Canon RF 24-105L f/4L - A Compromise I'm Willing To Accept
One of two conclusions can be made. Either much of the older masonry and cement work present in Hong Kong isn’t plumb straight, or the Canon RF 24-105mm f/4L IS USM suffers from a horrible case of barrel distortion at its widest focal length. Compared to its predecessor, the Canon EF 24-105mm f/4L IS USM II (which I no longer have, and therefore cannot compare), this new mirrorless version seems to suffer from even more distortion.
Still, I prefer this mirrorless RF version over the relatively less distorted DSLR EF version. And the reason isn’t difficult to see why. Simply put, this new RF version is marginally more compact than the EF version by 0.43” (or 10.7mm) in length. And in achieving this size, Canon did not increase the diameter of the RF version. Just like the EF version, this newer mirrorless version also has the same 3.29” (or 83.5mm) exterior diameter, sporting the same 77mm filter thread.
To some, a fraction of an inch may not seem like much of a reason to consider the RF 24-105. But, when one also considers that the mirrorless version does not require an EF-EOS R adapter, which tags on an extra 0.9” (or 24mm), one can see its benefit in being marginally more compact. Now add the saving in lens size to the difference in size between a full frame Canon DSLR and the full frame Canon EOS-R, and the overall benefit in compactness becomes obvious.
It’s like what James May, formerly of Topgear UK said about cars developed on the Nürbergring. Performance, albeit important, shouldn’t be the singular design focus. And when it comes to lens design, the same is true. Not every lens needs to be designed for the best optical performance. In some cases, a lens should be designed with ergonomics in mind. As counterintuitive as this might seem, a lens that’s comparatively worse can sometimes be significantly better in practice.
There is no denying that a better performing lens renders better image quality. But there’s also no denying that all the improvement in performance comes from an outsized need to bulk up optical design to counter all forms of aberration in documentation - from color fringing to distortion. And when you consider the extra girth you’re carrying around for the sake of image quality, one really wonders if shouldering better optics is worth the backache in recreational use.
Mind you, this is not to say that the Canon RF 24-105 is a tiny lens - because it isn’t. To give you a context of size, it’s a finger width larger than the Leica 75mm f/1.25 Noctilux-M ASPH by 0.62” (or 16mm), which is a gargantuan M-mount lens. With that being said, it’s just about the same size as the Canon EF 35mm f/1.4L II USM - being a hair longer. That means it’s fairly reasonable in size for a variable focal length lens, given that it’s no bigger than a fast contemporary prime.
Even the Sony FE 24-105mm f/4 G OSS is 0.24” (or 6mm) longer than the Canon RF 24-105mm, albeit lighter by 0.8lbs (or 37g), which is the equivalent of a small bag of potato chips (or crisps). But in defense of the RF 24-105, it also comes with a multi-purpose control ring, which the Sony does not have. Personally, I am of the opinion that an on-lens control ring that can be configured to function as an aperture ring is worth accepting a marginal gain in weight.
Forget about Nikon. They don’t seem to have a 24-105mm lens. And as of writing this blog entry, they’ve only announced a 24-70mm f/4 lens - which seems compact at 3.48in (or 88.5mm). That said, I’ve never found a 24-70mm zoom lens particularly useful, in that its maximum focal length never seems far enough in reach for conventional use. Plus, it’s not as if the spread in focal length is especially broad, being a range I can substitute with a couple of steps forward or backwards.
As for the Leica Vario 24-90mm f/2.8-4 Elmarit-SL, it’s so much larger and heavier than the RF 24-105mm that there is no point comparing statistics. Admittedly, the image quality of the Leica Vario is on a different league. But for the sake of recreational use, the Leica Vario really does not make ergonomic sense. And that’s the point that most camera manufacturers seem to be missing. Performance is irrelevant if the lens is too heavy to carry for everyday use.
So, why am I droning on and on about size, and dedicating an exorbitant amount of attention on the 24-105mm focal range, while shirking my duties to conduct a teardown detailing performance characteristics to the extent of marginalizing its relevance? Quite simply, I believe when a lens has hit a threshold of performance standard, it no longer makes sense to gush about it. The Canon RF 24-105mm f/4L is optically a high performing lens, despite some minor flaws.
Besides, the media herd will invariably gravitate towards reporting on all observable performance traits that can be demonstrated online. As such, my input into the scrum isn’t especially necessary in enlightening the world on how this lens performs. But, what I can say about this lens is just how fun it is to shoot. In the span of one hour, I shot over 300 frames and reached a hit rate more than 90%. Frankly, it may be the most relaxing full frame 24-105mm lens I’ve ever used.
For the most part, I shot this lens at modest shutter speeds - even below the law of reciprocity at higher focal lengths - given in-lens image stabilization. This allowed me to document with ease at more modest ISO settings, despite the limitations presented by its maximum aperture of f/4. That said, much of the credit can also be attributed to the electronic viewing experience of the Canon EOS-R, and its remarkable autofocus system in quickly acquiring and tracking focus.
Of course, the real story of the Canon RF 24-105mm f/4 is the restraint that Canon demonstrated in bucking the industry trend towards making optically perfect lenses. In doing so, they would’ve ruined it, by countering the flaws that everyone typically overlook in recreational use, with heavier corrective measures. So if you happen to be that special few where straight lines and backlighting must be captured without optical aberration, this lens isn't for you.
But for everyone else in need of a reliable lens for everyday use, the RF 24-105 is truly a practical choice. It’s wide enough at 24mm to document in tight spaces, and it’s tight enough at 105mm to extend sufficient reach to frame a subject from 50ft (or 15m) away. And compared to a typical M mount lens, it can shoot closer by 10in (or 0.25m) to a minimum distance of 17.75in (or 0.45m). In other words, it can be used for close up foodie pictures from either extremes in focal length.
Moreover, the RF 24-105mm f/4L offers five stops in image stabilization, weather sealing, and that multi-purpose control ring - all in that relatively compact package. And when paired to the Canon EOS-R set to face detection, with the autofocus point snapping back to center, the RF 24-105mm is effortless in acquiring and tracking focus. The only documentary disadvantage exhibited by this lens is its speed in low light. But, it’s nothing that can’t be solved by the EOS-R’s high ISO ability.
So after shooting this lens for quite some time on the Canon EOS-R, I believe the most effortless way to shoot it effectively is to set the camera at auto ISO and shutter priority - which admittedly I didn’t do on this photowalk. Given a maximum aperture at f/4, most everything in-frame close to the focal plane of the subject will reasonably and perceptibly be in focus, at the wider end of the focal range for most conventional documentary situations.
Since you’re not going to be winning anyone’s heart at maximum aperture with subject isolation, you might as well configure your shooting objective to freeze motion for the sake of optimizing documentary precision - despite the obvious issues of barrel distortion and chromatic aberration. That said, the issue of distortion appears to improve at tighter focal length - well kind of, while color fringing can easily be resolved in post with editing software.
Personally, I don’t believe it makes much sense to stop down on this lens, unless you’re under the bright noonday sun, or if you’re trying to get a group shot with everyone staggered widely across multiple focal planes. In my opinion, the sole purpose of this lens, like its EF predecessor, is to get the shot. To that end, the Canon RF 24-105mm f/4L does not make excuses nor does it pretend to be anything else. All it does is do what it’s suppose to do - no more and no less.
Frankly, I enjoy using this lens. It’s not perfect. But, that’s what makes it perfect - imperfection. In the end, this lens is a compromise - and it’s one I’m willing to accept for everyday use. That said, I’m truly curious about the Canon RF 28-70mm f/2L USM. It’s probably a lens I’ll never lug around for fun. Still, I suspect it’ll somehow find its way to my heart for professional application.
Images have not been edited in Adobe Lightroom beyond simple tweaking in exposure no less than ±0.5 stops, unless mentioned under the captions.
Some would say that I goofed for not stopping down. But honestly, this lens is going to perform reasonably well at lower aperture settings. That said, I think I’ve been too preoccupied with not depending too much on high ISO that I admittedly made a rookie oversight.
Below is an example of chromatic aberration at high magnification.