Canon RF 24-240mm f/4-6.3 IS USM – Review 2020

The Canon RF 24-240mm F4-6.3 IS USM ($899) offers as much zoom power as you’ll find in a full-frame lens, and manages to squeeze it into a zoom that’s relatively light and compact. It also makes the expected compromises—it doesn’t gather as much light as shorter zooms, and doesn’t offer quite the same level of image quality. But if you’re looking for a lens to capture wide views and distant subjects, the RF 24-240mm is a good choice to pair with Canon’s low-cost EOS RP.

Big Zoom Power

The 24-240mm isn’t as small as a prime, or similar ultra-zooms for APS-C systems, but when you consider that it works with bigger full-frame sensors, it’s surprisingly portable. The lens measures 4.8 by 3.2 inches (HD) at the 24mm position, but does telescope and extend when zoomed in.

Canon EOS R, 24mm, f/4.5, 1/1,250-sec, ISO 125

It’s also not that heavy, about 1.7 pounds, just a little more than the RF 24-105mm F4. There’s a thread for 72mm filters around the front glass, and the standard front and rear lens caps are included.

Aesthetics are basic. The lens is finished in black. Materials are sturdy—a composite-style plastic—but omit the weather protection you get with Canon’s upper echelon L series glass.

Canon EOS R, 240mm, f/7.1, 1/1,250-sec, ISO 250

There’s a lock switch to keep the lens set at 24mm, useful to have at its shortest position when it’s hanging at your side. The zoom ring is positioned toward the front. It’s rubberized, with the standard raised-ridge texture you find on most zoom lenses.

A second control ring is positioned behind it. It’s the same composite material as the rest of the barrel, but does have some texture, a diamond pattern, for a ready grip. It can control manual focus, or serve as a customizable control ring—a toggle switch swaps between the two settings.

Canon EOS R, 240mm, f/7.1, 1/1,600-sec, ISO 160

Focus is speedy, quick, and virtually silent. Breathing is minimal and the lens is stabilized, so it’s a good choice for handheld video. It doesn’t focus that close, though. At its best it locks onto subjects 1.6 feet (50cm) from the camera, so you can’t get up close and personal with subjects at wide angles. Still, because of the zoom power, the macro magnification is a decent 1:3.8 at 240mm; it’s more of a drawback when zoomed out.

Optical Performance

I paired the RF 24-240mm with the 30MP EOS R and Imatest software for testing in the lab. As you’d expect from a 10x zoom design, resolution isn’t on the same level as a prime lens or a pro-grade f/2.8 telezoom.

Canon EOS R, 24mm, f/4, 1/400-sec, ISO 100

At 24mm the aperture opens as wide as f/4. Imatest shows about 2,540 lines on a center-weighted sharpness evaluation, a result at the bottom end of the very good range for the EOS R’s 30MP sensor. Central resolution is stronger, in our excellent range (3,250 lines), but details soften as you look toward the periphery.

You’ll see a little more detail at f/5.6, and at f/8 you get the best performance from the lens. It hits 2,825 lines on average, very good, and shows about 3,500 at the center, on the border that separates excellent from outstanding. You’ll still see a loss of quality at the periphery—detail is just barely acceptable (2,075 lines) at the edges of the frame.

At narrower apertures—the lens can go down to f/22 at 24mm—resolution starts to drop off. You can still net good results at f/11 and f/16, but the loss of detail at f/22 is palpable. You should avoid using the lens beyond f/16 when possible.

Canon EOS R, 24mm, f/20, 1/320-sec, ISO 100

Photographers will sometimes go all the way to f/22 to net better-looking sunstars, but even at f/20, the ones this lens captures are a bit mushy, without clearly defined points.

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The f-stop narrows when the lens zooms in tighter. At 50mm it drops nearly a full stop to f/5. Resolution ticks up versus 24mm, though (2,650 lines, a very good result), but we see less of a drop in quality as you move away from center. It gets better at f/5.6 (2,851 lines) and delivers excellent results (3,024 lines) at f/8.

We next tested at 120mm, where the maximum aperture is just f/6.3. It’s here we see a noticeable drop in resolution. Wide open the performance isn’t that far off of what you get at 50mm, about 2,300 lines. But it never improves significantly, netting 2,400 lines at best. Results are about the same at 240mm.

Canon EOS R, 24mm, f/4, 1/800-sec, ISO 100

The lens relies on in-camera corrections to remove noticeable distortion and add some illumination to the corners of the image. If you use JPG mode on your camera, you’ll never have to worry about them. But photographers who use Raw format should take care to apply a correction profile. Without it, you’ll see darkened corners and visible barrel distortion. Adobe Lightroom includes a profile for the lens.

Vignette and Distortion Compensation Disabled

There is some chromatic aberration as well, visible as false purple and green color surrounding areas of high contrast. In-camera corrections will clear it away for most shots, but if you do prefer to work in Raw format you’ll need to take some care to remove it. Lightroom’s one-click tool gets rid of it in most instances, but you may have to add on slider adjustments 

The Single-Lens Solution

The RF 24-240mm covers a big zoom range, so your need to swap lenses when out for a photowalk or enjoying a vacation are greatly lessened. At its widest setting it covers the same angle as a pro 24-70mm lens, but zooms in much further. 

Canon EOS R, 24mm, f/4, 1/160-sec, ISO 100

The zoom power is enough for you to snap shots of your kid playing in a soccer league from the sidelines, something a standard zoom can’t quite manage. It’s a little short for photogs who are more serious about wildlife, and while it does net a telephoto advantage, it still skips covering ultra-wide views.

It doesn’t gather as much light as its professionally geared cousins, but it costs a fraction of what you’d spend to get the RF 24-70mm F2.8 and RF 70-200mm F2.8 together. Many hobbyists aren’t able to budget thousands for photo gear.

If you find appeal in the all-in-one design, the RF 24-240mm may tickle your fancy. You do have some other choices, though. The RF 24-105mm F4-7.1 is a recent announcement, not yet shipping, for $400, and is going to be a kit option for entry-level EOS RP.

Canon EOS R, 24mm, f/11, 1/320-sec, ISO 100

For a bit more than the 24-240mm, the $1,100 RF 24-105mm F4 offers better optics, dust and splash protection, and a dedicated control ring. If you value image quality over convenience, it’s a better way to spend your money.

But if you prefer a single lens, the RF 24-240mm does a good job balancing price, performance, and size, and smartly leverages the processing power of your digital camera to net images better than its optics could manage on their own.

Canon RF 24-240mm F4-6.3 IS USM Specs

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