Lens repairs

I often see two opposite cases in lens repair: the optics are in perfect condition, but something prevents the lens from working (broken autofocus, falling apart enclosure, and so on), or - everything seems to work, but the optics are in a terrible state. Today - about the second case. The Sony FE 24-105mm G OSS lens was fully submerged in some body of water, dried out, and remained functional (the aperture, stabilizer and focus all still work), but with awful stains everywhere. I'm facing a complete disassembly, splitting lens groups, massive cleaning, despair and sorrow. Disclaimer: the result of this repair is not acceptable for a demanding user. A lens that has been in water and received irreparable lens damage requires either replacing all lenses with new ones, or a one-way ticket to the trash bin. However, within the principle of "better a slightly broken high-end piece of gear than nothing at all", such a repair is acceptable.

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.

The first number that comes to mind when someone says "portrait lens" is undeniably 85mm. If you’ve got deep pockets and strong arms, you go for the f/1.4 (or even f/1.2); for less demanding photographers, there's f/1.8. Every major manufacturer offers a mass-market 85/1.8, and for example, the Canon 85mm f/1.8 USM is a true repair classic - often seen with worn optical encoders or a finicky aperture. This is our first time opening up the Sony FE 85mm f/1.8 - and we're excited to share it. So, what's wrong with it? Externally, the lens looks flawless. But it isn't always detected by the camera - the aperture value appears and disappears - and even when it is detected, it can't focus to infinity. Sounds like a simple fix, I thought. And in the end, it was. But let's do a full teardown - the inside is well worth a look.

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.

The Canon 50mm f/1.4 is arguably the most popular - and probably the most failure-prone - lens in photo history. Yes, popularity amplifies the number of complaints, but objectively, there are genuine issues. Early batches were sensitive to even minor impacts — the helicoid ring would deform, and both manual and autofocus would fail. Over time, the planetary gear system would wear out, causing annoying rattle during manual and auto focusing. The motor used has a limited lifespan and fails eventually — even without drops, water damage, or abuse. The instance I got my hands on had the first two issues combined — so let’s tear it down and fix it.

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.

I have a soft spot for the Sigma DN Art lenses. They offer great image quality, come in three versatile focal lengths (19mm, 30mm, and 60mm), and are incredibly compact. In a pancake-sized design, Sigma engineers have packed a very capable lens with excellent sharpness and pleasant rendering. I also love this series for its very common, almost charmingly typical issues. These flaws show up just slightly less often than always - and are generally very easy to fix. This time, the 19mm version (for the Panasonic/Olympus Micro 4/3 system) showed no signs of life other than some noise, and threw an error when mounted on a camera. Let's tear it down (with pleasure) and see what's going on this time.