With the release of the ground-breaking EOS R5 and R6 full-frame mirrorless camera bodies, Canon unequivocally released a range of professional RF lenses that match and enhance the performance of these bodies. What caught the attention of most wildlife photographers was the introduction of the first 3 telephoto lenses in the RF arsenal suitable for wildlife photography.

This article will serve as a user review of the Canon RF 100-500mm f4.5-7.1 L IS USM with slight comparisons to the Canon EF 100-400mm f/4.5- 5.6L IS II USM. As always, do head over to other reviews on the net if you are looking for a deeper dive into technical specifications of these lenses.

The EF 100-400mm f/4.5- 5.6L IS II USM has been in the market and is well loved by professionals all over the world, its performance and image quality it produces is unparalleled in the market of Telephoto zoom lenses. The RF 100-500mm has in fact been called the successor of this lens but with an RF mount to suit Canon’s new R system.

Needless to say, if you caved in and upgraded to the R5/6, you would have a choice between these two lenses, the 100-400 with an adaptor, or the native 100-500. We all know that EF lenses seamlessly work with the R bodies with the adaptors, so is it worth the upgrade? I mounted the lenses on an EOS R6 to find out.

(Left) Canon EOS 5Ds R + Canon EF 100-400mm L IS II Lens & (Right) EOS R5 + Canon RF 100-500mm L IS Lens

Let’s first talk build quality. As with any Canon L lens, you can expect superior build quality (weather proofing) and performance. Likewise, you can expect to pay a premium. Aesthetically, the two lenses are very similar and use the same 77mm filter thread. The 100-400 is the girthier/stubbier lens of the two (94 x 193mm) as compared to the 100-500 (93.8 x 207.6mm), However, albeit the additional 100mm, the RF lens comes in at approximately 300g lighter at 1365g compared to 1640g. Thus, in terms of ergonomics and regular usage, both lenses are pretty much the same.

Other changes include the tripod collar, tightening ring, button placements and the removal of the display. If I could change one thing about the RF lens would be to increase the size of the focus ring and make it ‘less smooth’. In certain situations where autofocus struggles (thick foilage etc), I tend to use manual focus override to get precise focus on my subject. The ring compared to the EF 100-400 is so smooth (disclaimer: I do not mean that the ring is loose) that being very precise proved to be a challenge and it will take some time getting used to. Improving on the removable tripod collar was a nice touch as it sturdier than the 100-400mm, providing even more stability.

As with all RF lenses, the RF 100-500 comes with a diamond-textured control ring located right behind the tripod collar. This ring grants added ease of switching exposure settings and is customisable. Out of the box, this function has to be enabled in the camera’s “Custom Functions” menu. You will be greeted with the options to change your ISO, Shutter Speed, Aperture and Exposure Compensation. The options with the downward arrow indicates that changing your settings with the ring will only work if the shutter is half pressed, sort of acting like a ‘safety net’. The ring has several clicked-stops to indicated incremental changes and is slightly audible.

<Mugimaki Flycatcher (Ficedula mugimaki)>
EOS R6 + RF 100-500mm f/4.5-7.1L IS USM Lens
1/200s, ISO 800, f/7.1

Alright, let’s address the elephant in the room, what about that “7.1” aperture? Canon probably sacrificed on the aperture in order to make the lens lightweight and compact. Personally, I would rather have the lens at f/5.6 at 500mm and accept a larger/heavier lens, especially at the current price point.

So what is the 100-500’s maximum aperture opening at 400mm? That would depend on your camera settings in terms of aperture increments. If set at 1/2 stop increments, the aperture will be f/5.6 at 400mm. If set at 1/3 stop increments, it will be rounded to f/6.3. Ultimately, in terms of aperture, you will be sacrificing about two thirds of a stop of light for the additional 100mm.

<Stork-billed kingfisher (Pelargopsis capensis)>
EOS R6 + Mount Adapter EF-EOS R + EF 100-400mm f/4.5- 5.6L IS II USM
1/2000s, ISO 3200, f/5.6

<Oriental Pied Hornbill (Anthracoceros albirostris)>
EOS R6 + RF 100-500mm f/4.5-7.1L IS USM Lens
1/1250s, ISO 5000, f/7.1

In terms of bokeh and depth of field, as long as conditions are right and you position yourself well for decent background separation, you will be able to achieve subject isolation. With smaller apertures (f/7.1) like the one on the RF 100-500 at 500mm, you can expect to need a much larger background separation to achieve a smooth, uncluttered background as compared to a lens with a larger aperture at the same focal length.

Another exciting performance feature that both lenses possess and that Canon should be very proud of, is the minimum focusing distance of the lenses (100-500 at 90cm and 100-400 at 98cm). This allows all sorts of close-up photography and expands a great deal of compositional freedom, making the versatility of these lenses a tier up from any competitor telephoto zooms.

<Peregrine Falcon (Falco peregrinus)>
EOS R6 + RF 100-500mm f/4.5-7.1L IS USM Lens
1/200s, ISO 200, f/10

As expected of any telephoto L-lens from Canon, 3 modes of image stabilisation (IS) are available for use. Mode 1, correcting vibrations in all directions, more suited for static subjects. Mode 2, correcting vibrations for panning work and compensating for any movements perpendicular to panning direction which is perfect for moving subjects. Mode 3, correcting vibrations only during exposure/shutter release, sort of a hybrid of mode 1 and 2.

<Mangrove Pit Viper (Cryptelytrops purpureomaculatus)>
EOS R6 + RF 100-500mm f/4.5-7.1L IS USM Lens
1/80s, ISO 3200, f/7.1

This is where the 100-500 really shines. The 100-400 has a 4-stop rated internal image stabiliser system where by the 100-500 has an additional stop, offering 5 stops of built-in image stabilisation. It doesn’t stop there, the new R5/R6 are also the first Canon camera bodies to feature in-built image stabilisation (IBIS). This IBIS works together with the optical IS in Canon’s lenses to provide even more stabilisation. I shot the image of the Mangrove Pit Viper above handheld at 500mm at a shutter speed of 1/80s.

<Grey-headed Fish Eagle (Haliaeetus ichthyaetus)>
EOS R6 + Mount Adapter EF-EOS R + EF 100-400mm f/4.5- 5.6L IS II USM
1/2000s, ISO 5000, f/5.6

<Stork-billed kingfisher (Pelargopsis capensis)
EOS R6 + RF 100-500mm f/4.5-7.1L IS USM Lens
1/2500s, ISO 10000, f/7.1

IS works wonders for both lenses but the 100-500 has an added benefit due to the new RF mount for the R system. Having a larger image circle in the RF mount compared to the EF mount allows more room for sensor movement. Furthermore, the RF mount features a 12-pin two-way communication that allows the transfer of information and feedback that maximise IS performance for RF lenses. Having the 100-500 mounted on an R5/R6 will grant a total 6-stop benefit, making it the perfect handheld wildlife setup that is truly game-changing at lower shutter speeds in challenging light situations.

<Striated Heron (Butorides striata)>
EOS R6 + RF 100-500mm f/4.5-7.1L IS USM Lens
1/2000s, ISO 10000, f/7.1

It is guaranteed to get tact sharp images with either of these lenses. With more megapixels on a body like the R5 (45mp) compared to the R6 (20mp), you will be granted more cropping power and retained detail. 20mp does not give you much to work with especially on a full framed sensor. Having enough pixel density could be a high priority to some when shooting wildlife for the freedom to extract detail when needed. Thus, when using the R6, the extra 100mm reach would be more beneficial than using the EF 100-400mm ii.

<Stork-billed kingfisher (Pelargopsis capensis)
EOS R6 + Mount Adapter EF-EOS R + EF 100-400mm f/4.5- 5.6L IS II USM
1/2500s, ISO 10000, f/5.6

<Blue-tailed Bee-eater (Merops philippinus)>
EOS R6 + RF 100-500mm f/4.5-7.1L IS USM Lens
1/2000s, ISO 1600, f/7.1

Both lenses worked splendidly when it came to AF performance. There were no noticeable differences in terms of acquisition and accuracy. Furthermore, animal eye AF tracked just as well on both lenses. It is exciting to know that you may slap on any EF lenses and get an amazing performance even with an adaptor on. Canon has truly outdone themselves in this field.

<White-headed Munia (Lonchura maja)>
EOS R6 + Extender RF 1.4x + RF 100-500mm f/4.5-7.1L IS USM Lens @560mm
1/1250s, ISO 4000, f/8

My opinions on using extenders have always been mixed. They are expensive, degrade image quality ever so slightly and perform much better with super telephoto primes and on the more advanced camera bodies. For those unaware, here’s a short crash course on extenders on Canon systems.

The EF 1.4x iii and EF 2x iii have been in the market for a long time now (2010 release) and are similarly priced at around $500-600 SGD. Your focal length when using a 100mm lens would become 140mm and 200mm respectively. However, you will also lose 1 and 2 stops of light respectively (the largest aperture on an f/5.6 lens becomes f/8 or f/11). For those who aren’t using the latest camera bodies (especially on DSLRs), the AF system usually limits coverage on f/8 or smaller lenses. Thus, you may be looking at only single point AF or just a small zone/surround AF. Performance drops in terms of AF performance (acquisition and accuracy) and image quality (slightly) especially if you are not using top tier gear/lenses (e.g 1Dxii / 600mm f/4 etc).

<Blue-eared Kingfisher (Alcedo meninting)>
EOS 7Dii + EF 1.4x iii + EF 100-400mm f/4.5- 5.6L IS II USM
1/200s, ISO 400, f/8

Personally, I used the 1.4ex iii on my 7Dii & 80D together with the 100-400mm and there are reasons why I hardly used it despite the longer focal length at 896mm (400×1.6×1.4) at f/8. To get really tact sharp images, lighting conditions have to be good and you need to bump up your shutter speed to compensate for motion blur. Coupled with the light loss, expect ISO levels to increase unless you have a tripod. Without a camera that has good low light performance, noise levels would be through the roof. Note that some extenders work better than others, meaning that you need to get yourself a good copy. In certain body + lens combinations, AF micro adjustments have to be made to fix any front/back focusing.

<Crested Goshawk (Accipiter trivirgatus)>
EOS R6 + Extender RF 1.4x + RF 100-500mm f/4.5-7.1L IS USM Lens @700mm
1/250s, ISO 2000, f/10

Things get really interesting with the new RF 1.4x and 2x extenders priced at a whopping $829SGD and $999SGD respectively in retail. Light loss is also the same as the EF extenders. However, due to the design of the extenders and the RF 100-500, it is physically impossible to have the lens fully retracted which the extenders mounted. With the 1.4x the lens becomes 420-700mm and with the 2x, a 600-1000mm lens. Do note that it is impossible to stack these extenders.

In my testing of the RF 1.4x extender, I was simply blown away by the results. Shooting handheld was a breeze, images obtained were sharp and AF worked just as well, with no hassle of any AF micro adjustments. The IBIS and lens IS definitely played a part in getting those tact sharp details. If I were to own one myself, I can foresee myself using it very often. Wildlife photographers should be feeling really excited about the super telephoto primes that will eventually be manufactured for the R system, these extenders are the perfect compliment.

Unfortunately, I did not manage to test:
1) the 100-500 with the RF 2x extender + EOS R5/6
2) the 100-400 with the EF 1.4x iii + adaptor + EOS R5/6

Will update this article when I do.

<Stork-billed kingfisher (Pelargopsis capensis)>
EOS R6 + Mount Adapter EF-EOS R + EF 100-400mm f/4.5- 5.6L IS II USM
1/2000s, ISO 1600, f/5.6

So is it worth the upgrade? I believe it would boil down to whether you are in fact using the R5 or the R6. The two cameras are very similar in many aspects in terms of performance but the 45MP CMOS sensor of the R5 undoubtedly grants an edge that many wildlife photographers pursue: cropping power. The ability to extract every intricate detail on your subject is highly sought after and cropping power can be an “alternative” to having a longer focal length if resolution allows. 400mm or 500mm on a full frame sensor may be enough for some, but the vast majority would agree that shooting with least 600mm would be the most ideal for wildlife photography. The R6 only has a 20MP sensor, not much pixel density to work with despite the better low light performance. If you are using the R6, it would make more sense to upgrade for the longer focal length. That being said, if you are on the R5 and want a longer focal length and the other benefits mentioned above like the enhanced IS etc, then go for it.

The RF lens would unfortunately burn a big hole in your pocket (approx $4000 SGD) and that 7.1 aperture may be a turn off for some consumers. I would have expected Canon to come up with a telephoto zoom that could at least match Sony’s widely popular 200-600 f5.6-6.3 lens, but this premium L lens is definitely a large step into the wildlife market. I also do not fancy the design of the extenders that disallow the lens to be fully retracted and function as a 140mm – 700mm lens. That being said, high performance and image quality is guaranteed with the lens.

This could possibly be the most powerful handheld wildlife setup in the market now. Pairing amazing Canon glass with the new revolutionary R5/R6 bodies make it even easier to yield that shot you’ve been yearning for. I found myself getting so many sharp shots in focus and getting action shots have simply never been easier, and thats an understatement. The two lenses are pretty impressive in all regards but to future-proof your investment in Canon glass, I would personally invest in RF lenses.

Do contact me if you have any comments or questions!