EF 70-200mm f/2.8 L USM autofocus and distance indicator jump

[jcalloni33]

Hello, 

I’ve just recently purchased a new EF 70-200mm 2.8 L USM lens from mpb, and despite the site not mentioning any issues with the lens, upon its arrival I’ve had some major issues with its autofocus feature. 

When going to shoot, the distance indicator jumps rapidly up and down, and the focus in the viewfinder follows suit just as quickly. I’ve cleaned sensors, changed lighting and tried a different camera body all with the same end result. Is there an easy fix to this? Is the best course of action to send the lens back? Assuming the lens has a motor/sensor issue, what would the estimated cost and repair time look for something like this?

Thanks in advance.

[deebatman316]

@jcalloni33 welcome to the forums. Is this lens really new or is it new to you and what camera are you using it on. Is it a native EF Mount DSLR or adapted to the EOS R series. If adapted to the EOS R series what mount adapter are you using the Canon brand adapter or 3rd Party adapter. I also want to confirm that you're using the ORIGINAL non-IS F/2.8 model (EF 70-200mm F/2.8L USM lens). Not any of the newer stabilized F/2.8 models. So please confirm the exact lens model please I have pictures below on where to find the lens' full model name. The AF sensors are in the camera not lens. The lens doesn't know if the items in the shot are in focus. The camera does the focusing by engaging and disengaging the AF motor. So what sensors are you talking about that you cleaned.

[jcalloni33]

New to me, bought used but all indicators were that the lens was in excellent shape.

It’s a native EF mount DSLR as well, and yes it’s the original model not anything newer. I’m shooting it on a EOS 1Dx. All of my other lenses for the body are not having this issue. 

The sensors I cleaned were the connectivity sensors between camera body and lens, as that’s all any simple google search could suggest me doing. 

[deebatman316]

@jcalloni33 those aren't sensors those are the electrical contacts that the lens and camera use to communicate with each other. What DSLR camera are you using that lens on? Canon has released so many DSLRs over the years. So we need to know the exact camera that is being used. The EF Mount uses a completely electronic interface to communicate from lenses to the body. Can you show us a video of what the lens is doing. Where did you buy this lens?

[jcalloni33]

It’s a Canon EOS 1DX. I’ll attach a video of its behavior. I bought it off of mpb.com, I’ve used them a number of times and have yet to have an issue, all equipment I’ve purchased from there comes as the site says, until now. 

video posted on YouTube, can’t figure out how to attach to here: https://youtube.com/shorts/ejUj9ghVhek?si=oLWnJ8HTBO0bR3RV

[deebatman316]

How does the focus ring feel when you turn it. Its safe for you to turn the focus ring while in AF mode there's a clutch that prevents damage to the lens. I would return the lens back to them as the lens is malfunctioning.

[deebatman316]

@jcalloni33 try using the camera in live view to see if the lens works correctly. It may acquire focus better since it uses the image sensor for AF. Instead of dedicated AF sensors under the mirror.

[jcalloni33]

The focus ring feels completely normal as it would on any other lens, rotates freely as it should. 

There is a return policy, I was planning on utilizing it but wanted to make sure I wasn’t missing something on my end where this could be fixed. I’ll be doing that for sure now, especially if you think that’s best. I appreciate the help here!

[jcalloni33]

Same issue occurs on live view 

[deebatman316]

@jcalloni33 have you checked the focus distance switch to ensure that the entire focus range can be used. It looks like its set to 3m- Infinity instead of 1.5m- Infinity. The entire focus range isn't being used in the video. So please check that switch on your lens before sending it in for a return. It looks like that's what's what happening in the video.