lenses. The lenses had a justifiable reputation for being bad; they were typically designed and built by no-name Japanese or Taiwanese makers, they were not optimized to any particular prime lens, and they had large front elements that attracted flare. Come to think of it, it is difficult to think of a system that had supplemental lenses or interchangeable elements where the performance was equal in all permutations. Consider the Canon EX, the Retina IIc/IIIc series, the Nikkorex, the convertible large format lenses like the Symmar.
The inquiry into the Sony VCL-ECU1, a 0.75x converter for the NEX 16mm lens, began when I saw a number of people using (sometimes expensive) adapters to plug the (always expensive) Cosina Voigtlander 12mm lens into a NEX body. This would mean zone focusing (often with the scale being thrown off due to adapters that are intentionally short to guarantee infinity focus); a significant loss of exposure automation; and dimmer, slower ECF viewing. So when the Sony units started showing up on Amazon at $90, the real question became: how bad could it be?
The answer, somewhat surprising to people who are quick to dismiss, is "quite good." The initial observation is that a system consisting of a lens plus its add-on is limited by the weakest link. Here, where the host lens has known shortcomings, you can see that the VCL-ECU1 is actually degrading things very little.
If you set the camera to f/5.6, you now have a direct basis from which to compare the VCL-ECU1 to a 12mm rangefinder lens. This part is missing from reviews; people like to compare supplemental lenses wide open (here at f/2.8) to prime lenses that are two stops slower. Sony can't build a 12mm system that performs optically perfectly at f/2.8 - but neither can Cosina. So let's go in order:
1. Mounting and handling. The Sony unit bayonets onto the front of the 16mm lens; it is has a sliding safety catch to prevent accidental disconnection. The lens is the same diameter as the 16mm lens, has a nice quasi-metal finish, and sports a hard-rubber petal hood. Overall, it's roughly the same size as the NEX with the 18-55mm lens mounted. It balances ok.
2. Focusing. This attachment brings the minimum focusing distance down to 8 inches. Not that you would want to get that close with a non-macro lens... focusing is, as you can imagine, lightning-fast, with face detection and all of the other AF modes intact.
3. Sharpness. At f/5.6 (which is likely the aperture you'll want to use; bigger means more astigamatism; smalller means diffraction), the central 16x16mm portion of the sensor is very, very sharp - and the sheer amount of moire/aliasing you get indicates that the system is outperforming the sensor (you might mistake this for chromatic aberration - which is discussed separately below). When you get to the last 2-3mm of the diagonal, the sharpness falls off fast. Whether this is due to field curvature or simply not enough "grunt," it is unclear. Consider whether the extreme corners of 18mm-equivalent images are ever significant to composition. Likely answer: no.
4. Vignetting. This was something that people seemed to think would be terrible (clearly, people who have never used a lens shorter than 20mm on a 35mm camera). At f/5.6 (again, the benchmark aperture), flare is almost imperceptible, and when you turn on profile correction in Lightroom, it disappears completely (apparently the vignetting after mounting the adapter is essentially the same as before - which allows Lightroom to correct it out).
5. Flare. Flare is pretty well controlled. The unit has a built-in petal hood. Sometimes, if the sidelight hits just right, you can get a purple splotch like this (see lower left-hand corner). Again, not the "horrible toy plastic lens" that detractors love to attack (by the way, this one is all glass).
Even the worst case, sun in frame, gives you this:
6. Bottom Line. What can you say about this item other than that it is cheap, functional, and fun? No, it's not going to have the quality of an expensive, adapted 12mm lens for a 35mm rangefinder , but for the limited use that very wide lenses get, it is more than up to the task for most people.