Sony repair

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!

A very typical failure of a very good lens – the Sony FE 90mm F2.8 G OSS: it’s no longer detected by the camera after a fall.

This lens uses Sony’s proprietary focusing technology – Direct Drive Super Sonic Motor (aka DDSSM) – but with a twist: there are two such motors inside.

Essentially, this motor type is an ultrasonic linear actuator, first introduced in exactly this form back in the Minolta/Sony A100, where it was used to move the sensor. The lens is moved along a straight shaft via micro-deformations transmitted through a piezocrystal. The waveform is shaped (a sawtooth pulse with a sharp drop) to allow the lens to move in both directions.

And that’s where the reliability problem lies: the lens mass interacts with the motor, which is not a solid piece and is quite fragile. The motor can literally break – either at the joint between the shaft and the piezoceramic, or across the ceramic itself.

And so this well-used lens clearly ended up in for repair after a fall.