Canon told me my 24-70mm f/2.8L II was beyond repair. I asked for it back and fixed it myself

Jun 30, 2016

Bimal Ramdoyal

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Canon told me my 24-70mm f/2.8L II was beyond repair. I asked for it back and fixed it myself

Jun 30, 2016

Bimal Ramdoyal

We love it when our readers get in touch with us to share their stories. This article was contributed to DIYP by a member of our community. If you would like to contribute an article, please contact us here.

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I was shooting some images of the icebergs on the black sand beach by the Jökulsárlón Glacier Lagoon, Iceland with a rental EF 24-70mm F2.8L II. Iceland is notorious for being windy, and while I was shooting there was blowing winds carrying ocean spray and water splashes all over me and my camera + lens.

Unfortunately, it seemed that sea water got into the lens either from the autofocus switch, the “weather seal”, or the extended barrel when you zoom out. After a short while, the lens stopped autofocusing and I got errors about connecting to the camera.

My worst fear happened, I could see the lens soaked with water. I was so focused on composing that I forgot to check the equipment conditions. I immediately disconnected it and let it dry. After a full day of drying, the autofocus failed but I could still use the lens on manual focus. The iris was working fine and I could take a photo no problem.

I explained my case to the shop when I returned the rental but unfortunately a few weeks later after they sent it for repairs (they send it to Canon), Canon replied back that the lens was damaged beyond repair due to sea water and nothing can be done, they will dispose of it and send it to recycling and I would have to pay the full price. I agreed as it was in my possession anyways but I asked that the lens be returned.

So I paid the full price (well luckily it had $500 off promo) and took the lens home. I didn’t really mind it as I already had plans on purchasing this lens but what bugged me was how could water damage the lens to the point where it was beyond repair.

I opened the lens and found that the parts affected were only the PCB (later I found some salt stains I the USM motor). I went on ebay and found an original new OEM PCB assembly for this lens for $36 so I grabbed it. Then I got a new USM focusing unit as well on eBay for $90, total with shipping: $140.

To my surprise I was able to fully fix it and it works perfectly fine. So I wrote this step by step visual guide on how to fix this lens for any kind of water/focusing damage or just as a general repair guide for this lens. The weather sealing is rather piss-poor, they use gaskets… but if I didn’t ask for the lens, this would have been a perfectly salvageable lens gone to recycling and I would pay full price for no lens in return. So I hope this guide will help you fix your lens one day or even show you how to replace critical components.


Step 1 (Instructions for each steps are listed below each image)


Firstly, wash your hands. Next, be calm and patient. These devices are precision devices and you need to be patient. Please ensure you have the required tools as shown above. You don’t need to desolder anything. And please for the love of photography and DIY, use magnetic screws. If one screw slips and falls inside the lens assemble, it will be a nightmare to find it. Secondly, PLEASE be very gentle and careful, if something (except Step 5 might require some strength) doesnt come out easily then you are doing something wrong, check all screws were removed or try turning the barrels to a position so it will come off. I apologize I don’t know the number for these screwdrivers, its not printed, they come from a set I had a while back. I put a Canadian 10 cent coin to show the sizes you will need.

Step 2


This is what a new autofocus unit looks like. (I forgot to take a photo of the PCB before assembling this guide but you will see it below in other pics).

Step 3


Remove the rubber ring by sliding the flat head screwdriver and pull it off.

Step 4


Remove this screw that holds the position encoder. This is hidden under some tape.

Step 5


The only part that might be fiddly, insert the screwdriver between the contact PCB and this plastic cover, then lever it up gently.

Step 6


Remove that peasant cover that uses no screws… grrrr!

Step 7


Using the smallest phillips screwdriver, remove these two tiny screws first.

Step 8


Remove the 4 screws as shown above.

Step 9


Gently lift off the metal ring, note the “weather seal” gasket will come off as well. Store safely.

Step 10


Gently lift off this plastic cover.

Step 11


This is the PCB board exposed. Don’t remove the screw yet!

Step 12


This is nightmare mode and the trickiest part, GENTLY remove these princess ribbon cables. Don’t use squeezing tools, you might break it (happened to me in the past). I use this screwdriver trick and gently pull it out perpendicular to the socket. You can use tweezers but make sure the tips are rubber coated.

Step 13


Then remove this screw. Had you removed it first, you could have damaged the princess ribbons since the whole assembly will start moving.

Step 14


Pull out this mofo gently to avoid breaking the princess ribbon cables. (fuck ribbon cables, seriously!)

Step 15


This is where the water got in… Damage is visible, it probably shorted the board’s chip. Chuck this piece away. Funny enough, I couldn’t find any other places with the salt water, maybe some stains on the USM motor, but I wonder if I really had to change that part.. (Really Canon? This is what you call beyond repairs??!)

Step 16


Once the board is removed, you will find 12 screws in a ring, remove all of them.

Step 17


Gently pull out the top cover barrel, that’s where the autofocus switch is. You might have to zoom out completely so it comes off. Leave the part with the metal dip.

Step 18


The USM autofocus unit is exposed. These two screws hold the focusing plate, remove these 2 screws and the plate and install them in the same location on your new autofocus unit.

Step 19


GENTLY pull out the USM autofocus kit. Then chuck it away. (Well, one day I will test it with the new PCB, I have a feeling this part is ok but I wanted to make this lens as new as possible so I thought I would put in a new USM motor and explore this lens for the purpose of this guide. The problem with electronics is that if the motor unit is shorted, it could short the new PCB so I took no risks and changed both.)

Step 20


Put in the new autofocus part. Please pay attention to the metal bar in the autofocus unit and make sure it is to the left-most position in its groove as shown above. When you insert it, it needs to align with the hole in the lens unit as shown above. The autofocus works by moving this bar, which once in the hole, moves the inner lens element to allow for focusing. Simple!

Step 21


This is what it will look like once you assemble the new USM autofocus unit. Take care of the princess ribbon cables.

Step 22


In case you forgot, please make sure you put the focusing plates back on, else you will have to repeat all above steps again.

Step 23


Put back the top barrel cover, the part that has the autofocus switch. Be careful of hurting the princess ribbon cables.

Step 24


Put the position encoder back in its place and don’t forget to put back the tape over it.

Step 25


BEFORE putting the princess ribbon cables back, put the screw in first, this will make sure everything is held securely first.

Step 26


Nightmare mode part 2 – Princess Ribbon insertion. Most of these cables have an extruded part behind the contacts, you can use a screwdriver tip to push each one in one side at a time or use tweezers to push both sides in at the same time.

Step 27


Put back the plastic cover, make sure the line aligns with 24mm.

Step 28


Put the “weather seal” gasket back on.

Step 29


Insert the 4 screws first before the 2 tiny ones.

Step 30


Insert the tiny screws and make sure they are securing the contact board to the metal ring.

Step Finale


Put back the peasant plastic cover and test the lens! Phew! We are done and we have a perfectly (electronically new) revived EF24-70mm f2.8L II :)


There is surprisingly very little electronics in this lens and its pretty modular. There’s the main PCB, then the USM motor unit, and then the iris (explains the lonely ribbon cable after removing the autofocus) and if my repair was to be questioned, I think it is pretty straightforward.

The lens assembly itself is very securely placed inside the lens unit and is separate as a module itself, so no, you don’t have to dismantle the lens assembly or remove any glass piece.


About the Author

Bimal Ramdoyal is a Mauritius born photographer based in Toronto, Canada.  He is a hobbyist photographer and full time software developer.  You can find out more about him on his website, and follow him on Facebook.  Also published here and used with permission.

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19 responses to “Canon told me my 24-70mm f/2.8L II was beyond repair. I asked for it back and fixed it myself”

  1. Rick Ciaburri Avatar
    Rick Ciaburri

    Canon declared one of my lenses a “near total loss” (repair estimate almost equaled the replacement cost. I had the lens repaired by a third party for less than half of Canon’s estimate.

  2. Gregg Bond Avatar
    Gregg Bond

    Nicely done, shame on Canon for deeming this “beyond repair”!

  3. Luc Primeau Avatar
    Luc Primeau

    Roger Chauvin

  4. Lars Stokholm Avatar
    Lars Stokholm

    I have had ny Olympus e-m1 out in several North Sea storm. Both camera, lens and I have been drenched in saltwater, and once I fell and got both head and camera under water for 10-15 secs. When I get home, I just clean the camera in tapwater. Canon could learn something about weatherproofing from Olympus.

  5. Roger Botting Avatar
    Roger Botting

    I used to work in a camera repair shop. Camera repair shops do not like water damage, especially salt water. Its too hard to make a repair and make it good enough that the item won’t come back as a warranty claim. So, the manufacturers and importers, as a rule, won’t touch water damage items. Its usually more time and materials than the item is worth.
    That said, we did once send a Nikon back to Nikon for water damage. Nikon refused it and one of our technicians then resurrected the camera. He had a great user camera for years after that.

  6. Richard Joseph Avatar
    Richard Joseph

    Nikon, Canon, etc – it seems – deems repairing is so 20th century.

  7. Dimos Dimaresis Avatar
    Dimos Dimaresis

    This article proves that some repair centers are just fools.

  8. Andrew Southen Avatar
    Andrew Southen

    Pretty sure that the only reason they won’t repair is that they can’t guarantee the repair due to potential corrosion issues down the track. I can see their point

    1. Mozz Avatar

      No its because theres more PROFIT in sales.

  9. Kay O. Sweaver Avatar
    Kay O. Sweaver

    Bravo on undertaking the repair yourself!

  10. Scott Waltrip Avatar
    Scott Waltrip

    Where is a 3rd party place to get a repair I have a sigma 28-70 2.8 that needs work done

  11. Trevor Olner Avatar
    Trevor Olner

    If you knew you where going to be in windy and wet conditions why didn’t you wrap your kit in clear plastic bags with an opening for the lens and viewfinder. If you use a lens hood you can secure the bag with a rubber band .

    1. storm17 Avatar

      Because he was using what Canon said was a weather sealed lens?

    2. Mozz Avatar

      Stop defending Canons HORRIBLE after sales service. FANBOY

  12. Laszlo Mag Avatar
    Laszlo Mag


  13. Martijn van Hoeflaken Avatar
    Martijn van Hoeflaken

    One word.. Pentax

  14. Paul A Avatar
    Paul A

    I dropped my Canon 70-200 F4 and it wouldn’t focus in either manual or auto. Given the lower cost of this L lens I choose not to send it in for repairs since cost of shipping and repairs might exceed a new lens so I opened it up to see if I could fix it myself. I found the sliding mechanism had gotten jammed up and I was able to release it with some effort and it works perfectly. I have no regrets and no fear for next time I might have a accident.

  15. Wes Avatar

    Of course. They would get you to let them keep it (they take it home and repair it like you did) and you are forced to buy another one. Thats how they make their money

  16. Mozz Avatar

    This sounds like something Apple would say and do. Cant wait to get away from Canon. Horrible company with the WORST after sales service.