In the early days of Canon’s RF mount lens rollout we saw several high end models but not much from the budget end of the spectrum.
In recent times Canon has been busy rectifying the imbalance with some very attractive, moderately priced optics for enthusiast non-professional users.
Depending on where you set the bar for “moderately priced” these include the RF 16mm f2.8, 35mm f1.8, 50mm f1.8 , 85mm f2, RF 15-30mm, 24-50mm, 24-105mm STM, RF-S 18-45mm, 18-150mm, 55-210mm and the subject of this review, the full frame RF 100-400mm f5.6-8 IS USM.
In Canon-world, if you pay more, you get more of everything. Conversely if you pay less you get less of everything. This usually means less zoom range, smaller maximum aperture, fewer features, no hood supplied, fewer levers and dials on the lens, smaller size, less mass, slightly slower AF using less expensive technology and more plastic in the construction. It also usually means a slightly lower level of optical performance for resolution, contrast, distortion, flare and aberrations.
But “slightly lower” still means these lenses are capable of excellent results if used thoughtfully.
When we compare the RF 100-400mm with the much more expensive RF 100-500mm L we find that the 100-400mm is one third the price, smaller, lighter and offers a smaller maximum aperture. In practice the difference between the two lenses with regard to size, mass and ease of handling is much greater than comparison of specifications or product photos might lead us to believe.
Specifications summary
Min length with filter and cap | Max length with filter and cap | Mass grams | Barrel diameter mm | New price AUD* | Hood in box | Tripod foot in box | Material | Elements groups | |
RF 100-400mm f5.6-8 | 176mm | 252mm | 635 | 80 | 1379 | N | N | Plastic | 12/9 |
RF 100-500mm F4.5-7.1 L | 218mm | 309mm | 1365 | 94 | 4699 | Y | Y | Magnesium | 20/14 |
EF 70-300mm f4-5.6 IS 2 USM | 176mm with adaptr for RF | 710 | 80 | 999 | N | N | Plastic | 17/12 |
The 2016 EF 70-300mm f4-5.6 IS Mk2 USM lens is still available new and I have used it on my RF mount mirrorless cameras with the adapter. This is a very nice lens delivering a high level of imaging capability at a modest price.
The RF 100-400mm is, I guess we could say, the spiritual successor to the 70-300mm. In the transition to the RF mount Canon has been able to keep the length (including adapter) the same, reduce the mass and increase the reach. This has been possible because RF mount mirrorless cameras can autofocus at small apertures right down to f22 whereas most EF mount cameras would not AF reliably at an aperture smaller than f5.6. The reduced aperture has enabled an optical design with fewer elements while retaining a high level of imaging capability.
The 100-400mm is light enough to hold single handed when mounted on either a full frame or a crop sensor body.
As to specifications the 100-400 is a step up from budget level. Construction appears to be mostly plastic although the unit appears to be very well made. It has three rings on the barrel, for zoom, focus and adjustment to settings. There is a zoom lock slider, an AF/MF switch and a stabiliser ON/OFF switch on the barrel. AF is driven by Canon’s ultrasonic technology. The zoom action is very smooth with just the right amount of drag and no appreciable free play.
It is not rated as weather sealed.
With regard to optical qualities, my tests show that the less expensive lens is very close to the L lens in a large central area of the frame at all focal lengths but falls away slightly towards the periphery of the frame.
On my tests the 100-400mm is commendably resistant to flare and presents very little distortion or color fringing with RAW files processed in Adobe Photoshop. Autofocus is pleasingly fast and accurate on still or moving subjects.
On the R5 the 100-400mm works very well providing a useful focal length range for many types of outdoor activity when we cannot get close to the subject.
The 100-400mm is compatible with both the RF 1.4x and 2x extenders without having to zoom out before mounting the extender. However on the R5 with its high pixel count my tests showed no advantage to doing so compared to simply cropping. The extender might be more effective on a body with lower pixel density but I have not tested this.
Of particular note is the suitability of the 100-400mm for use on crop sensor bodies. It works very well on the R7 and R10 giving an effective focal length of 160-640mm, a very useful range for birds and wildlife or sports. On the R10 body the RF 100-400mm makes for a very handy, compact, light, high quality kit suitable for many kinds of outdoor use cases. All Canon’s advanced subject finding and tracking functions work very well.
I ran a series of tests comparing the RF 100-400mm on the R10 (max effective focal length 640mm) with the RF 100-500mm L plus RF 1.4x extender on the R5 (max effective focal length 700mm).
The R5 full frame combination costs four times as much as the R10 crop sensor one. I found that the more expensive kit does deliver a little more resolution but in sunlight or bright overcast the difference between the two kits is only visible on pixel peeping at 100% on screen. In lower light levels the kit using the larger sensor would score a more convincing advantage.
I use the 100-400mm lens near salt water quite often so I leave a 67mm Hoya HD mk2 UV filter mounted permanently with no detriment to image quality which I have been able to detect. The filter keeps salt spray, sand and other nasty abrasive junk off the front element of the lens.
Summary
The 100-400mm is one of a group of recently released RF mount lenses which deliver a very high ratio of performance to price.
As such it is a very easy lens to recommend for either full frame or crop sensor RF mount cameras.