Intro

The Canon RF 14-35mm f4L IS USM is a compact, ultra wide zoom for the EOS R mirrorless system and corrected for full-frame bodies. Announced in June 2021, it’s the widest lens in the RF system to date, and extends the range available in smaller, lighter and more affordable f4 models. Note this lens will not work on EOS DSLRs or EOS-M mirrorless cameras, it’s designed only for EOS R cameras with their RF lens mounts. In my full review I’ll show you how it compares to the larger, heavier and more expensive RF 15-35mm f2.8L as well as showing some comparisons against the budget RF 16mm f2.8. It’s all in the video below, but if you prefer to read a written version, keep scrolling for the highlights!

Canon’s first ultra-wide lens for the EOS R system was the RF 15-35mm f2.8L, launched in August 2019 and seen here in the middle. Priced at $2400 and weighing 840g, it’s a heavyweight in both cost and heft. The RF 14-35mm f4L, here on the right, arrived almost two years later, providing a smaller, lighter and more affordable alternative, costing $1700 and weighing 540g. 

Both are however premium zooms, so Canon followed them up with the budget-oriented RF 16mm f2.8 in September 2021. At just $299 and weighing 165g, this fixed-focal lens is a fraction of the size, weight and price of the L-zooms, and brings ultra-wide goodness to a broader audience. 

While this review will concentrate on comparing the two L-zooms, I’ll also include a selection of side-by-side results against the budget 16mm to show how they differ in practice, as it could provide exactly what you need with a significant cost-saving. If you find these direct comparisons with real-life subjects useful, please consider subscribing to my channel, thanks!

Measuring 84x100mm and weighing 540g, the RF 14-35 f4L is a fairly compact zoom with optical stabilisation, dust and moisture resistance and a 77mm filter thread.

At 89x127mm and weighing 840g, the RF 15-35 f2.8L is wider, longer and over 50% heavier. Like the f4L model, it also sports optical stabilisation as well as dust and moisture resistance, but the larger aperture demands bigger 82mm filters.

From the side you can see the controls starting with a switch for auto or manual focus and another to turn the stabilisation on or off; note if your EOS R body has built-in sensor-shift IBIS, this switch will also switch it on or off as the optical lens IS currently works alongside it.

The first ring operates the zoom, with the lens at its shortest physical length when set to around the 20mm focal length. As you adjust it to the 14 or 35mm focal lengths, the barrel extends a little by about 9mm.

Next is a smooth manual focusing ring, motor-assisted like all native Canon RF lenses, followed by a customisable clicky RF control ring at the end. As a member of the L-series, the lens is branded with a red ring at the end and supplied with a petal lens hood.

For comparison here’s the RF 15-35 f2.8L from the side where you can again see it’s a heftier proposition, and in use you’ll really feel the difference in your hands and in your bag. Once again there’s switches for focus and stabilisation, followed by the zoom, manual focus and custom control rings. Note how the focus and especially the zoom rings are wider on the 15-35 than on the 14-35, although they’re similarly smooth to operate. And here it is with the supplied lens hood.

Already the zooms enjoy a number of key benefits over the budget RF 16mm 2.8, beyond the obvious ability to zoom and having optical stabilisation. Like the budget RF 50 1.8 before it, the 16 2.8 has only one ring with a switch to set it between manual focus and custom control. Annoyingly, both these lenses also require you to enter a camera menu to select Manual Focus, rather than simply flicking the AF / MF switch on the higher-end models. 

There’s also no weather-sealing, nor any hood supplied in the box, and while the 43mm filter thread is much narrower than the L-zooms, it’s a fairly uncommon size that can be hard to find filters for, at least without stepping-up to bigger ones.

Ok now for my tests and I’m going to start with autofocus with the 14-35 on an EOS R5 at 14mm f4 and single AF mode where you can see the lens snapping into focus almost instantly.

Next with the lens zoomed to 35mm and still wide-open at f4 and again you’ll see the focusing snaps-on pretty much the instant I push the shutter release button. This may be similar in speed to the RF 15-35, but both are visibly quicker – not to mention quieter – at focusing than the RF 16, both of which you can see in action in my respective reviews of each. I’ll show you movie autofocus in a moment.

Next for coverage, especially at the wide-end as that’s what really differentiates these three lenses, and while the 14 genuinely delivers the widest field of view in the native RF series to date, it does rely on fairly significant Distortion Compensation applied either in-camera for JPEGs or using profiles when converting RAW files. Whether this bothers you is a personal choice, but I’ll briefly show you what’s going on behind the scenes.

First, here’s what you’ll get when shooting JPEGs with each lens using the default settings, starting with the RF 16mm which has Distortion Compensation automatically applied for in-camera JPEGs. You can’t turn this off for this lens.

Next for the RF 15-35 at 15mm which by default has Distortion Compensation disabled as it’s already pretty well-corrected in this regard. Not perfect as you’ll see in a moment, but the best of the three lenses here.

And finally the 14-35 at 14 where like the 16, Distortion Compensation is applied automatically for JPEGs. As you can see, each lens is capturing a progressively broader field of view for JPEGs out of camera as you’d expect, even after compensation has been applied to the 16 and 14-35. Once again, the 16, then the 15-35, then the 14-35.

Next for some RAW comparisons, starting with the 14-35 at 14mm with the lens corrections applied by the profile in Adobe Camera RAW, where the coverage is actually a tad wider than the in-camera JPEG corrections – a nice bonus for RAW shooters, but now let’s switch to the same RAW file with lens profiles disabled and you can see exactly what image is being delivered by the lens to the camera before any corrections.

The uncorrected version is noticeably wider, but suffering from barrel distortion as well as vignetting in the corners – the latter is actually the edge of the imaging circle itself. Switching back and forth between the corrected and uncorrected RAW file illustrates what’s going on behind the scenes with the 14-35, but as you’ll see even with the crop applied during compensation, it remains the widest of the three here.

Next up the 15-35 at 15mm and you’re looking at a RAW file with the full correction profile applied in Adobe Camera RAW where the result is roughly similar to the out-of-camera JPEG earlier. 

And now for the RAW file with lens profiles disabled where you’ll see the lens capturing a slightly wider field with a little barrel distortion and mild vignetting, but it’s nowhere near as severe as the 14-35. Switching between the RAW files processed with and without lens compensations applied illustrates the difference between them is much more mild, unsurprisingly confirming the 15-35 as the best-corrected of the three lenses here.

To better illustrate the geometric distortion that’s being corrected by the profiles, here’s a shot of my wobbly garden wall with the 14-35 at 14mm. It’s an out-of-camera JPEG where the distortion compensation has been automatically applied, and other than some pointing work needing to be done on the wall, it’s looking fairly normal.

But now for the RAW version where I’ve processed it without compensation to show what the actual optics are delivering to the sensor. There’s significant distortion here.

For comparison though, here’s the uncorrected RAW version from the RF 16mm which has even more extreme distortion, although it is of course a much cheaper non-L lens.

And finally for the RF 15-35 at 15mm, again the RAW version with compensation disabled, where it too is showing some barrel distortion, but far less than the other two. This again confirms it as the best-corrected of the three to start with, although again unsurprising given its size, weight and price.

Software corrections have become part of modern lens design and allows smaller, lighter, cheaper or more extreme options to be made. Purists may prefer an entirely optical solution, but this will inevitably result in a larger, heavier and more expensive lens. Personally speaking I’m at peace with lens profiles as it’s all about the end-result, rather than the journey to get there, although it is important to remember the more pixel wrangling you need to do to get an image into shape, the greater the hit on the resolution will be. You’ll inevitably notice this most in the corners, so the question becomes what is acceptable for you. 

To help you decide, I’ll now compare the sharpness of the two L zooms for my distant pier scene, angled so that details run into those corners. I always say this, but these outdoor comparisons of distant subjects with multiple lenses across various focal lengths take a lot of work, but I feel are essential in a lens review.

StaLet’s start here with the 14-35 f4L at 14mm f4 on the EOS R5 body. These are all JPEGs out of camera with the default settings, so that’s distortion compensation on for the 14-35 and off for the 15-35. And if you’d like to see how the budget RF 16 compares, check out my separate review of that lens.

Taking a close look at the center of the frame, which is where the lens was focused, reveals fine details out of the gate with no significant benefit to sharpness or contrast as you stop-down.

Heading out into the corner shows the 14-35 becomes a tad softer than in the middle of the frame at f4, but again this is when the lens is focused in the centre and the result is still very respectable. If I close the aperture one stop to f5.6 and again to f8 there’s a fractional improvement in sharpness, but nothing significant. So you’re getting close to the maximum performance from this lens with it wide-open.

Let’s return to the close-up of the centre of the 14-35 at 14mm f4 and compare it against the 15-35 f2.8 on the right, here at 15mm f2.8. I’d say they’re both looking quite similar here, although once their apertures are matched, the 15-35 on the right is arguably a tad superior if you’re pixel-peeping. Not much in it though.

Now let’s compare the corners of both lenses at their widest focal lengths and maximum apertures, and I’ve shifted inwards a little on the 14-35 frame to match the details as it captured a slightly wider field of view. In this comparison you’ll see the 14-35 at f4 on the left slightly out-performing the 15-35 at f2.8 on the right, but close the latter one stop to f4 and I’d say it takes the lead in ultimate detail. This edge is maintained as both their apertures are matched and closed further. This could be due to superior optics, less digital compensation, or more likely a combination of both.

Ok, next for the 14-35 f4L roughly mid-way through it’s range at 24mm and wide open at f4, and again focused in the centre of the frame. Taking a close look at the middle again reveals sharp details and only minor boosts to contrast if you stop down further. 

Moving out to the corner of the f4 image, the 14-35 is managing to maintain sharpness pretty well at the 24mm focal length, even with the aperture wide open. Closing the aperture to f5.6 and then to f8 doesn’t seem to make any significant improvements.

Returning to the middle of the frame with the 14-35 at 24mm f4 on the left and the 15-35 at 24mm f2.8 on the right, I’d say they’re looking pretty similar. As I match the apertures and gradually stop down, I’d say the 15-35 enjoys a mild benefit in contrast, but it’s subtle. Both are performing well here.

Back out to the corner where we can now directly compare the two lenses with matched coverage, there’s a little softness on the 15-35 perhaps due to coma when it’s wide-open at f2.8 which remains just visible when closed to f4, but as both lenses are closed to f5.6 and then f8, the 15-35 becomes crisper overall with finer details. So if you can close the aperture a little, the 15-35 will give you better corner performance at 24mm, perhaps again due to less pixel-wrangling.

And finally for the 14-35 f4L at its longest focal length of 35mm and wide-open at f4. Taking a close look in the middle of the frame, where the lens was focused, again shows very crisp details. Closing the aperture down won’t get you any sharper details but may improve the contrast a little.

As you move out into the corner, the 14-35 remains respectably sharp at its longest focal length, and even wide-open at f4 there’s little to complain about. This time stopping down to f5.6 and then f8 does little to improve what’s already excellent performance out of the gate.

Returning to the middle of the frame with the 14-35 at 35mm f4 on the left and the 15-35 at 35mm f2.8 on the right again shows a very similar-looking result out of the gate, with little benefit to stopping down other than a mild boost in contrast.

Heading back out to the corners with both lenses at 35mm and set to their maximum apertures reveals a little softness to the 15-35 on the right at f2.8, but once closed to f4 to match the 14-35, the overall detail becomes similar. As their respective apertures are closed further, I’d say the 15-35 on the right takes a mild lead in overall crispness and contrast, but they’re fairly close here.

Ok next for a quick portrait test to compare subject sharpness and background rendering, starting with the 14-35 at 35mm f4. Taking a closer look shows bitingly-sharp detail around my eyes and some blurring in the background, although unsurprisingly at 35mm f4 there’s never going to be much separation. So how much difference can you expect from the 15-35 with its extra stop of aperture? 

Here’s the full 14-35 image once again and now for comparison let’s switch it out for the 15-35 at 35mm f2.8 from the same distance. There’s a little more blurring, but not a huge difference when viewing the full image.

Taking a closer look with the 14-35 at f4 on the left and the 15-35 at f2.8 on the right reveals the differences in rendering. The bokeh balls are definitely larger, but I’d say with more defined outlining which is not always desirable, although both lenses are undeniably pin sharp on the focused areas. Swapping the f2.8 version on the right for one taken at f4 roughly matches the size of the blurring from the 14-35 on the left, but I’d still say there’s a softer style to the 14-35 which I personally find preferable.

To see the differences in rendering at close range with bokeh balls, here’s the 14-35, again at 35mm f4 near to its closest focusing distance. There’s very mild textures within the bokeh balls but it’s not distracting and there’s not much outlining either. 

Let’s now switch that image out for the 15-35 at 35mm f2.8 where you’ll see the subject is a little more magnified at the same distance, and the bokeh balls are unsurprisingly larger. But as we saw in my portrait example, they also have quite defined outlining which may or may not be to your taste.

Here’s the 14-35 on the left at f4 and the 15-35 on the right at f2.8 where their differences in rendering style is quite obvious. Do you have a preference? Now let’s swap-in the 15-35 at f4 on the right to match the aperture of the 14-35 on the left, and finally them both closed to f5.6.

At the other end of the aperture scale you can achieve nice crisp diffraction spikes with the 14-35, here at 14mm f22, although as always you’ll need to keep the front element and the sensor itself meticulously clean to avoid marks. And for good measure, here it is at 35mm f22.

Ok now for video performance, starting with autofocus on the 14-35 at 14mm f4 on the EOS R5 where it smoothly racks between near and far without issue. And now for the lens at 35mm f4 where again the R5 has no problem refocusing it between near and far without overshooting. The focusing is also very quiet.

And now for a quick face tracking test, first with the 14-35 at 35mm f4, again on the EOS R5 which tracks me no problem. And for comparison the 15-35 at 35mm f2.8 where again the tracking is fine and you can see the differences in rendering from the earlier stills.

While we’re on the subject of focusing, how about breathing when the magnification can change as you refocus? Here’s the 14-35 at 14mm focusing from infinity to the closest distance and back again to infinity. And for comparison, the 15-35 at 15mm, again focusing from infinity to the closest and back again. Both lenses actually increase their field of view or become wider as they focus closer, but the 15-35 showed a bigger variance here.

Next here’s the 14-35 at 35mm, again focusing from infinity to the closest distance and back again where again the image becomes wider as you focus closer. And likewise for the 15-35 at 35mm, again focusing from infinity to the closest distance and back again. So both lenses exhibit changes in magnification as they focus through their ranges.

And finally a vlogging test as ultra-wide angles are always popular for this kind of thing, starting with the 14-24 at 14mm f4 with IBIS in the R5 and optical stabilisation in the lens working together – there’s no way to turn off one or the other.

Next the same lens and camera but this time with additional Digital movie stabilisation applied, where there looks like a mild crop but some of that warping at the edges has been reduced. This works alongside IBIS on the Canons and at the moment you can’t choose one or the other if your body has IBIS.

And now with Digital movie IS set to Enhanced where there’s a more significant crop, making the 14mm look more like a 24 at arm’s length here. But for handheld walking and talking, the result looks the best of the three examples.

Let’s go back to the IBIS and optical IS version only before switching it for the 15-35 at 15mm f2.8, so a fraction less wide, but an extra stop of aperture brighter, allowing slightly greater subject separation here, although it’s not a huge difference and both lenses suffered from warping at the edges when stabilised with IBIS and IS on the R5 when I was walking with them.

Your mileage will of course vary, so here’s one more comparison, still handheld, but much more gentle, starting with the 14-35 at 14mm f4, where those warping artefacts have mostly been banished. And now for the 15-35 at 15mm f2.8 again showing slightly more blurring behind me. In my tests with different systems I’m finding digital stabilisation alone is working best for walking vlogs, so I hope Canon allows us in the future to select exactly which stabilisation techniques are applied, rather than just forcing them all simultaneously.