Ultrasonic motor

Variations in the final product are nothing unusual. In mass production, reliability gets refined, costs are optimized (though sometimes one comes at the expense of the other), and engineers make small tweaks to the design along the way. I can name several pieces of photographic gear where identical external appearance hides very different internals. But this time, Sony has outdone everyone — two completely different lenses hiding under the exact same nameplate! That’s a bit of a spoiler, of course - I only reached this surprising conclusion after fully tearing the lens down for repair, screw by screw. Before that, I was absolutely certain I was about to face the same kind of job as in my earlier post about the Zeiss 50mm 1.4 ZA. I had seen a colleague's video clearly showing a regular ring-type AF motor inside. But - let's start at the beginning. The Distagon T* FE 35mm F1.4 ZA arrived with a "camera doesn't recognize the lens" complaint, although it did show some signs of life - the aperture would open and close when mounted. For modern lenses with fully electronically controlled focus and aperture (true for Sony and many others, but not for old EOS, for example), the camera runs a quick self-test at startup. It checks the focus mechanism, the aperture, and - if present - the optical stabilizer. The focusing group moves to near-infinity, the aperture first fully closes then fully opens, and the stabilizer lens moves to the center position. If any of these tests fail, the camera refuses to recognize the lens. It's not a very fair to customer - if the focus motor fails, you can't even use the lens manually. But that's how modern designs work: with no direct mechanical connection between the focus ring and the optics, manufacturers see no point in leaving partial functionality. Knowing this lens has no optical stabilizer and that the aperture was behaving normally, I went straight to the focus motor, expecting to find a seized ring-type motor.

Fast autofocus lenses from the South Korean company Samyang are extremely interesting and slightly underrated. The company has journeyed from fully manual budget lenses to fully compatible autofocus models, and they've succeeded. Modern AF lenses don't just have autofocus; they're equipped with “trendy” ultrasonic motors of their own design. Considering the excellent image quality, I'd place them alongside both branded primes and general-purpose zooms. Of course, there's a bit of hardware "tar" in the honey: reliability isn't quite their strength yet. Judge for yourself - common failures include: Ultrasonic motor failures Stuck apertures Splitting in half at the lens mount However, other issues are very rare, and the ones that do occur are usually easy to fix successfully. Below is a full repair report based on working with five (!) identical Samyang AF 35/1.4 FE lenses - all apperaed for service at the same time.

Among Sony E-mount lenses, the G Master and Zeiss (ZA) series stand out in particular. The G series is supposed to deliver mind-blowing image quality, fast autofocus, and record-breaking aperture speed, while the ZA line, in turn, focuses on artistic rendering (allegedly) - and fair enough, Carl Zeiss engineers did lend a hand in designing the optics! I'll leave this kind of classification to the marketing department, but from my own experience, there's nothing alien about Zeiss-branded lenses. They're still standard Sony system lenses, instantly recognizable once you take a look inside. But the lens I'm dealing with here is an absolute beast - the Planar T FE 50mm F1.4 ZA*. Compared to other system 50mm f/1.4 lenses, it impresses right away with its size and weight. I've rarely held a 50mm lens this massive - maybe just the Sigma 50mm 1.4 Art comes close in terms of weight. The image quality is also seriously impressive - razor sharp wide open, with a pleasing bokeh. I don't have the words to describe its character - I fix cameras, I don't shoot with them. After disassembly, though, my jaw dropped. This thing is engineered like money was no object. But back to why it's on my workbench. The issue isn't typical - focus is jumpy and unstable, often overshooting the sharpest point. In manual focus mode, even the slightest turn of the ring sends the focus flying from one extreme to the other. And the motor makes a whining noise when powering down. Let's dive into the teardown and see what's going on!