Canon RF 14-35mm F4 L IS USM Lens Review

Canon RF 14-35mm F4 L IS USM Lens

The Canon RF 14-35mm F4 L IS USM Lens is the ultra-wide to wide member of what could be considered the trinity of essential RF f/4 zoom lenses, a set of high-performing, lightweight, compact, moderately priced, professional-grade lenses that cover a vast majority of the commonly used focal lengths.

  • 14mm is extremely wide, and the entire range is useful
  • Outstanding landscape and architecture lens
  • Sharp image quality
  • Professional grade
  • Fast, silent, and smooth Nano USM AF
  • Quiet optical image stabilization
  • Moderately priced
  • Compact
  • Lightweight
  • Strong wide end barrel distortion requires correction
  • Slightly soft at 35mm f/4
  • Strong lateral CA at wide end
In-Depth Review

I consider an ultra-wide-angle zoom lens an essential part of my kit and rarely go anywhere without such a lens in the bag. When light weight, compact size, and moderate price are important, and those attributes frequently are for a lens in this class, the Canon RF 14-35mm F4 L IS USM Lens rises to the top of the ultra-wide-angle zoom lens shortlist. The remarkable focal length range, reaching from 14mm all the way to 35mm, increases the versatility of this lens. Add excellent performing Nano USM AF and image stabilization along with this lens's impressive optical quality, and the other candidates on the list fall away.

During a conversation with Canon's engineers at the launch of the RF mount, it was promised that all RF lenses would have advantages over their EF counterparts. The RF 14-35mm F4 L IS USM Lens's EF counterpart is the Canon EF 16-35mm f/4L IS USM Lens, and the RF's two extra mms of focal length on the wide end are a huge and obvious advantage. In addition, even without a mount adapter factored in, the RF lens has a smaller size and a modestly lighter weight. The RF 14-35 also has a 1.5-stop higher-rated image stabilization system to its advantage.

Canon's engineers indicated that image quality, advantaged by new lens design opportunities made available by the optimized RF mount, would be minimally equivalent and often better. Canon's earliest RF mount lenses set the image quality bar high, and the RF 14-35 does not disappoint in that regard. The EF 16-35mm f/4L IS lens is optically stellar, but, remarkably, the RF 14-35mm F4 L modestly outperforms it in most comparisons.

The RF 14-35's image quality is excellent, the Nano USM AF system is silent, fast, and accurate, and the L-series build quality promises to hold up to the rigors of constant use. Those features, along with the versatility that this lens provides, make the Canon RF 14-35mm F4 L IS USM Lens a great ultra-wide-angle zoom lens choice.

Canon RF 14-35mm F4 L IS USM Lens Top View

Focal Length Range

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The focal length range availed is the first aspect to consider for zoom lens selection. Focal length drives subject distance choices which determine perspective.

Often, one cannot back up far enough to get a large subject or vast scene in the frame, and in that case, an ultra-wide-angle zoom lens is the right choice. When a foreground subject is to be emphasized, rendered large in relation to a vast background (potentially in sharp focus), moving in close with an ultra-wide-angle zoom lens is the right choice.

Note that covering the 14-35mm focal length range in a single full-frame lens is remarkable. While other full-frame zoom lenses cover 14mm or even wider, none of them reach the ultra-popular 35mm focal length on the long end. Other full-frame zoom lenses reach 35mm on the long end, but even the sibling Canon RF 15-35mm F2.8 L IS USM Lens does not reach 14mm. At small number focal lengths, even one mm is a significant percentage change, making a substantial difference in the realized angle of view.

What subjects are this versatile ultra-wide-angle zoom lens ideal for? That list is huge, but let's discuss a few of the genres most-photographed by this lens class.

Which photography genre has the hugest subjects? While astrophotographers arguably have the largest subjects (this lens lacks the ultra-wide aperture ideal for that use), landscape photography is also a great answer to that question. It's a big world, and the 14-35mm focal length range is a perfect choice for capturing the beauty of our planet.

Canon RF 14-35mm F4 L IS USM Lens Top View

This lens gives us reason to go out and enjoy the great outdoors.

Another genre of photography with huge subjects, often including some landscape, is real estate photography, and this lens is a solid interior and exterior choice for this use. Directly related to real estate photography is architecture photography. This lens will take in massive structures even when a short working distance is available.

When photographing real estate and architecture, a level camera is often desired to keep walls and the sides of buildings straight/vertical in the frame, avoiding converging lines. However, it is not always possible, affordable, or convenient to get the camera to a height that permits the optimal framing with a level camera. This need is especially common when photographing the exterior of buildings from ground level.

A tilt-shift lens is the ideal answer to that problem, but an ultra-wide-angle lens can also get the job done. Simply set up the camera in a level position, zoom out until the building (or other subject) is contained in the frame, capture the image, and then crop whatever is not desired in the frame, typically at the bottom, during post-processing. Basically, having a lens that takes in wide angles of view can circumvent the need for a tilt-shift lens (with resolution loss from the cropping being a downside) or pixel-level-destructive perspective correction.

Usually, the structures we photograph are built for people, and people are a good subject for this focal length range.

While a close-up wide-angle perspective can look amazing in a landscape scene, it is generally to be avoided when a person is the primary subject. We do not typically look at a person from really close distances, and if we do, that person becomes uncomfortable with us being in their personal space (and even more so when a camera is in hand). When we look at photos of people captured from close distances, certain body parts (usually the nose) start to look humorously (to some) large. Unique portrait perspectives can be fun, but this technique should not be overused as it quickly gets old. Get the telephoto lens out for your tightly framed portraits.

However, wide-angle focal lengths can be a great choice for photographing people. Simply move back and include people in a larger scene, creating environmental portraits.

The 35mm focal length provides a natural perspective and is a great choice for full-body portraits. This focal length range also nicely handles small up to large groups. Note that group photography requiring an ultra-wide-angle focal length to fit everyone in the frame often leaves those in the front row appearing considerably larger than those in the back row (the subject distance varies by a significant percentage). Back up or move the subjects closer together (front to back) to reduce the multi-row perspective issue.

The 14-35mm focal length range is the perfect option for the wide work at weddings, family gatherings, and other events, and for photojournalism and sports photography needs when the f/4 aperture is sufficient.

The following images illustrate the 14-35mm focal length range:

Canon RF 14-35mm F4 L IS USM Lens Focal Length Range Example

14mm | 15mm | 16mm | 17mm | 18mm | 20mm | 24mm | 28mm | 35mm

The 15, 16, 17, and 18mm focal lengths are not marked on this lens, but the EXIF reported the focal lengths matching the labels. At ultra-wide angles, a small change in the focal length imparts a big angle of view change. While the estimated lengths above could be slightly off, 14mm is much wider than 16mm.

Utilizing a smaller portion of the image circle means that APS-C sensor format cameras see a narrower angle of view, with 1.6x being the multiplier (FOVCF) for Canon's lineup. There are currently no RF-mount APS-C format cameras in production, but this lens will show a full-frame angle of view equivalent of 22.4-56mm should such a camera become available. While not as ultra-wide angle on the small format imaging sensor, this range works great for landscape use and even greater for portrait photography.

Videographers will find the 14-35mm focal length range equally useful as still photographers, and this lens is, in many ways, optimized for video recording.

Canon RF 14-35mm F4 L IS USM Lens Front View

Max Aperture

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The lower the aperture number, the wider the opening, and the more light the lens can allow to reach the imaging sensor. Each "stop" in aperture change (full stop examples: f/1.4, f/2.0, f/2.8, f/4.0) increases or decreases the amount of light reaching the sensor by a factor of 2x (a substantial factor).

Wide aperture lenses, allowing more light to reach the sensor, permit freezing action and handholding the camera in lower light levels and can also enable the use of lower (less noisy) ISO settings. In addition to allowing more light to reach the sensor, increasing the aperture opening provides a shallower DOF (Depth of Field) that creates a stronger, better subject-isolating background blur (at equivalent focal lengths). Often important is that low light AF performance is improved by an increased amount of light reaching the imaging sensor.

A narrow aperture's advantages are related to (often significantly) reduced lens element size and include smaller overall size, lighter weight, and lower cost. Right, everyone loves those factors.

Because the aperture is measured as a ratio of lens opening to focal length, the focal length must be taken into consideration when assessing how wide a lens's aperture can open. At 600mm, f/4 is a massive opening. In a 14-35mm lens, f/4 is relatively narrow, and this lens was designed to take advantage of the small size, light weight, and lower cost advantages.

Especially in the ultra-wide-angle zoom focal length range, wide apertures are not always needed.

Motion blur is caused when subject details cross over imaging sensor pixels during the exposure. Although this lens can be used with a close subject rendered large in the frame, lenses such as this one are often used at normal (or even long) subject distances. The low magnification means those subjects' details more readily stay in their pixels, permitting the longer exposures required to compensate for the narrower aperture to still deliver sharp results, free of subject or camera motion blur.

Many of the uses for this lens mandate a narrower aperture, such as f/8 or f/11, to keep everything in the frame sharp, and photographers concentrating on landscape, architecture, real estate, etc. may seldom use the f/4 option.

Still, f/4 reduces this lens's capabilities modestly relative to the f/2.8 zoom lens options available in this class. Those photographing moving subjects, such as at sports events or under the night sky where light levels are so low that the earth's rotation becomes a source of camera motion, may prefer a wider aperture lens to the increased ISO setting alternatively required.

It is hard to diffusely blur the background with the low magnification provided by an ultra-wide-angle lens. Such lenses render the background details small in size, keeping the background subjects more recognizable (and potentially distracting). Still, this lens's short minimum focus distance can make that happen, adding artistic advantages to this lens's list of highly-desired features.

These examples illustrate the maximum blur this lens can create:

Canon RF 14-35mm F4 L IS USM Lens Maximum Blur Example

14mm | 24mm | 35mm

When recording video, only 1/60 second shutter speeds (twice the framerate) are typically needed (assuming you're not capturing high framerate slow-motion video), and wide apertures are not often required for 1/60 second rates in normally encountered ambient lighting.

Most will appreciate this lens's constant max aperture, enabling f/4 throughout the focal length range.

Canon RF 14-35mm F4 L IS USM Lens on Tripod

Image Stabilization

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When the subject is not moving or not moving much, this lens's image stabilization system, rated for 5.5 stops of assistance, can make a huge difference in handheld image quality. Use this lens on an EOS R-series camera featuring In-Body Image Stabilization (IBIS), and that rating jumps to a crazy 7 stops. The 7 stop ISO noise difference referenced by this rating is dramatic.

IS is useful for stabilizing the viewfinder, aiding in optimal composition (though this is not as big of an issue with wide-angle focal lengths). IS is also useful for video recording, helping viewers to avoid that motion sickness feeling.

The image stabilization system in the RF 14-35 performs superbly. IS makes a faint "hmmm" (even when switched off), though it is audible only from about an inch or two from the lens. Canon's IS systems have long been well behaved, meaning that the viewfinder image does not jump and I do not find myself fighting against IS while recomposing or recording video. I see the image framing drifting only slightly while IS is active.

Canon RF 14-35mm F4 L IS USM Lens Side View

This highly refined image stabilization system, as mentioned, gets a very-high 5.5-stops of assistance rating and 7 stops with IBIS. Improved communications between the lens and the camera via the new RF mount makes these impressive ratings possible.

The testing needed to be done, but thanks to various stressors occuring in the day, it was one of my shakier image stabilization tests. Despite the camera visibly shaking during the exposures (including heartbeats at the shutter durations being tested), the R5 and RF 14-35 combination turned in mostly sharp 14mm images at incredibly long 1.6-second exposures. Even some of the 2-second exposures were sharp. With elbows rested, most 5-second exposures were sharp at 14mm. A solid percent of the 35mm results were sharp at 0.5-seconds, and sharp images were still being made at 1-second exposures.

This is a impressive high-performing IS system.

Canon RF 14-35mm F4 L IS USM Lens on Tripod

Image Quality

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The photographers using ultra-wide-angle lenses tend to be among the most fastidious. Paramount is that our lenses to produce sharp results from the center into the extreme corners.

I have good news — this one meets that requirement. Especially nice is that the performance of optically great lenses is easy to describe.

Overall, this lens is extremely sharp in the center of the frame, including at f/4. The 35mm f/4 results are slightly hazy, slightly softer than the balance of the range, but these sharpen up nicely by f/4.5 and f/5.6. Otherwise, stopping down yields little improvement, and no improvement is needed.

In general, lenses are not as sharp in the periphery, where light rays are refracted to a stronger angle than in the center. Again, aside from the 35mm result, this lens produces excellent peripheral sharpness wide open, with little improvement realized or needed at narrower apertures. At 35mm, the peripheral results are slightly soft at f/4 but sharpen nicely by f/5.6

Taking the testing outdoors, we next look at a series of center-of-the-frame 100% resolution crop examples. These images were captured using an ultra-high resolution Canon EOS R5 with RAW files processed in Canon's Digital Photo Professional (DPP) using the Standard Picture Style with sharpness set to 1 on a 0-10 scale. Note that images from most cameras require some level of sharpening, but too-high sharpness settings (often including the default settings) are destructive to image details and hide the deficiencies of a lens.

Usually, I share sets of images that show the improvement realized at narrower apertures. Aside from the 35mm results, this lens produces wide open sharpness so good that the extra aperture examples were superfluous and, therefore, omitted. Instead, more subject samples than usual are included.

Canon RF 14-35mm F4 L IS USM Lens Sharpness Comparison Example

14mm: f/4.0 | f/4.0 | f/4.0 | f/4.0 | f/4.0 | f/4.0
24mm: f/4.0 | f/4.0 | f/4.0 | f/4.0 | f/4.0 | f/4.0
35mm: f/4.0 | f/5.6  f/4.0 | f/5.6  f/4.0 | f/5.6
35mm: f/4.0 | f/5.6  f/4.0 | f/5.6  f/4.0 | f/5.6

The contrast and resolution difference between 35mm f/4 and f/5.6 is noticeable, warranting sharing of the additional samples.

Be sure to find details in the plane of sharp focus for your evaluations. As you can see above, this lens produces overall excellent contrast and resolution.

Next, we'll look at a comparison showing 100% extreme-top-left-corner crops captured and processed identically to the above center-of-the-frame images. The lens was manually focused in the corner of the frame to capture these images.

Canon RF 14-35mm F4 L IS USM Lens Corner Sharpness Comparison Example

24mm: f/4.0 | f/5.6  f/4.0 | f/5.6  f/4.0 | f/5.6  f/4.0 | f/5.6
35mm: f/4.0 | f/5.6  f/4.0 | f/5.6  f/4.0 | f/5.6

Samples taken from the outer extreme of the image circle, full-frame corners, can be counted on to show a lens's weakest performance, but again, these results look great, especially for the ultra-wide-angle focal lengths. The 35mm results remain a touch weaker than the wider angle samples.

Corner sharpness does not always matter, but it does matter for many disciplines this lens will be utilized for, including landscape photography. This lens delivers nicely in that regard.

Focus shift, the plane of sharp focus moving forward or backward as the aperture is narrowed (residual spherical aberration or RSA), is not an issue exhibited by this lens. At 35mm, increased depth of field at narrower apertures is noticeably greater behind the subject, but the subject remains in sharp focus.

When used on a camera that utilizes a lens's entire image circle, peripheral shading can be expected at the widest aperture settings. This lens's strongest shading, a moderate about-2.5 stops, is found at the wider end of the range. The f/4 shading decreases as the focal length increases, dropping to below 2 stops at 28mm and to about 1.5 stops at 35mm, both relatively low numbers for a wide-open aperture. A modest reduction in peripheral shading is seen at f/5.6 and again at f/8. Little or no further reduction is seen at f/11, with just over 1.5 stops of shading remains in the corners at the wider half of the range, just over 1 stop at 28mm, and just under 1 stop at 35mm.

If APS-C format cameras become compatible with RF lenses, the smaller imaging sensor using the centermost portion of the frame will, with under a stop of shading, avoid most vignetting problems.

One-stop of shading is often used as the visibility number, though subject details provide a widely varying amount of vignetting discernibility (blue skies readily show vignetting effects). While the full-frame f/11 shading at the wider focal lengths is above the visibility numbers, these results are not unusual for the lens class.

Vignetting is correctable during post-processing with increased noise in the brightened areas being the penalty, or it can be embraced, using the effect to draw the viewer's eye to the center of the frame. Study the pattern showing in our vignetting test tool to determine how your images will be affected.

Lateral (or transverse) Chromatic Aberration (CA) refers to the unequal magnification of all colors in the spectrum. Lateral CA shows as color fringing along lines of strong contrast running tangential (meridional, right angles to radii) with the mid and especially the periphery of the image circle showing the most significant amount as this is where the most significant difference in the magnification of wavelengths typically exists.

With the right lens profile and software, lateral CA is often easily correctable (often in the camera) by radially shifting the colors to coincide. However, it is always better to avoid this aberration in the first place.

Color misalignment can be seen in the site's image quality tool, but let's also look at a set of worst-case examples. The images below are 100% crops from the extreme top left corner of EOS R5 frames showing diagonal black and white lines.

Canon RF 14-35mm F4 L IS USM Lens Lateral Chromatic Aberration Example

14mm | 20mm | 24mm | 28mm | 35mm

Only black and white colors should appear in these images, with the additional colors indicating lateral CA. The amount of lateral CA showing here is relatively strong and unusually consistent over the range. Typically, zoom lenses show strong lateral CA at their shortest and longest focal lengths with decreasing and then increasing amounts in the middle.

A relatively common lens aberration is axial (longitudinal, bokeh) CA, which causes non-coinciding focal planes of the various wavelengths of light. More simply, different colors of light are focused to different depths. Spherical aberration along with spherochromatism, or a change in the amount of spherical aberration with respect to color (looks quite similar to axial chromatic aberration but is hazier) are other common lens aberrations to observe. Axial CA remains somewhat persistent when stopping down, with the color misalignment effect increasing with defocusing. The spherical aberration color halo shows little size change as the lens is defocused, and stopping down one to two stops generally removes this aberration.

In the real world, lens defects do not exist in isolation, with spherical aberration and spherochromatism generally found, at least to some degree, along with axial CA. These combine to create a less sharp, hazy-appearing image quality at the widest apertures.

The examples below look at the defocused specular highlights' fringing colors in the foreground vs. the background. The lens has introduced any fringing color differences from the neutrally-colored subjects.

Note that the first image in each focal length pair shared below was focused in front of the subject, and the second example was focused beyond. Compare the image pairs for color consistency.

Canon RF 14-35mm F4 L IS USM Lens Spherical and Axial Aberration Example

14mm | 14mm   24mm | 24mm   35mm | 35mm

Overall, the color separation shown here is modest.

Bright light reflecting off of lens elements' surfaces may cause flare and ghosting, resulting in reduced contrast and sometimes interesting, usually destructive visual artifacts. The shape, intensity, and position of the flare in an image are variable, dependant on the position and nature of the light source (or sources), selected aperture, shape of the aperture blades, and quantity and quality of the lens elements and their coatings. Canon combats flare and ghosting with Sub-wavelength Structure Coating (SWC) and Air Sphere Coating (ASC) — with success as our sun in the corner of the frame flare test produced few flare effects, even at f/16.

Flare effects can be embraced or avoided, or removal can be attempted. Removal is sometimes challenging. High flare resistance is an especially welcomed trait for an ultra-wide-angle lens, and especially for one used outdoors.

Two lens aberrations are particularly evident in images of stars, mainly because bright points of light against a dark background make them easier to see. Coma occurs when light rays from a point of light spread out from that point instead of being refocused as a point on the sensor. Coma is absent in the center of the frame, gets worse toward the edges/corners, and generally appears as a comet-like or triangular tail of light which can be oriented either away from the center of the frame (external coma) or toward the center of the frame (internal coma). Coma clears as the aperture is narrowed. Astigmatism is seen as points of light spreading into a line, either sagittal (radiating from the center of the image) or meridional (tangential, perpendicular to sagittal). This aberration can produce stars appearing to have wings. Remember that Lateral CA is another aberration apparent in the corners.

The images below are 100% crops taken from the top-right corner of EOS R5 frames.

Canon RF 14-35mm F4 L IS USM Lens Coma Example

14mm | 24mm | 35mm

The stretched stars indicate that coma is present. While the amount is noticeable, it is not unusually so.

As seen earlier in the review, it is easy to illustrate the amount of blur a lens can create, and wide-angle lenses are inherently disadvantaged in this regard. Due to the infinite number of variables present among all available scenes, assessing the bokeh quality is considerably more challenging. Below are some f/11 (for diaphragm blade interaction) examples.

Images in the first two sets are f/11 100% crops. The last set of images are full f/8 images reduced in size.

Canon RF 14-35mm F4 L IS USM Lens Bokeh Example

14 | 24 | 35   14 | 24 | 35   14 | 24 | 35

The defocused highlight shapes remain quite round at f/11, and especially the results from the longer focal lengths are smoothly filled.

Except for a small number of specialty lenses, the wide aperture bokeh in the frame's corner does not produce round defocused highlights, with these effects taking on a cat's eye shape due to a form of mechanical vignetting. If you look through a tube at an angle, similar to the light reaching the frame's corner, the shape is not round, and that is the shape seen here. The examples below are upper-left quadrant crops reduced in size.

Canon RF 14-35mm F4 L IS USM Lens Cat's Eye Bokeh Example

14mm | 20mm | 24mm | 28mm | 35mm

As the aperture narrows, the entrance pupil size is reduced, and the mechanical vignetting absolves with the shapes becoming rounder.

With a 9-blade count diaphragm, point light sources captured with a narrow aperture setting and showing a sunstar effect will have 18 points. In general, the more a lens diaphragm is stopped down, the larger and better-shaped the sunstars tend to be. While this lens's moderate f/4 max aperture opening is not optimal for this effect, it still manages to produce nicely shaped and reasonably-sized sunstars.

Canon RF 14-35mm F4 L IS USM Lens Sunstar Effect Example

The example above was captured at 24mm, f/16.

To keep your opinion unbiased, an important aspect of this lens was withheld until this point in the review. This lens has significant barrel distortion over the wider half of the focal length range. The geometric distortion is strong enough that Canon forces the correction in camera and in DPP, regardless of the lens corrections settings.

The RF 14-35 distortion test results shared in the site's distortion tool were processed to show the uncorrected distortion. Here is another look:

Canon RF 14-35mm F4 L IS USM Lens Distortion Example

14mm | 16mm | 20mm | 24mm | 28mm | 35mm

The resolution chart is framed at the edge of the 3:2 ratio arrows, and the additional area included in the frame represents the corrected away portion of the image.

At 14mm, there is a lot of extra subject in the frame, and the straight line at the top of the chart is rendered in a strong curve. Though still relatively strong, the 16mm distortion is looking considerably better. By 20mm, it appears that little correction would be necessary — less than the amount applied — and the 24mm through 35mm results look good without any correction applied.

Although today's image correction AI is good, AI does not really know what the subject details were in the stretched areas, and calling the result fake detail does not seem untrue.

Here are the results as processed in DPP:

Canon RF 14-35mm F4 L IS USM Lens Distortion Corrected Example

14mm | 20mm | 24mm | 28mm | 35mm

Does the strong distortion correction matter? Psychologically it does, and an image captured from a non-distorted lens can similarly be up-sized to even higher resolution using AI, potentially giving it an advantage. That said, did you notice any corner issues until this point in the review? Likely not substantial ones.

I need to get over the psychological issue of the geometric distortion correction, but otherwise, this lens is a stellar performer. The lateral CA is relatively high, though this issue is typically easily corrected. The center of the frame image quality at 35mm, f/4 lags slightly, but by only f/4.5 and f/5.6, this focal length falls in line with the other outstanding performers. This lens delivers excellent image quality.

Canon RF 14-35mm F4 L IS USM Lens Angle View


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The combined performance of a camera and lens's autofocus system is critical to realizing the potential image quality of the combination (unless manual focusing is in use). The Canon RF 14-35mm F4 L IS USM Lens receives a high-performing Nano USM (Ultrasonic Motor) driven AF system. This technology first arrived in the L-series with the Canon RF 24-105mm F4 L IS USM Lens and is now frequently featured in other designs, including the Canon RF 15-35mm F2.8 L IS USM Lens. The RF 14-35mm F4 lens's AF system repeats the performance of these others.

Nano USM acts like an ultra-fast version of STM AF, combining the benefits of a high-speed Ring USM actuator with an STM system stepping motor's quiet and smooth, direct, lead screw-type drive system. Like Ring USM driven AF systems, Nano USM focuses extremely fast – nearly instantly. Like STM AF systems, Nano USM focuses almost silently, with a faint clicking heard only when one's ear is next to the lens. And, Nano USM lenses focus smoothly, making video focus distance transitions easy on the viewer's eyes. Even the lens's aperture changes are quiet and smooth.

The Nano USM illustration below is borrowed from the RF 15-35 review.

Canon RF 15-35mm F2.8 L IS USM Lens Nano USM

Canon U.S.A.'s Rudy Winston states: "Canon’s new Nano USM technology uses a completely different form factor, but achieves focus results within the lens via the same principles of ultrasonic vibration energy, transmitted here into linear (rather than rotational) movement within the lens. This tiny new Ultrasonic motor achieves the combination of fast, near-instant response during still image shooting, with the smoothness required for good focus during video recording."

Ring USM was Canon's former preference for high-end lens AF systems. While most Ring USM lenses are great performers, they generally do not focus so smoothly in Movie Servo AF, and the Ring USM EF lenses produce considerably more focus chatter. Nano USM (and STM) lenses autofocus substantially smoother and quieter than Ring USM lenses.

Of utmost importance is AF accuracy, and from that perspective, the Canon RF 14-35mm F4 L IS USM Lens performance is excellent.

An f/4 lens is not usually the first choice for photographing in low light environments, but with an EOS R5 behind it, the Canon RF 14-35mm F4 L IS USM Lens can lock focus on contrasty subjects under quite dark conditions.

Canon RF 14-35mm F4 L IS USM Lens Side View with Hood

The rubber-ribbed focus ring is relatively small and positioned in front of the zoom ring (this is my strongly preferred position).

Like STM-driven AF, Nano USM utilizes a focus-by-wire or electrical manual focus design (vs. a direct gear-driven system). The manual focus ring electronically controls the focus of the lens.

FTM (Full Time Manual) focusing is supported in AF mode with the camera in One Shot Drive Mode, but the shutter release must be half-pressed for the focus ring to become active. Note that FTM does not work if electronic manual focusing after One Shot AF is disabled in the camera's menu. The lens's switch must be in the "MF" position and the camera meter must be on/awake for conventional manual focusing to be available.

With electronics driving AF, the rate of focus change caused by the focus ring is electronically controlled, and it can be variable, based on the ring's rotation speed. With the R-series cameras, a linear adjustment speed can be configured, disabling a variable rate if such is available. That option is usually my preference, and in this mode, the RF 14-35 F4 L focus is adjusted slowly, with approximately 195° of ring rotation from MFD to infinity, good for manual focusing precision. Switch to the variable adjustment mode and turn the ring fast to get the full range in 140°.

The manual focus ring has an ideal resistance, and focus adjustments are relatively smooth (a slight stepping adjustment is visible under full zoom) and solidly centered with no unusual framing shift happening.

Normal is for subjects to change size in the frame (sometimes significantly) as the focus is pulled from one extent to the other. This effect is referred to as focus breathing, a change in focal length resulting from a change in focus distance. Focus breathing has negatively implications for photographers intending to use focus stacking techniques, videographers pulling focus, and anyone critically framing while adjusting focus. Modest (normal) subject magnification changes are seen in full extent focus range changes.

Canon RF 14-35mm F4 L IS USM Lens Focus Magnification Example

14mm: Far | Close   35mm: Far | Close

The review lens does not exhibit parfocal-like behavior. Though subjects focused on at 35mm remain in sharp focus throughout most of the focal length range, they become noticeably blurred at the 14mm end due to the plane of sharp focus moving forward. The 100% crops below illustrate this behavior.

Canon RF 14-35mm F4 L IS USM Lens Parfocal Example

35mm | 28mm | 24mm | 20mm | 17mm | 14mm

If you adjust the focal length, re-establish focus. This rule usually applies.

This lens has an AF/MF switch, allowing that frequently used camera setting to be quickly changed without diving into the menu system.

With a minimum focus distance of 7.9" (200mm), the RF 14-35 has an impressively high 0.38x maximum magnification spec. There are few non-macro lenses of any focal length with max magnifications specs close to this one.

ModelMin Focus Distance "(mm)Max Magnification
Canon RF-S 10-18mm F4.5-6.3 IS STM Lens5.5(140)0.23x
Canon RF 10-20mm F4 L IS STM Lens9.8(250)0.12x
Canon RF 14-35mm F4 L IS USM Lens7.9(200)0.38x
Canon RF 15-30mm F4.5-6.3 IS STM Lens5.1(130)0.52x
Canon RF 15-35mm F2.8 L IS USM Lens11.0(280)0.21x
Canon RF 24-70mm F2.8 L IS USM Lens8.3(210)0.30x
Canon RF 24-105mm F4 L IS USM Lens17.7(450)0.24x
Sony FE 12-24mm f/2.8 GM Lens11.0(280)0.14x
Sony FE 12-24mm f/4 G Lens11.0(280)0.14x
Sony FE 16-35mm F2.8 GM II Lens8.7"(221)0.32x
Sony FE PZ 16-35mm F4 G Lens11.0"(280)0.23x
Tamron 17-28mm f/2.8 Di III RXD Lens7.5(190)0.19x

At 14mm, a subject measuring approximately 7.8 x 5.2" (198 x 132mm) fills a full-frame imaging sensor at this lens's minimum focus distance. At 35mm, a 3.8 x 2.5" (97 x 65mm) subject does the same.

The example below shows the 35mm magnification capability.

Canon RF 14-35mm F4 L IS USM Lens 35mm Maximum Magnification Example

This image shows a similar perspective from the 14mm end.

Canon RF 14-35mm F4 L IS USM Lens 14mm Maximum Magnification Example

While the butterfly in the image below was a bit beyond the minimum focus distance, it helps to illustrate the close-focusing concept.

Canon RF 14-35mm F4 L IS USM Lens Maximum Magnification Example

Often when lenses have high maximum magnification capabilities, the image quality suffers significantly at the closest focus distances. Fortunately, this lens continues to deliver excellent image quality at close focus distances.

Remember that minimum focus distance is measured from the imaging sensor plane, with the balance of the camera, lens, and lens hood length taking their space out of the number to create the working distance. Without the hood in place, this lens's minimum focus distance provides about 2.2" (56mm) of working distance. Lighting subjects at this distance can be challenging, and adding the lens hood further complicates that challenge.

Need a shorter minimum focus distance and higher magnification? Mount an extension tube behind this lens for a significant decrease and increase those respective numbers. The change is likely dramatic enough that focus will not be obtainable at the wide end of the focal length range even with the thinnest extension tube in use. Extension tubes are hollow lens barrels that shift a lens farther from the camera, allowing shorter focusing distances at the expense of long-distance focusing. Electronic connections in extension tubes permit the lens and camera to communicate and otherwise function as normal. Canon does not offer RF mount-compatible extension tubes as of review time, but third-party options are available.

This lens is not compatible with Canon extenders.

Build Quality & Features

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It's a member of the L lens series, and that means this lens is designed for the high reliability and durability required by professional use. While these attributes are crucially important to professionals, a huge number of serious amateurs also recognize the importance of high quality.

Canon's RF L lenses have taken on a slightly updated look over the EF L models, but those familiar with EF L lenses will immediately recognize this lens's L-Series heritage, highlighted by the red ring. The RF L-series lens look and feel has now become firmly established, and this lens fits that mold.

Canon RF 14-35mm F4 L IS USM Lens Product Images

MFD |    MFD |    w/ Hood:  MFD |    MFD |    Rotated   Compare »

With smooth external dimensions and tight tolerance between parts, the Canon RF 14-35mm F4 L IS USM Lens is comfortable to hold, and it is a pleasure to use.

The rear-positioned, smooth-functioning zoom ring is ideally located behind the focus ring. A slight diameter increase on the zoom ring, a design feature becoming common throughout the RF lens lineup, makes it easy to find. With the RF lenses gaining an additional ring and the rings consuming a significant percentage of the barrel, finding the right ring becomes modestly more complicated, and tactile cues such as this one, are helpful. With the zoom and focus rings located immediately adjacent to each other, finding this lens's manual focus ring without looking is not so easy. Note that the review lens's image center moves slightly during a full extent focal length change.

The additional ring is the knurled "Control Ring", able to be configured for fast access to settings including aperture, ISO, and exposure compensation. A small amount of space is provided between the focus and control rings, aiding slightly in selecting between the two. Note that the control ring is clicked by default, and this ring's clicks are going to be audible in camera-based audio recordings. Canon offers a click stop removal service for this ring (at a cost).

This lens features a quality plastic external construction. As illustrated in some of the product images in this review, this lens extends slightly (0.37", 9.3mm) when zoomed from about 21mm to 14mm or 35mm. The extended inner lens barrel has essentially no play. An extension lock switch is not provided and was not needed.

The AF/MF and IS switches are flush-mounted and low-profile, with just enough raised surface area available for easy use, even with gloves. These switches snap crisply into place. Interesting is that changing the AF/MF switch position opens the lens aperture momentarily when the camera is powered off.

Canon RF 14-35mm F4 L IS USM Lens Mount

While not waterproof, this lens's weather sealing can save the day.

Canon RF 14-35mm F4 L IS USM Lens Weather Sealing

Like most other recent L lenses, the RF 14-35mm f/4 features fluorine coatings on the front and rear lens elements to avoid adhesion of dust and liquids and to make cleaning easier. This is one of those features that goes unnoticed ... until something happens in the field.

This lens's small size and light weight are huge advantages it holds. Those spending long amounts of time with this lens in hand or in a carried case will love these features.

ModelWeight oz(g)Dimensions w/o Hood "(mm)FilterYear 
Canon RF-S 10-18mm F4.5-6.3 IS STM Lens5.3(150)2.7 x 1.8(69.0 x 44.9)492023
Canon RF 10-20mm F4 L IS STM Lens20.1(570)3.3 x 4.4(83.7 x 112.0)n/a2023
Canon RF 15-30mm F4.5-6.3 IS STM Lens13.8(390)3 x 3.5(76.6 x 88.4)672022
Canon RF 14-35mm F4 L IS USM Lens19.1(540)3.3 x 3.9(84.1 x 99.8)772021
Canon RF 15-35mm F2.8 L IS USM Lens29.7(840)3.5 x 5.0(88.5 x 126.8)822019
Canon RF 24-70mm F2.8 L IS USM Lens31.8(900)3.5 x 4.9(88.5 x 125.7)822019
Canon RF 24-105mm F4 L IS USM Lens24.7(700)3.3 x 4.2(83.5 x 107.3)772018
Sony FE 12-24mm f/2.8 GM Lens29.9(847)3.8 x 5.4(97.6 x 137.0)n/a2020
Sony FE 12-24mm f/4 G Lens19.9(565)3.4 x 4.6(87.0 x 117.4)n/a2017
Sony FE 16-35mm F2.8 GM II Lens19.3(547)3.5 x 4.4(87.8 x 111.5)822023
Sony FE PZ 16-35mm F4 G Lens12.5(353)3.2 x 3.5(80.5 x 88.1)722022

For many more comparisons, review the complete Canon RF 14-35mm F4 L IS USM Lens Specifications using the site's lens specifications tool.

Here is a visual comparison:

Canon RF 14-35mm F4 L IS USM Lens Compared to Similar Lenses

Positioned above from left to right are the following lenses:

Canon EF 16-35mm f/4L IS USM Lens (on a mount adapter)
Canon RF 14-35mm F4 L IS USM Lens
Canon RF 15-35mm F2.8 L IS USM Lens

The same lenses are shown below with their hoods in place.

Canon RF 14-35mm F4 L IS USM Lens Compared to Similar Lenses with Hoods

Use the site's product image comparison tool to visually compare the Canon RF 14-35mm F4 L IS USM Lens to other lenses.

This lens has 77mm threads for mounting filters. While that statement sounds normal, it is unusual for a full-frame lens covering the ultra-wide 14mm focal length to have this extremely valuable feature. The 77mm filter size is common, which makes 77mm filters readily available and also makes sharing filters easier.

Take note that using a standard thickness circular polarizer filter will increase peripheral shading on this lens. Therefore, a slim model such as the Breakthrough Photography X4 is highly recommended.

Canon includes lens hoods with all L-series lenses and, with few exceptions, you should always use them. The EW-83P is the hood model that ships with the RF 14-35mm lens.

Canon RF 14-35mm F4 L IS USM Lens Angle View with Hood

This hood's semi-rigid plastic build lets it absorb some impact, providing physical protection to the camera and lens from bumps. In addition, the hood protruding in front of the lens naturally helps keep dust, water, fingers, limbs, etc., off of the glass.

The EW-83P's petal shape is optimized to block as much light outside of the image circle as possible. That said, zoom lens hoods must be tuned for the wide end of the focal length range, and the ultra-wide 14mm focal length dictates that the EW-83P design be shallow, leaving considerably less than optimal protection at 35mm. Still, this hood offers the front element some protection from impact and, primarily at the widest focal lengths, from bright light. An advantage of this hood shape is easier installation alignment (simply align the small petal to the top), though a round-shaped hood enables the lens to better stand on its hood. The hood's interior is ribbed to reduce internal reflections.

Canon RF 14-35mm F4 L IS USM Lens Case

As a rule, Canon includes a case with their L-series lenses, and the RF 14-35 comes with the Canon LP1219 Lens Pouch. While the drawstring pouch protects against scratches and dust, only the bottom is padded against impact. Consider a Lowepro Lens Case or Think Tank Photo Lens Case Duo for a quality, affordable single-lens storage, transport, and carry solution.

Canon RF 14-35mm F4 L IS USM Lens Cap

Price, Value, Compatibility

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The Canon RF 14-35mm F4 L IS USM Lens is not inexpensive. However, it is a professional-grade lens, and it is considerably less expensive than the RF 15-35 F2.8 model. For those wanting this level of quality, the RF 14-35mm F4 L is a good value.

Canon RF 14-35mm F4 L IS USM Lens on Tripod with Hood

As an "RF" lens, the Canon RF 14-35mm F4 L IS USM Lens is compatible with all Canon EOS R-series cameras. Canon USA provides a 1-year limited warranty.

The reviewed Canon RF 14-35mm F4 L IS USM Lens was on loan from Canon USA.

Canon RF 14-35mm F4 L IS USM Lens Front View on Camera


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The first question on my comparison list was: How does the Canon RF 14-35mm F4 L IS USM Lens compare to the RF 15-35mm F2.8 L IS USM Lens?

In the image quality comparison equalized at f/4, the two lenses are similar overall, with each having some advantages at specific focal lengths. The f/4 lens has dramatically stronger geometric distortion and has stronger lateral CA. The f/2.8 has stronger peripheral shading in most equalized comparisons.

Some of the primary differences between these two lenses stems from the RF 15-35's 2x larger f/2.8 aperture (a strong advantage), and many of those differences are readily apparent in the Canon RF 14-35mm F4 L IS USM Lens vs. Canon RF 15-35mm F2.8 L IS USM Lens comparison. The f/2.8 lens is larger, heavier, uses larger filters (82mm vs. 77mm), and costs significantly more. The f/4 lens focuses considerably closer, taking a 0.38x to 0.21x maximum magnification advantage. Creating the f/2.8 feature requires a significantly higher price tag.

The second question on my comparison list was: How does the Canon RF 14-35mm F4 L IS USM Lens compare to the EF 16-35mm f/4L IS USM Lens, the lens I consider the predecessor model?

In the image quality comparison, the two lenses show rather similar image quality overall. Both lenses have slight advantages in specific comparisons. For example, the RF lens produces sharper periphery image quality at 28mm, and the EF lens is sharper in the center of the frame at 35mm f/4. Performing similarly in this comparison reflects positively on the RF lens — this EF lens is a great performer. The RF lens has dramatically stronger geometric distortion and has stronger lateral CA. The EF lens shows stronger peripheral shading at 35mm f/4 and slightly less at narrower apertures in the wider half of the focal length range.

The Canon RF 14-35mm F4 L IS USM Lens vs. Canon EF 16-35mm f/4L IS USM Lens comparison shows the RF lens slightly lighter and modestly shorter (though slightly wider). Add the mount adapter required for use on a Canon R-series camera, and the EF lens becomes significantly larger. These lenses share many traits, including diaphragm blade count and filter size, but the RF lens's 0.38x maximum magnification spec (vs. 0.23x) and 5.5-stop rated IS system (vs. 4) are notable advantages. The EF lens's considerably lower price tag keeps it in the consideration game.

Let's compare the Canon RF 15-30mm F4.5-6.3 IS STM Lens next.

In the image quality comparison, the 14-35 produces noticeably sharper results. The L lens has less peripheral shading, fewer flare effects, and less geometric distortion (though it too has strong barrel distortion).

The Canon RF 14-35mm F4 L IS USM vs. RF 15-30mm F4.5-6.3 IS STM Lens comparison shows the 15-30 smaller and lighter. The 15-30 uses 67mm filters vs. 77mm and has a higher maximum magnification, 0.52x vs. 0.38x. The L lens is better built, including weather sealing, has fluorine coating, has Nano USM AF vs. STM, has a wider aperture, has 9 aperture blades vs. 7, and has a wider and longer focal length range. The 14-35 is a much better lens but, the big deal is that it costs nearly 3x more.

Use the site's comparison tools to create additional comparisons.

Canon RF 14-35mm F4 L IS USM Lens Top View with Hood


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The Canon RF 14-35mm F4 L IS USM Lens joins siblings RF 24-105mm F4L IS USM Lens and RF 70-200mm F4 L IS USM Lens to form a trio of overall great performing, lightweight, compact, moderately priced, professional-grade lenses that cover a vast majority of the commonly used focal lengths.

As I said at the beginning of the review, the RF 14-35's image quality is excellent (I'll get over the strong barrel distortion aspect), the Nano USM AF system is silent, high-speed, and accurate, and the L-series build quality promises to hold up to the rigors of constant use. Those features, along with the versatility that this lens provides, make the Canon RF 14-35mm F4 L IS USM Lens a great ultra-wide-angle zoom lens choice.

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