Repair Canon 18-55mm Zoom Lens

Welcome to Macro Photography for Beginners. I recently used precision tools to take apart my canon kit lens.

The Canon 18-55mm EF-S 1:3.5-5.6 zoom lens has become known as the standard kit lens sold with most new Canon Digital SLR cameras (with a APS-C sized sensor). The lens was originally designed specifically for the Canon 300D but has since become available as a stand alone lens. It has been equally criticized and praised by photographers during its short and illustrious lifetime. In my opinion it is an almost adequate lens with a fairly average/variable performance.

There are three reasons why I decided to dissect my Canon 18-55mm EF-S 1:3.5-5.6 zoom lens. The first reason is that the auto-focusing was "hunting" or to put it another way going backwards and forwards continuously. The second reason was to resolve a common problem with the Canon 18-55mm EF-S 1:3.5-5.6 zoom lens. I have read several accounts that suggest that this lens allows moisture to accumulate inside the casing. The moisture condenses on the inside of the glass resulting in a water mark on the glass. Images from my lens became cloudy for a large proportion of the frame. When inspecting the lens for damage it was evident that my lens had succumbed to the problem mentioned above. When looking through the lens with the naked eye it was possible to see a large water mark on the inside of the glass. The lens in all honesty was rarely used and would not be sadly missed if my attempted repair went wrong. I decided to operate on the lens and find out exactly what goes on inside a Canon 18-55mm EF-S 1:3.5-5.6 zoom lens. This post is a supplementary addition to back-up recent reports that I am probably crazier than a soup sandwich (the third reason = my own curiosity).

The first point to make about this operation is that I am fairly competent person with a good knowledge of electronics. The second point to make is that the lens was useless in its present state. I would not recommend that you dismantle a Canon 18-55mm EF-S 1:3.5-5.6 zoom lens or any other piece of electrical or photographic equipment, unless you know what you are doing or are fully prepared to lose the lens/equipment as part of the learning experience. So what is inside a standard Canon 18-55mm EF-S 1:3.5-5.6 zoom lens?

How to get Inside the Lens
First of all I wanted to investigate the problems with the auto-focus on this lens. This means delving into the electronics and most importantly find the motor inside. I’ve read a few photography forum threads about how difficult it is to get inside the lens. Let me assure you that it is not actually very difficult to get inside but once inside it is rather complex and delicate. I recommend placing the lens cap onto the lens for added protection. Then turn the lens upside down on a suitable work surface. Take off the rubber seal which is present around the centre of the reverse part of the lens. To gain entry into the lens (using precision tools) remove the two screws holding the contacts in place. It will not come apart fully with these screws in place and the soldering could be damaged if the lens casing is forced open. Then remove the four holding screws that are clearly visible around the edge of the lens casing. Carefully lift the casing away from the lens to reveal the circular circuit board underneath.

Image 1: The circular circuit board inside the Canon 18-55mm EF-S 1:3.5-5.6 zoom lens

To get further into the lens requires disconnecting the flat cables from their interfaces. These can be pulled out quit easily using the correct precision tools. They are however, not as easy to re-connect and also very delicate. If these cables are not correctly assembled (or damaged) the camera will not detect the lens and an error message will be displayed on the camera. If at this point you are still determined to go further into the lens remove the two silver-coloured holding screws.

Image 2: This is the view below the circuit board. The electronic motor can be found below the metal housing in this image.

The motor housing can also be removed and the motor examined. This requires the removal of several components that are very difficult to put back into their exact positions. In the overall image shown the electronic motor that operates the auto-focus is housed below the metal plate.

How to Remove the Water Mark
When I did manage to rebuild the lens the auto-focus was still not working. I think that there is a moral in this story somewhere. I made a tool to remove the front glass from the lens. The tool was basically a length of wood with two modified panel pins fixed through it. The pins where aligned with the two small holes on the front of the lens where it says 58mm Canon Zoom Lens EF-S 18-55mm 1:3.5-5.6 Canon Inc. The tool that I made fitted perfectly and also was designed in a way that kept it away from the glass even if it slipped (which it did several times). To remove the outer glass from the Canon 18-55mm EF-S 1:3.5-5.6 zoom lens it has to be turned anti-clockwise and it is initially very tight. It takes a lot of force to unlock the glass which gives a satisfying “crack” when it does eventually turn. When the tool I was using did slip out of position it etched unsightly marks into the plastic casing. The front glass has to be unscrewed completely from the lens casing which takes many turns. Once removed it can be easily cleaned and returned to the lens casing. I used Eclipse cleaning fluid which is designed specifically for cleaning camera equipment and dries without leaving any residue. I also used what is known to as a “magic cloth”. This is also specifically designed for cleaning camera/optical equipment and leaves no marks or dust particles on the glass surface. I used a rocket blower to ensure that no dust was left in the chamber of the lens before screwing the front glass back into the lens. This was really a very simple task.

Image 3: This is the home made tool that I used to remove the outer glass from the lens. It is crude, simple and effective (very much like myself).

In conclusion there was no real reason to take the electronic parts of the lens apart other than my own curiosity. I could not get the auto-focus to work but it was already not working properly when I started. I might re-investigate the auto-focussing problem and test the motor. In the meantime the lens can still be manually focused and after being cleaned the fog from the water mark on the glass is gone.

Image 4: The lens is now safely reassembled and it was time for one of these! No, not a hot drink (although I did obviously drink that afterwards) but a test shot to show that the lens is still in working order (minus the auto-focus). Incidentally I used my ring-flash to take this image as well! Just a quick note: The ring-flash does not fit on this lens but it can be held in place manually.

It is a very rare occasion indeed when I remove my macro lens. It is even rarer when I replace it with the Canon 18-55mm EF-S 1:3.5-5.6 zoom lens . I can still use my lens (manually) until I get around to replacing it. Well, that concludes this post which is not strictly about macro photography but more the curious nature of the macro photographer.

Marvin Africa