Canon RF 100mm F2.8L Macro IS USM review - hidden depths

Two-minute review

(Image credit: Rod Lawton)

The Canon RF 100mm F2.8L Macro IS USM is the only "official" macro lens in the Canon RF lens lineup. The brand does make some other macro-enabled primes, including the RF 24mm, RF 35mm and RF 85mm f/2 lenses, but these achieve a maximum magnification ratio of 0.5x, or half life size; so while this might be plenty close enough for many users, they're not true 1:1 macro lenses.

The RF 100mm F2.8L Macro IS USM doesn’t stop at life size reproduction, however; it goes to a full 1.4x magnification. That means you can fill the frame with an object just 26mm wide. And that isn't its only interesting feature.

Half way along the barrel is an intriguing "SA", or Spherical Aberration, control ring. This shifts optical elements within the lens to adjust the appearance of bokeh, both in front of and behind your main subject, and can also introduce a soft-focus effect.

The SA (Spherical Aberration) adjustment is unlocked via a switch on the underside of the lens. (Image credit: Rod Lawton)

It isn't immediately obvious how you're supposed to use this control, since it’s locked at its center position. In fact, there’s a switch on the underside of the lens to unlock it, which is easily missed. This is one lens where it's actually a good idea to read the manual!

This bokeh control is aimed more at portraiture and longer shooting distances; indeed, Canon does seem keen to push this as a "portrait" lens as well as a macro lens. It’s an interesting idea, but then it leaves you wondering whether the Canon RF 85mm f/2 Macro IS STM might be better, being a stop faster and far cheaper, too. You might say the 100mm is a macro lens first and portrait lens second, while the 85mm is the other way around.

I only had the RF 100mm F2.8L Macro IS USM for a short time, so I concentrated on its macro capabilities.

These are pretty formidable. It’s hard to make any sensible comments about edge sharpness wide-open with close-ups because it’s near-impossible to find a subject flat enough to test it on – and to get it perfectly perpendicular to the camera. Photographing a framed vintage "butterfly wing" picture reveals another macro photography issue: objects with layers of paint and textures, especially those under glass that may have dust or fibers on its surface, are actually three-dimensional.

Here's one of my test subjects, a very old "butterfly wing" picture just over 2-inches across. (Image credit: Rod Lawton)

This is a magnified section close to the Canon RF 100's 1.4x maximum. At this magnification, even at an aperture of f/8, its hard to keep all the strata of this object in focus. (Image credit: Rod Lawton)

This was taken at f/2.8, so the depth of field is extremely shallow – but this can suit many subjects. (Image credit: Rod Lawton)

At f/16, much more of this narcissus is sharp; but if you want objects with depth to be properly sharp from front to back, you'll need to resort to focus stacking. Small apertures alone won't do it. (Image credit: Rod Lawton)

The engraving on this old cigarette case, and all the tiny blemishes and scratches around it, are resolved extremely crisply – although the lens was so close to the case at this point that I had to shoot at a slight angle to avoid shadows and reflections from the lens in the polished metal. (Image credit: Rod Lawton)

Only the most ambitious, bokeh-loving macro fan would want to shoot wide open at these distances. You’re more likely to want to shoot at f/11-f/22, and the RF 100mm F2.8L Macro IS USM produced crystal-clear detail that was difficult to fault.

However, while you might think that a 100mm lens should offer plenty of working distance between yourself and your subject, that isn't the case here. At its closest shooting distances, the front of this lens is close enough to your subject to cast a shadow or give unwanted reflection on shiny surfaces. A skilled macro shooter could fix this easily enough with good lighting and choice of angles, but it was still a bit unexpected. 

This lens is weather-sealed and has a fluorine-coated front element, so you won't have to worry too much about wet outdoor conditions. (Image credit: Rod Lawton)

If you shoot wide open at f/2.8 then you can achieve good subject separation and background blur – although, with this subject we could have got just as close with one of Canon's regular "macro" primes. (Image credit: Rod Lawton)

You can also use this lens outdoors on a range of subjects, where its weatherproofed design and fluorine-coated front element should shrug off rain and dew. The lens also has image stabilization built in – although, as Canon admits, the effectiveness diminishes the closer you focus. 

This isn't necessarily a fault with the stabilization, but an issue with handheld macro photography. If you can’t keep the camera perfectly steady, even the tiniest fore-and-aft "drift" will throw your subject out of focus between half-pressing and fully pressing the shutter release (switching to Servo AF mode can be an effective solution!).

The RF 100mm F2.8L Macro IS USM’s Dual Nano USM autofocus seemed pretty quick at normal shooting distances, doing a reasonable job of tracking the eyes of our pet Dachshund. However, on occasion it got a bit lost switching to ultra-close subjects. It has a focus limiter to help with this, and you can also use manual focus to get it in the right ballpark first. In fact, manual focus works especially well here. The focus ring is smooth and precise, and there’s a real focus "snap" in the viewfinder to show you when the focus is correct. 

Canon says this lens has suppressed focus breathing, which should be especially useful for filming where you want to use focus pulls.

The Dual Nano ISM autofocus kept up pretty well with our canine subject, and the combination of a long focal length and f/2.8 aperture produced good background blur and separation. (Image credit: Rod Lawton)

This is a nice lens to use, if rather long. The SA control seems a slightly odd choice for macro work; I guess it's designed more for portraits and larger product shots. It’s good to have a single lens that can do a few jobs, so it’s easy to see how the RF 100mm F2.8L Macro IS USM could create a kind of "product" lens category of its own.

Best of all, it isn't hugely expensive for an own-brand macro lens, especially one that can focus closer than rivals and has IS built in.

Canon RF 100mm F2.8L Macro IS USM Price and release date

(Image credit: Rod Lawton)

The RF 100mm F2.8L Macro IS USM was announced in April 2021 and is now widely available. It typically costs around $1,099 in the US and £1,369 in the UK. However, if you don’t mind manual focus – and you’re not interested in the SA bokeh control – then you can get the Venus Optics Laowa 100mm f/2.8 2X Ultra Macro APO lens for around half that, and with even higher 2x magnification.

Should I buy the Canon RF 100mm F2.8L Macro IS USM?

(Image credit: Rod Lawton)

Buy it if…

Don’t buy it if…

How I tested the Canon RF 100mm F2.8L Macro IS USM

I tried out the RF 100mm F2.8L Macro IS USM in a variety of situations to test its performance, handling and image quality. One session was spent shooting a family pet to see how well the Nano USM autofocus could keep up with my EOS R8’s excellent AI subject tracking, while another was spent out on the coast, shooting a variety of subjects from driftwood to sea spurge.

I also spent some time testing this lens with typical close-up subjects including a challenging "butterfly wing" picture, some just-open narcissi, and the engravings on a vintage WW1 cigarette case. These were taken using a tripod, the 12-second timer on the camera, and electronic shutter mode.