Have you ever wondered how the EF 24-70mm f/2.8L and EF 24-105mm f/4L zoom lenses would do if compared side by side? Which one would come out as the winner in real-world use? Here’s my answer to that question.

First, some recommended reading:

• Lens review: Canon EF 24-70mm f/2.8L USM
• Lens review: Canon EF 24-105mm f/4L IS USM

Those two reviews of mine should give you a good idea of what each lens can do. Now let’s talk about how they do when they’re together. 🙂 Here’s a photo of the two lenses. As you can see right away, the 24-105mm is smaller in both height and girth — it’s shorter and a little narrower than the 24-70mm.

When we look at the rear lens elements, we can see some differences there as well. The 24-105mm lens is on the left. If you look carefully, you can see a baffle in place. The 24-70mm lens has no baffle.

It’s possible that the baffle is there in order to reduce possible flare effects, since the focal range is longer. It could also be there to baffle us — after all, it is a baffle. 🙂 It’s also possible that the optics aren’t as high quality as those in the 24-70mm lens — they’re both priced the same, but the 24-105mm has image stabilization and an extra 35mm of range. On the other hand, I’ve seen a very similar baffle on the EF 14mm f/2.8L prime lens, and no one can say that the 14mm lens is made with cheap glass. So the more likely explanation is that it’s there to reduce lens flare due to the increased focal range.

(By the way, the baffle can be seen even more clearly in this product advisory from Canon warning about unacceptable levels of lens flare in early builds (2005) of the 24-105mm lens.)

Here’s another look at the lenses side by side, this time with the lens controls visible. As you can see, the only thing that’s different on the 24-105mm lens is that it’s got the IS switch. The controls seemed a little thicker on the 24-70mm lens. As for their durability, I assume they’re both long-lasting since these are L series lenses.

Chances are you can already know that the 24-105mm lens is lighter than the 24-70mm lens. It’s no small difference, by the way. The 24-105mm lens is 670g, while the 24-70mm lens is 950g — that’s 280g of difference! While both lenses extend outward as you zoom, the 24-70mm lens is more top-heavy than the 24-105mm lens, and that makes a big difference in wrist fatigue — the 24-105mm lens is less punishing and can be held comfortably for longer periods of time.

The weight difference is remarkable to me because the 24-105mm lens has 18 elements, while the 24-70mm lens has 16 elements. Canon managed to keep the weight down even though they placed extra glass in there and added image stabilization.

There are some limitations to being lighter and smaller though. The 24-105mm lens’ closest focusing distance is 1.48ft or 0.45m, while the 24-70mm lens’ closest focusing distance is 1.25ft or 0.38m. It also looks like the general consensus is that images obtained with the 24-105mm lens are somewhat softer than those obtained with the 24-70mm lens.

Other than the difference in focal lengths, another obvious difference between them is the maximum aperture. The 24-70mm lens opens up to f/2.8, while the 24-105mm lens only opens up to f/4. That’s a full f-stop difference, or a 2x reduction in the amount of light that can enter the lens. This is where the baffle comes in again. Since the baffle itself limits the amount of light that can hit the sensor in order to reduce glare, it stands to reason that the aperture can’t open up any wider. Even if it did, we’d end up seeing the baffle contours in our photos.

What the 24-105mm lens has going for it is the built-in image stabilization, which, in my experience, more than compensates for the reduced maximum aperture. See the photo below. I took it completely handheld (I didn’t prop myself up against anything) at a shutter speed of 1/15th seconds.

I tried to get similar photos with the 24-70mm lens, and I couldn’t, not without leaning against something to stabilize the lens. The slowest shutter speed I could use was 1/30th seconds with that lens. As I concluded in my previous review of the 24-105mm lens, the image stabilization counts for a lot and makes the lens truly versatile and useful.

While I’m talking about versatility, let’s not forget that extra 35mm of focal range. At close distances (6-15 feet), you don’t notice how much it matters, but when you start focusing on things farther away (30-100 feet or more), you realize how valuable those extra millimeters really are!

Let’s not forget bokeh. Both lenses have gorgeous bokeh, but the 24-70mm produces a creamier bokeh. That’s because it opens up all the way to f/2.8, while the other only opens up to f/4. If you do a lot of close-range photography, in tighter spaces, and you really need that bokeh (portraits, etc.), the 24-70mm would probably be a better candidate. This next photo was taken with the 24-70mm lens.

If you’ve got a little wiggle room and can position your subjects further away from things (walls, trees, background), don’t discount the 24-105mm lens. Its bokeh is right up there with the best of them. Have a look below.

In the end, it really comes down to your own, precise needs. I’ve heard of some people who only carry two lenses in their bag: the 24-70mm and the 70-200mm (both of which I reviewed here). They’re both professional-grade, L series lenses. They’re heavy, but they deliver the goods, and they’re versatile.

For my needs, I’d go with the 24-105mm lens. It’s lighter, has extra range, and has built-in image stabilization. I really enjoyed using it, and I seemed to get better photos with it than with the 24-70mm zoom. While it may not be as sharp, I didn’t notice anything that would turn me away from using it. I thought it was a superb lens and couldn’t believe the quality of the optics when I looked at the photos I got with it.

At least one commenter here asked how these two lenses compare, and I hope that I’ve answered that question in as much detail as I could give. If you have any other questions, pose them in the comments on this post, and I’ll try to answer them.

More information:

• EF 24-105mm f/4L IS USM Zoom specs on Canon website
• EF 24-70mm f/2.8L USM Zoom specs on Canon website
• EF 24-105mm f/4L IS USM listing at Amazon and B&H Photo
• EF 24-70mm f/2.8L USM listing at Amazon and B&H Photo