Disassembly – Fujinon XF 18-55mm F2.8-4 OIS lens

I’ve recently read post on Fuji X forum about water damaged Fujinon XF 18-55mm F2.8-4 lens. Owner accidentally dropped it into the pond. It got submerged for seconds but water quickly entered inner areas leaving lots of dirt on glass surfaces. I’ve offered exploratory disassembly with a purpose of checking lens mechanics and try to clean accessible glass areas. Today I received that lens from Canada and partially disassembled it.

Here's the look of clean Fuji XF 8-55mm F2.8-4.

And following picture shows the look of lens after submerging it in not very clean water.

Dirt under the glass looks really bad, but fortunately lens owner did a great job disconnecting power and drying lens out for few days. I don’t see any mold or fungus yet – that is a good sign.

Disassembly steps

First step of frontal disassembly of Fujinon XF 18-55mm F2.8-4 lens is – accurately removing metal nameplate. It’s made of very thin metal so easy to deform, extra care is required.

After thin nameplate is removed, I’m unscrewing four small silver bolts. It’s a joy to disassemble using JIS screwdrivers I’ve recently ordered from Japan.

Then remove the plastic ring. You will see four black bolts and three silver calibrating bolts. Looks like this Fujinon XF 18-55mm lens sample has front lens module strongly secured with factory glue. So there is no risk of optical misalignment after reassembly. Accurately unscrew 3 silver bolts first, then unscrew all 4 black bolts.

Now slowly lift up front lens frame accurately – there are three springs on the sides that are serving for Fuji factory lens calibration. Accurately remove them. Pay attention to tiny brass nuts marked with green arrows, they may fall out, but need to be put back during assembly.

The front optical module frame contains two glass element. The dirt was on the inner glass surface of the second element, so I’ve accurately cleaned it with moisturized tissue then dried out and double cleaned with dry tissue.

If you check official Fujinon optical design, 1st and 2nd glass elements sit inside front module frame. On two pictures below you see front surface of 3rd glass element. When Fujinon XF 18-55mm lens is zoomed in/out – 2nd and 3rd element come very close at 18mm, and move far from each other at 55mm. So the space area between these two glass surfaces is collecting most of dust and dirt because air is flowing inside large space of zoom chamber.

Luckily there are no much water went inside and most surfaces from the front area are relatively clean. It’s time to clean 3rd glass surface, then assemble front area back.

If you have dirt between 1st and 2nd glass elements – module glass can be removed from the frame after unscrewing securing ring CCW (around front of 1st element) using spanner wrench. I had to do that to remove some dirt under the frame borders. 

IMPORTANT: memorize radial position of each glass element before extraction to put it back in exact place, otherwise optical alignment may shift and cause IQ degradation. I’m using red marker to add line on frame and edge of glass, so later I put glass precisely positioned (but make sure you don’t wipe out that mark during glass cleaning). I learned that trick from disassembling many other brand lens noticing that repair persons sometimes left calibrating marks on optical surface edges during their repair/cleaning. You can check how it’s done when removing front glass in Fujinon XF 100-400mm lens.

After that I’m exploring rear lens area. I’ve wiped out most dirt from the rear glass surface, what you see is just cleaning moisture. Though there is some dirt under rear element. I’m initially unscrewing three black bolts and removing plastic ring.

After that unscrewing four silver bolts and accurately removing mount ring. Then you need to unscrew three black bolts marked with red arrows and accurately pull out frame holding rear glass element.

Other glass surfaces also have noticeable water drying marks, however it’s extremely hard to proceed with further disassembly due to lots of factory glued components, so I’ve decided to stop at this point. Remaining dirt should not significantly affect optical performance, which I’ll test later.

It’s great to see that electronics is not impacted, it looks clean and I don’t see any water damage.

After re-assembly lens looks close to new.

Of course if you look through the lens on the light source – there will be some small dried water areas on the glass, but that is not affecting image details. Here’s the set of JIS screwdrivers taken on 18mm and on 55mm (100% crop of 1400px central area, noise is due to high ISO)

It’s great Fujinon XF lens, I like to see that it survived challenging water impact and all electronics works likes new – focus is quick, OIS works great, picture is sharp after optics is cleaned. Fuji engineers did a great job adding some protection preventing the water spreading too far and allowing lens to keep operating after some maintenance.

Lens test shots

Luckily it was sunny day, so I’ve took numerous shots with cleaned Fujinon XF 18-55mm F2.8-4 on Fujifilm X-E2s camera.

100% crop

100% crop of Mt Rainier shot through the office window (so far distance, atmosphere and window glass are reducing details)

The lens performs great, and it’s a joy to use XF 18-55mm zoom range.

Conclusions

This disassembly shows that it is relatively easy to clean Fujinon XF 18-55 F2.8-4 lens from the internal dust that may collect over time under front lens module (which is typical for many zoom lens). Looks like Fuji factory engineers are fine adjusting front module position first using spring loaded bolts, and after that gluing calibrating frame in secure position. It means that front module removal for cleaning does not cause optical misalignment, and I’m glad to see that.