I wrote a blog post a long time ago about one of my biggest regrets, photographically speaking. This was the fact that I sold my Canon 5D Mark II and 24-105f4L lens. I always loved that lens, and I really regretted selling it. As I had moved on from Canon at the time, I never went and re-purchased it. But, for the past two years now, my main camera has been a Canon R6II and for the most part, I’ve been loving it. However, I had only been using the kit lens that came with it, the 24-105 F4-7.1. Which is a fine lens in its own right. But still, I longed for my old friend, or at least the updated version. Finally, a couple of months ago, in a sale, I was finally able to get the RF24-105 f/4 L. Unfortunately my reunion wasn’t as happy as I had hoped. In the end, I was quite disappointed, but there is a twist in the tale here.

Image taken with the 24-105 f/4 L (24mm at f/4)

I got the 24-105 F/4 L just before Christmas in a Sale on Amazon. While I used it a few times initially, I never got to do proper testing until recently. This was mainly because I was working super hard before Christmas, and then after Christmas, it pretty much rained here solid for two whole months. I’m not exaggerating, it really did rain almost non-stop for that long. When I did do some proper tests, I was a little frustrated at first, but figured I was doing something wrong. While there was really nice bokeh at the telephoto end, with the f/4 aperture delivering the goods, on some scenes I struggled to nail focus. This was on subjects that I would have no issues with on my STM version of the lens.

Then I noticed that while some images were nice and sharp, others were quite soft. Again, I thought I was doing something wrong, or that I was going mad, one or the other. I even did some comparisons with my F/4-F/7.1 version of the 24-105 just to see if I was imagining things. That's when it started to get a bit weird.

At 24 mm, if you shoot wide open at F/4 the lens is pretty sharp. It looks like what you would expect from a relatively expensive L series lens, and matches or exceeds the STM lens. Nothing to fault it at f/4. However, as soon as you start to stop down, it gets soft at the edges of the frame. I and not just the extreme corners, but about 10% all around. By f/8 this is quite noticeable. This is such an odd issue, as lenses normally do the opposite. They normally improve at the edges when you stop down. I’ve actually never heard of this before. I’ve never seen a lens get softer as you stop down.

Here you can see F/4 on the right, and F/7.1 on the left. You should be able to see how the f/7.1 version is much softer.

Here’s another example. Again, f/4 on the right.

Another issue, that I’m less convinced isn’t something I’m doing, is that it’s difficult to focus on certain subjects, at certain distances. For example, small flowers. The camera will tell you it’s in focus, but it will be slightly off. On a DSLR, you would say that this could be a calibration issue, but that shouldn’t really affect a mirrorless camera. Yet, the exact same subjects in the exact same lighting conditions, with the 34-105 F4-7.1 STM lens will have no trouble with these. Well, a little trouble, but that's normal. Now, this could just be user error, as there are a bajillion settings on the R6II. But it only really happens at 105 mm, and only at certain focus distances, which again makes me think it might be an issue with the lens. But it could be me. (Cue angry commenters telling me it is, in fact, me)

So I went and searched reviews of this lens and no one reported a similar finding. The 24 mm thing is so stark, I can’t believe that someone would have missed it in a normal review, so I guess it’s just my copy. After doing some more research, and downloading some online sample files, it really does seem like I have a bad copy. I always thought that the whole sample variation thing was just an internet myth. I can’t really understand how, with such expensive gear, you pretty much roll the dice whether or not you get a good one. This just doesn’t seem like a sustainable business model for companies. To be fair, this is the first time I’ve ever gotten a “bad” lens and of all the lenses I've had over the years, most have performed as expected. I also don’t think this is a “bad sample” either, I think it’s actually defective. It’s annoying because apart from this, it’s a pretty great lens. But it’s clearly not right.

I contacted Canon customer support about it, and they told me that it doesn’t sound right, and I need to send it in for service. So I will be doing that shortly, and I will report back with their findings once that happens.

If it wasn’t for the issues listed above it’’s a cracking lens (as you can see from this shot)

The thing is, I’d be really happy if this is something stupid I was doing, because I really don’t want to have to send this lens off. There’s a whole rigmarole trying to find the right box and what not. If anyone can think of anything at all that I might be doing wrong, please let me know. The only thing that I can think of is that it could be the stabiliser. I’m going to do some more tests soon before I send it off, with some more controlled experiments, to rule out a few more things.

If you’re wondering why I’m writing this at all, it’s because it’s such a specific problem that I wanted to share it in case anyone else out there had the same issue. So I guess for now it’s back to the STM version.

To be fair, the kit lens, while slower at the telephoto end, is actually a pretty good lens. For the most part, it’s razor sharp and produces wonderfully crisp images. The only two issues with it are that it’s quite slow on the telephoto end, at 7.1, and it’s not weather sealed. The bokeh isn’t quite as nice as the F/4L version, either. Anyway, if you’ve come across this issue before, or have had similar problems, please leave a comment below, not only to help me, but for any other readers which may have similar issues and have come across this page.

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