Showing results for 
Show  only  | Search instead for 
Did you mean: 

Canon EF 24 70 F2.8 manual focus slip

Rising Star

I want to share with you guys here a small project I have done to repair my 24 70 F2.8 (version I) which has a problem focusing manually. When I rotate the focus ring in manual mode, the ring slip at certain points and cannot achieve focusing. Auto focus is fine. So I ordered a set of JIS screwdriver and opened up the lens to check it out.


I discovered that the silver retaining ring of the USM unit was not engaged thus the pressure required to control the USM system has lost and have to be adjusted. I screwed the retaining ring back in, added a few drop of loctite (blue) to fix it in position. Put everything back and it's working okay now.


Since I have not dismantled the Helicoid and the other glass elements, accuracy of focus is not affected. Do not attempt to DIY like I did. You risk sending it back to camera repair shop and pay $300 or more to make it work again.20160224_131704.jpg20160224_132410.jpg20160224_134321.jpg20160224_134348.jpg20160224_202655.jpg



I like the cardboard tray to catch loose parts. 


I have repaired countless pieces of electronics over the last 40 years, and losing a screw, a nut, a washer, a jumper, a harness, or a widget can drive you nuts.  However, I have learned one trick over the years when I lose track of something under those conditions.


Don't get up.  Stay seated.  Remind yourself of this, "It is within arm's reach."  It works 90% of the time.

"The right mouse button is your friend."

The tray is good but I still lost a tiny spring in the AF module of a 18 55mm kit lens. It just disappeared.


I have some tapes (green) to organize the screws and small parts. Just to make sure that they won't go to the wrong place.

I just performed this repair and wanted to add a couple things that might be helpful to anyone else looking to do the same.


The silver metal retaining ring that allows manual focus to engage will have some blue adhesive on it already. In my case, it was dried up and not sticky anymore (probably why I was having this issue). Now, to get the silver ring to engage properly, it needs to be tightened just slightly. You'll notice some little indentations around the outside edge of the ring. Carefully use a flat-head screwdriver in one of the indentations to turn the silver retaining ring clockwise while gripping the body of the lens. I moved mine a matter of degrees and it's no longer getting stuck at infinity. After moving mine I wiped a little adhesive where the ring is held in place.


Note you don't need to remove the entire USM assembly to do this, just get past the PCB and the zoom ring assembly and you'll have access to this ring.

01/18/2023: New firmware version 1.1.1 is available for EOS R6 Mark II
01/09/2023: Help ensure your autofocus is properly aligned with a Canon Precision Alignment
01/03/2023: Welcome to CES 2023!
12/08/2022: New firmware version is available for EOS C70
12/07/2022: New firmware version 1.7.0 is available for EOS R5
12/07/2022: New firmware version 1.7.0 is available for EOS R6
11/22/2022: New firmware available for EOS R3, EOS R7 and EOS R10
11/16/2022: We're thrilled to be ranked among the Best Employers for Veterans in 2022 by Forbes.
08/31/2022: New firmware version 1.1.1 is available for RF 70-200mm L IS USM
08/09/2022: New firmware version 1.2.0 is available for CR-N 300
08/09/2022: New firmware version 1.2.0 is available for CR-N 500
07/14/2022: New firmware version 1.0.1 is available for CR-X300
06/10/2022: Service Notice:UPDATE: Canon Inkjet Printer continuous reboot loop or powering down
06/07/2022: New firmware version 1.3.2 is available for PowerShot G7 X Mark III
05/31/2022: Did someone SAY Badges?
05/26/2022: New firmware version is available for EOS-C500 Mark II
05/26/2022: New firmware version is available for EOS-C300 Mark III
05/10/2022: Keep your Canon gear in optimal condition with a Canon Maintenance Service
05/05/2022: We are excited to announce that we have refreshed the ranking scale within the community!
04/26/2022: New firmware version is available for EOS R5 C
03/23/2022: New firmware version is available for EOS-C70
02/09/2022: Share Your Photos is back!
02/07/2022: New firmware version 1.6.1 is available for EOS-1DX Mark III
01/13/2022: Community Update. We will be retiring the legacy profile avatars on 01/20/2022. Click this link to read more.