Canon RF 100-500mm f/4.5-7.1L Lens Review

bythom canon 100-500mm

What is It?

The RF 100-500mm f/4.5-7.1 lens is the first extreme telephoto zoom in the Canon RF lineup, and to a large degree, a replacement for the EF mount's 100-400mm.

Even a cursory examination reveals a lot of interesting features: three-mode lens-based IS, an extra ring, a range limiter switch, and even a little window on the lens hood that opens to let you manipulate a circular polarizer mounted on the lens. 

The f/4.5-7.1 aperture on a telephoto zoom seems a little more restrictive than we're used to (f/4-5.6), but the lens also compacts down into 8" long and 3.7" diameter, which lets it pack really easy in your bag for a 500mm reach.

Build-quality is Canon's usual L-type build, with a weather-resistant construction and a very solid feel. The front element is fluorine coated for resistance to water and dust. 

As usual with Canon telephotos, the lens is an off-white with black focus and zoom rings. While the lens extends over 3.5" (90mm) to get to 500mm, there's no slop at all to the inner barrel when extended. The rotating, removable tripod collar locks down solidly, as well, with no give at all when properly set. Unfortunately, Canon hasn't discovered we're all going to end up putting Arca-style plates on the foot and instead only gives us the usual 1/4" threaded socket along with an alignment hole.

Weight is a reasonable 48.3 ounces (1370g), given all we have going on here. 

Focus is via a fast and virtually silent motor, and does not rotate the front element. 

The extra control ring at the rear of the lens has subtle click detents, and it can be set for exposure compensation, shutter speed, aperture, ISO, flash exposure compensation, AF method, white balance, and more. That subtle clicking is actually quite good, as it means that you can set something via the ring and not easily dislodge it to another setting. I prefer this to the way Nikon's "third ring" is just freewheeling.

The zoom ring is marked at 100mm, 135mm, 200mm, 300mm, 400mm, and 500mm. The maximum aperture changes as follows:

  • 100mm — f/4.5
  • 150mm — f/5
  • 250mm — f/5.6
  • 360mm — f/6.3
  • 475mm — f/7.1

That progression is a little more aggressive than I'd like to see. I found it rare that my maximum aperture was less than f/5.6 in my use of this lens, as I was rarely below 250mm. Your mileage may vary.

In terms of optics, Canon gave us the usual smorgasbord with 20 elements in 14 groups, with 1 Super UD and 6 UD elements to control aberrations. Filter size up front is a friendly 77mm, and the front element has fluorine coating to help with keeping it clean. Canon supplies the reversible ET-83F lens hood with the lens, and that lens hood has a nice little window you can open to get access to any filter that needs rotation (e.g. circular polarizer). 

Minimum focus does change with focal length:

  • 100mm — 35" (0.9m)
  • 500mm — 47" (1.2m)

I don't judge that to be particularly problematic, especially since we end up at 1:3.3 maximum magnification at 500mm, which is getting near macro range. 

Nine blades form the aperture diaphragm in the lens.

The lens and all the supplied accessories is made in Japan and lists for US$2700. The lens is compatible with the RF1.4x and RF2x converters, but only from 300-500mm for some reason.

Source of the reviewed lens: six-week loan from B&H

Canon's Page for the 100-500mm f/4.5-7.1

How's it Handle?

For the most part, this is a well-designed lens that, for its focal range, balances nicely on the R5/R6 bodies. The focus ring is not the freewheeling type that Nikon uses, and I prefer that. The switches are all rock solid: they don't dislodge to a new position with bumping; they require real user force to move them.

I had a few nits, though:

  • The lens cap kept falling off the lens as I mounted, unmounted the lens hood. Moreover, I could get the hood mounted slightly "off" pretty easily, which is what often triggered the cap problem as I'd touch the cap while twisting the hood. I don't judge this to be a big thing, but I'm someone who works in the heat of battle a lot. Going slow and paying attention, I didn't have the problem. Working fast and not paying as much attention, I popped the lens hood from time to time.
bythom canon smoothtight
  • Instead of a focal length lock, we have a Smooth/Tight ring. You definitely will find the lens extends when pointed downwards when in the Smooth position. The Tight position isn't a lock, though. I'm not sure if I like this or not. In Smooth, the ring is definitely smooth, though with a minor "hitch" near the telephoto end on my sample. It is true that if you put the lens away at Tight so that it didn't accidentally extend, if you picked up the lens in the heat of battle (that again?) and went to zoom it, you could zoom it, though it'll be very stiff and resisting you. Overall, the zoom ring goes about 120° from minimum to maximum.
  • The foot on the tripod collar seems a little short to me. There's not enough there there to comfortable walk with the lens while holding it by the collar. 

Still, the lens is classic Canon, and Canon users won't have any issues with it. If you've used the EF 100-400mm and liked it, you may even like this RF version better. 

How's it Perform?

Focus: Fast and virtually silent. The R6 I was using this lens on is very snappy in its focus performance, and this lens had no problem keeping up.

Sharpness: at 100mm, the center is excellent, but the corners are fair at best. Stopping down to f/8 brings the corners up to very good. At 500mm, the center is very good, and again the corners are only fair. Stopping down to f/11 improves both center and corners to the point where I'd call the results very good across the frame.

This lens has some clear coma and astigmatism, though it's not particularly strong. However, this helps explain the poorer corner results.

bythom US PA LVNC Oct18-2020 R6 0132

Chromatic Aberration: I was surprised to see clear green/magenta edging on test chart results. On many lenses, lateral CA is "masked" due to the use of a lot of ED-type glass, but this lens had clearer fringing than I'm used to, though not necessarily wider. This was most evident at 100mm. At 200-300mm the lens produces less lateral CA to the point where I probably wouldn't correct it, but the edge coloration returns by 400mm and peaks again at 500mm. If the CA bothers you, stopping down does have a clear impact on it. Also, Canon's lens corrections do a good job in removing it.

I was also surprised to find a fair amount of longitudinal CA in the lens. Generally slower zoom lenses don't tend to show much, but it's clearly there wide open with this lens. Not objectionable, at all, but still, something that you may find a problem with certain imagery.

Vignetting: there's clear and dramatic vignetting of nearly two stops when shooting wide open. Unlike a lot of zooms I see, this one seems more consistent across its focal range. You need to stop down two stops to essentially remove vignetting to what I call fully acceptable levels.

Bokeh: you usually don't talk about bokeh on an f/7.1 lens, but this is a long telephoto zoom, and when shooting medium distance animals with a far background, you definitely will see how the out of focus areas render. This lens has a clear outer ring to OOF highlights, and that ring is fringed with CA color. I also see onion-skinning. What I don't see is much in the way of cats eye problems as you move to the corners. Circles do become elliptical at the edges and corners, but not objectionably so as I've seen in some lenses. Note that EFCS and IS can impact the bokeh, particularly in mid-range OOF.

Normally, we'd call this kind of bokeh performance mediocre, but in looking at scenic backgrounds (e.g. bush), I'm not finding that the problems I identify above really come into play much. An out of focus background for landscape tends to render pleasantly soft with only a small amount of "busy-ness". Where I find that the busy attributes start to be more defined is in cityscape images where the background isn't completely thrown out of focus.

Final Words

The RF100-500mm f/4.5-7.1L isn't a perfect lens, but it's a really solid choice for those that need flexibility in the telephoto range. Generally we mostly worry about the central region with long telephoto photography, and there's not much to complain about there. If you can manage to stop down a bit, it would difficult to find a lens that performs better in the center, but even wide open I find this lens quite good.

The corners, though, are the indicators of this lens' weakness: coma, astigmatism, lateral chromatic aberration, and a bit of what looks to be non-linear distortion. At this price level I'd be more comfortable had Canon done more to address those corners. That's particularly true because to improve the image outside the center of the frame, you're going to stop down, and you're already running slow apertures to start with, especially once you're out past 350mm.

With some past Canon cameras, shooting at f/8 or f/11 would force ISO boosting into a range you probably didn't want to shoot in. Fortunately, the R5 and R6 seem to be better at high ISO work than previous Canon RF cameras. On an RP with its older sensor, I'd judge the 100-500mm f/4.5-7.1L as a "fair weather" lens: you really don't want to be at ISO 6400 and f/11 with the RP. 

The obvious comparison goes to the older EF 100-400mm f/4.5-5.6L for Canon DSLRs. That lens was a classic Canon lens and in the bag of many photographers, even pros. My memory of that lens—it's been several years since I used one—is that it was a little better behaved at the extremes (focal length, corners). But it also doesn't go to 500mm, and I don't think it tolerates the TCs quite as well as this new lens (I need to test that hypothesis, but had no way to do that with the short term loan I was working with). 

I have little doubt that the RF100-500mm f/4.5-7.1L will become a staple in most RF mount users' bags. It's quite good, just not great. That's one of the prices you pay for flexibility (zoom) over just plain reach (focal length). 

I have no qualms recommending this lens for the R6 user. That's how I tested the lens, and  I found the pair to be an excellent match. I could see myself shooting daylight sports and wildlife with the combination without worry. Twilight? I'd be teetering right on the edge at 500mm, I think, but still happy. I can't speak to the R5 as I haven't shot with the combination yet. All that extra resolution on R5 is going to pull that coma, astigmatism, and lateral CA into more pixels, and I'd need to analyze that more closely to be comfortable in saying anything conclusively. 

Recommended (2020)

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