An Update on My Canon 24-105mm F4L Problem
I wrote a while ago about the issues I was having with my Canon RF24-105mm F4L. I noted that for some bizarre reason, the lens got softer at 24mm as you stopped down from f4. This is the opposite of what normally happens with a lens. I went through significant testing to make sure I wasn’t doing something stupid and to try to identify the problem. I also contacted Canon, and they said this was not normal behaviour and that I should send it in for service, as it was still under warranty. So I did that, and last week, after it took a month, I got the lens back. The results, unfortunately, were disappointing.
Before I get to that, a few other odd things showed up during my testing. First of all, it seems to be related to autofocus, as the issue doesn’t occur when you shoot manually. Also, you can prevent it by moving the focus point to the edge of the frame. So clearly, something weird is going on. Also, the reported focus distance changes when you stop the lens down, although this apparently is normal. The other problem is that at 105mm at f/4, focus tends to be a few mm in front of the object you’re focusing on. None of these problems occurs with my other 24-105mm lens, the STM version, but that’s a much poorer-quality lens.
So anyway, I sent the lens to Canon, which is kind of a ridiculous procedure. Because they have consolidated all their European warranty repairs under one roof, it has to go to Germany for service. This is all done through a web app on their site, but I had issues with it, as it’s a bit buggy. They pay for shipping, so that’s good, but it took a week to get there, and then it spent another week in the warehouse waiting for someone to look at it. In fairness, you could track this the whole time, so there’s that. Eventually, it moved to their workshop, where it was for less than 30 minutes before the tracking showed it on the way back to me. So, at this point, I wasn’t optimistic.
After another week, I got it back, and the service note said that they couldn’t find a fault with it. The thing is, I’m not sure they even checked properly. I had supplied detailed notes, and part of that was that the issue is not a manual focus issue, but the lens was set to manual focus. I had also sent sample files that were never opened (I used Dropbox to send them). I suspect they used some automated test rig and did a quick check based on the summary without actually reading the notes. I’m extremely disappointed in Canon's service because there’s clearly an issue here, and Canon’s own technical support person agreed with me.
Anyway, I’m left with a conundrum now. It’s such a weird, specific problem. I can work around it, but it’s not ideal. I could sell the lens and get another one, but there’s no way to know if that will be the same. The other thing that occurred to me is that it could be the camera. There was a video a while ago from Peta Pixel where they were reviewing a Canon lens and noticed excessive edge softness, and in the end, it turned out to be a misaligned sensor mount. So it could well be that.
So I’m going to try to either rent or borrow a different body to see if the lens performs the same on it. If it does, then I know it’s the lens and can just get a new one. If it’s not, then I’m going to have to look at either trying to get my body repaired or just replace it. I don’t have much confidence in Canon’s service centre now, so we’ll see what happens.
The thing that annoys me the most is that this would be a great lens if it worked. It’s super sharp apart from these issues, and the micro-contrast and colour are fantastic on it. At about 35mm to around 90 mm, it’s perfect. I downloaded samples online and can’t see any evidence of this issue, so it’s either mine or there is a problem with the camera. And it takes so long to get sorted. I bought this lens before Christmas. It’s partially my own fault as I didn’t get to test it straight away. But I also regret buying it from Amazon, as it would be easier if I could just bring it back to the dealer.
To be honest, I’m a bit disappointed with the whole affair, and I’m considering just getting rid of it and moving back to Nikon, or even Sony or Panasonic at this stage. But that’s a whole lot of pain, and I’m not really in the position to do it right now, so for the moment it’s a matter of trying to solve it or work around it until I can.
As before, if anyone has any insight or has ever come across anything similar, please let me know.