At the time of writing, the Canon EF 100-400 L F4.5-5.6 is one of the most popular of Canon’s L-series zoom telephoto lenses.
It is also one of the older L-series lenses in Canon’s line-up, having been introduced around 1998. There have been persistent rumours that it will soon be replaced, but in it’s current form, it continues to sell very well. It maintains high sales volumes for a number of reasons, not least of which are its wide range of focal lengths and good imaging performance, combined with relatively light weight. The selling price also means that it costs less than most other Canon lenses that either have bigger maximum apertures or similar focal length, so it represents good value . In recent times, many of Canon’s newer lenses have shifted their prices upwards, when compared to models that they replace. This may be another reason why Canon have continued to make the EF 100-400L available for so long.
ABOUT THE LENS
The EF 100-400L is somewhat unusual in that it has a sliding zoom mechanism, or as Canon refer to it, linear extension type. The outer barrel extends forward and retracts, with no rotation. Both barrels are constructed entirely of metal, and the mechanism is a robust one, which is something that has been proven by some of the early examples of these lenses that are still in use many years later.
The lens mount is standard Canon EOS, but with no rubber weather-sealing ring. The lens barrel is smooth ahead of the mount, without any of the grip-assist ridging found on some other Canon white lenses.
There is a distance scale on top of the lens, and a panel with switches for AF/MF (to switch between autofocus and manual focus) as well as a distance limit switch.
The EF 100-400L f4.5-5.6 IS is supplied with the tripod ring as standard which is a good value-add.
For some reason, Canon do not supply some of their other similarly priced lenses like the EF 70-300L or the EF 70-200L f4 IS with their respective tripod rings, they have to be bought as costly accessories. The EF 100-400L comes in its box fitted with Tripod Mount Ring B. The ring has a black line that marks its vertical alignment with the lens, and a knurled locking knob. Unscrewing the locking knob, which is captive, allows the mount to be rotated and removed from the lens.
The mount does not open completely and has to be slid backwards from its mounting grooves, and can only be removed entirely when there is no camera body mounted on the lens.
Ahead of the tripod mount is a switch panel that is home to the image stabilizer controls. These switches protrude slightly from the panels that they are housed in, and can be quite easily shifted accidentally whilst handling the lens. The IS system is one of Canon’s earliest, and is good for two stops of stabilization.
At the back end of the outer barrel, there is a rotating locking ring, which sets the tension on the sliding barrel. The focus ring itself is quite narrow, made of rubber, with a fine texture to its ribbing, and easy to differentiate from the zoom control by feel alone.
The front lens element and filter thread are 77mm in diameter. The lens is supplied with two end caps, one for the lens mount and the other a 77mm squeeze-on type.
A black plastic lens hood, ET-83C, is supplied with the lens. It is of the type that screws into place. There is enough room inside the lens hood to easily attach or remove the lens cap. When these lens hoods are new, the attachment is firm and positive, but after lots of use the mounting wears and loses tension, and the fit can become rattly and loose. This is an area that Canon have improved upon in newer lenses. I make every effort to minimize how many times I mount and remove lens hoods, on all my lenses, to minimize this wear and tear. The inside of this lens hood is covered in non-reflective flocking, which helps prevent any stray light rays from being reflected onto the front lens element. The ET-83C can be reversed and stored on the lens.
With the sliding barrel design, the zoom ring on the EF 100-400L does not rotate and is textured to assist grip when pushing or pulling the barrel to change focal length.
The EF 100-400L changes it size considerably when zooming in or out, as can be expected from a 4 x zoom, with a compact, retracted form factor. The lens is not weather-sealed. I have seen complaints on the internet about the lens being susceptible to ingesting lots of dust. In my experience I can say that I have not really noticed more dust ending up on my camera sensor when I use the EF 100-400L. When I worked as a guide in Botswana, more than ten of my colleagues owned this lens, using them on a daily basis in hot and dusty conditions, and if they were taking in more dust, it was not something that clearly affected the lenses usefulness or function during that time. Obviously, the EF 100-400L displaces a large amount of air when the outer barrel is moved from one end to the other of it’s range, and for that reason, there are other lenses which are better at staying free of dust. The same goes for moisture, in that lenses that displace less air are typically better at staying clean. At the same time there are EF 100-400L lenses doing their jobs on a daily basis in marine environments where moist air is a concern. I have seen a few EF 100-400L lenses eventually show some scuffing of the paint on the inner barrel after heavy and rough use, although the lenses all still functioned well. The EF 100-400L feels well-built, and up to the rigours of wildlife or photojournalism use.
When this lens was designed, Canon had not yet developed some of the special optics coatings that are applied to their newer L-series lenses.
The EF 100-400L has an optic design made up of 17 elements, arranged in 14 groups, with a rear-focus system. The design includes one flourite lens element (which is positioned just behind the front optic), and one UD (Ultra Low Dispersion) element amongst the optical components. The flourite element improves image quality and weighs less than other optics. Flourite and UD elements are highly effective at combating chromatic aberrations amongst other things. Both of these materials are more costly than regular optic materials.
The lens comes with a zippered, padded nylon bag that can hold the lens with its hood reversed.
HOW WELL DOES IT WORK?
The EF 100-400L IS is not very heavy for what it does, weighing in 1360g. How heavy it may seem to you will depend on what other lenses you use. It is significantly lighter than any Canon 70-200 f2.8 lens. For most people it is light enough that it can be handheld quite comfortably. With the long outer barrel extending quite far at full zoom, the balance of the lens’ weight shifts. Fully extended at 400mm, the EF 100-400L IS can feel very light toward the front end. This is not typical of most telephoto lenses weight distribution, with heavy front ends being the norm. Light is good with lenses, and getting accustomed to the balance of the EF 100-400L IS doesn’t take long. If you are someone who has been shooting with 70-300mm consumer lenses, then the EF 100-400L will feel heavy enough.
Overall though, it is compact enough that it can be mounted on a camera and worn on the strop, hanging from neck or shoulder, at least for a while, in its retracted form. It balances well on medium-sized bodies like the Canon 5Dmk3 and the 7D but works very well on the Rebel/T5i -sized body too, and feels quite light mounted on a 1D series body.
The zoom ring is situated quite far forward on the outer barrel, and has tranverse ridges for grip. Zooming in is accomplished by simply sliding the outer barrel forward and zooming out by pulling it back toward the camera. The action of the sliding zoom is very smooth on the EF 100-400L, and there is no play to be felt, even with lenses that have seen some use. The rotating collar at the base of the outer barrel makes it possible to set the tension on the zoom. I like to turn the ring until there is just enough resistance to prevent the outer barrel from sliding down even if I point the lens toward the ground. I find it quite comfortable to use the linear zoom on the EF 100-400L IS, as my left hand only has to move backward or forward to reframe my subject, and I find that I can easily do that whilst shooting even if the subject is coming directly towards me. In some ways it can be easier than trying to twist my left wrist around whilst handholding which I may have to do with a rotating zoom. On the negative side, sometimes I find it a bit fiddly trying to get the tension set just right on the zoom, and end up with it too loose and shifting too easily, or too tight. Whilst the zoom can be slid back and forth easily with one hand, I usually need to use two hands to adjust tension on the locking collar, just because it tends to turn with the focus ring unless I hold each one separately. This can waste time in the field.
I take care to keep the lens fully retracted whenever I am not shooting it fully extended, which means tightening up the tensioning ring firmly, to prevent the barrel sliding from sliding forward with force accidentally. At full extension, the lens is quite long, and carrying it on a neck strap like that may put additional stress on the camera bayonet mount.
I have tried to describe as fully as possible, what using the linear zoom mechanism lens is like, in real-world use, because it is an aspect of the lens that makes it quite different to most other zooms. I am quite comfortable using the sliding zoom but there are other photographers who are not able to get comfortable with it, and prefer to avoid the lens because of that.
Overall, the compact size resulting from the linear zoom design and the light weight mean that the EF 100-400L is an ideal lens for handheld use whilst walking around and photographing in places like botanical gardens, and nature parks. Those same attributes make it a good choice for travelling, when space and weight are critical considerations. With a minimum focus distance of 1.8m, the EF 100-400L provides enough magnification at a near enough distance, that it is possible to capture quite small subjects, like butterflies, dragonflies and other larger insects.
I mount an alloy lens plate made by Really Right Stuff onto the lens collar. This allows me to mount it very quickly on my tripod, and makes for a larger handle for carrying the lens. The extra size of the plate also makes an ideal place to rest the bottom of the lens on, when I am leaning it on something for support.
Using the lens on a tripod, with a tripod mount and the accessory lens foot gives a fairly balanced feel to the setup, though the point of balance will change when zooming in or out as the lens length changes. Extended, the EF 100-400L is too long to be used with the camera itself mounted on the tripod. It is far better to connect the tripod to the lens mount itself.
The EF 100-400L IS has such a wide range of available focal lengths that it is very well suited to wildlife photography. On the long end, 400mm of focal length is enough for some close-up portraits even of larger animals, or those that allow a close approach. The maximum focal length is even just enough for some serious bird photography, though one will need to be quite close to the birds, or to stick to larger species. The shorter end of the focal length range, which is 100mm, is useful for capturing scenes of animals in their environments.
With the image beneath this text I framed the desert-adapted elephant at 130mm, to include the rocky cliff and sand dunes for scale.
Then, without changing my own location or position, I zoomed in to 400mm and framed a scene with the elephant taking up almost a quarter of the scene.
Because of its wide focal length range, the EF 100-400L also serves well as a landscape lens that can frame multiple scenes from one place, and compress distant features of a landscape to good effect. It is also light enough that it can be carried along in a hiking bag on long walks to get to those special views.
Overall, the EF 100-400L works well in a variety of roles, including use for wildlife, sport, airshows, landscape and travel photography, with some to-be-expected trade-offs.
Due to its age, the EF 100-400L f4.5-5.6 IS has one of Canon’s early image stabilization systems. It is rated to be effective to two stops of shutter speed. What this means to the user is that using IS will significantly improve the chances of taking sharper images at lower shutter speeds, than with a lens that is not equipped with IS. In use, this older IS system can be heard working, but is not overly loud. The system has two IS Modes. Mode 1 is best for general handholding, whilst Mode 2 is best suited to panning, which would include tripod use. If you are going to be shooting from a tripod at very slow shutter speeds, for instance in very low light, then it is definitely best to turn IS off. Newer Canon IS systems are effective beyond 4 stops of shutter speed, and have tripod sensing capability. Whilst the IS system in the EF 100-400L f4.5 IS is not quite so sophisticated, it is nonetheless effective, and a valuable feature in this lens’ specifications.
The EF 100-400L is a lens that has somewhat variable autofocus performance, depending to some degree on what camera body it is mounted. When paired with a Canon 700D/Rebel type body, focus drive can be quite slow. This is to be expected, in a lens with a wide range of focal lengths. Shooting with the lens on a 5Dmk3, or a 1D body, delivers much snappier autofocus response. It is possible to speed up focus drive regardless of which camera body is being used, by means of the distance limiting switch on the side of the lens. There are two settings, 1.8m to infinity and 6.5m to infinity. If you shoot with the setting on 1.8m, then the lens will be able to focus on subjects as close as 1.8m. However, this also means that the lens has a much wider range to work through when focusing on something distant, which can result in slow AF response. If you are in a situation where you are certain that you won’t have need to focus closer than 6.5m, switching to the longer minimum focus distance setting results in much faster AF drive and performance. I try to always remember which distance setting I am using, in order to maximize how well the lens focuses.
Initial pick-up of a subject is surprisingly fast, on all bodies, especially when the subject contrast is high. At it’s maximum focal length, the EF 100-400L f4.5-5.6 IS has quite a narrow field of view, and like any telephoto lens, good long lens technique will enable the autofocus to work at its best. Keeping as still as possible becomes very important. I also make sure to limit how far the EF 100-400L has to search for focus too, by trying to focus on or near my expected subject distance, even when I don’t have a clear view. This can be invaluable when shooting moving subjects. In other words, if I am waiting for an approaching bird to fly towards me, and I can see it way off in the distance, I will pre-focus the lens at a good distance where I may want to start tracking, before my subject gets there. This can be accomplished by aiming and focusing on something big and high in contrast at a suitable distance, or by manually turning the focus ring until the lens is focused at the right distance. Pre-focusing in such a manner soon becomes second nature, and it prevents time-wasting searching when the lens has to rack back and forth hunting for contrast or subject.
Skilled photographers take fantastic images of all variety of moving subjects with the EF 100-400L every day. Given it’s wide range of focal lengths, it’s moderate maximum aperture of f5.6, and age of design, it does a good job at autofocus. At the same time, many of Canon’s newer zoom lenses will focus faster and more accurately. These would include all of the EF 70-200L models, the EF 70-300L f4-5.6 IS, the EF 200-400L f4 1.4x ext IS. The difference in performance between these lenses and the EF 100-400L is less in bright light but becomes more pronounced when light is low. Fixed focal length lenses, like the EF 400L f5.6 that cost a similar amount also focus faster and more accurately.
Bear in mind that my expectations of autofocus are based on photographing wildlife in natural light, and with moving subjects something that I try to concentrate on, and my discussion of the autofocus performance of the EF 100-400L is based on using it for that role. For still or slow-moving subjects, autofocus works quickly and accurately.
Camera bodies used
Over time I have used the EF 100-400L on the following Canon EOS bodies: 350D, 30D, 40D, 50D, 60D, 7D, 6D, 5Dmk2, 5Dmk3, 1Dmk4 and 1DX.
On the Canon 70D/7D with its APS-C sized sensor, the field of view is roughly equivalent to 160mm-640mm. This pairing makes for a compact combination with lots of resolution, reasonable autofocus, and at its best in bright light.
On the now discontinued Canon 1Dmk4, which has an APS-H sized sensor, the field of view is roughly equivalent to 130mm-520mm. Autofocus is good, and this combination works well in a variety of conditions.
On the Canon 5Dmk3 and 1DX, full-frame sensors utilize the entire image circle projected by the EF 100-400L. The wide end of the focal length range, 100mm becomes noticeably wider and more useful for capturing surroundings and environments on these bodies than with other smaller-sensor Canon dslrs. Both these camera bodies got the best out of the EF 100-400L, with their great high-iso performance balancing out the need for high iso settings to make up for the lenses ‘slow’ maximum aperture of f5.6. Their autofocus systems also drove the EF 100-400L more positively than any other Canon dslr bodies. I also got decent results with the Canon 6D and this lens, although I used only the centre AF point for moving subjects.
The EF 100-400L f4.5-5.6 IS will work with a Canon 1.4x extender attached to it. This combination effectively creates a 140mm-560mm f8 maximum aperture lens. Autofocus will only be possible in this configuration if you are using a 1D-series body, or a 5Dmk3, to the best of my knowledge, and not all AF points may be available. Such a combination will be best utilized in bright light, and won’t be ideal for fast-moving subjects. The viewfinder of the camera will also darken quite a lot. I have not used the lens with any extenders in the field.
It is also possible to mount a Canon EF 2.0 x extender to the EF 100-400L, but as far as I am aware, normal, through the viewfinder, autofocus will not work. On the other hand, it may be possible to focus using Live View, with the 70D and it’s Dual Pixel Live View focus rated to function at a maximum aperture of f11. Although I have spent time shooting with the 70D, I did not fit a 2x extender to the EF 100-400L and try this out for myself.
I always shoot in RAW and process my images in Adobe Camera Raw, which is very similar to Adobe Lightroom and its Develop Module, and then finish them off in Adobe Photoshop. My evaluation of the lens performance with regard to image quality is based upon my normal workflow.
The only time I ever mount any kind of filter like a UV Haze or protective clear filter to the front of this lens is when I may be using it in extremely poor conditions, like ocean-salt spray or airborne dirt as found at motocross events. The optical performance can be easily degraded by filters. The deep lens hood does an excellent job of keeping the front element safe most of the time.
The EF 100-400L is a zoom lens which delivers acceptable image quality at wide-open aperture settings. Stopping it down, beyond 5.6 (at longer focal lengths), to apertures in the f6.3 – f8.0 range brings about noticeable improvements to sharpness.
I choose my aperture settings for creative reasons, depth of field and background blur being part of that, but still taking into account my shutter speed, and not allowing it to drop too low. I shoot handheld most of the time. I choose to shoot the EF 100-400L at its’ wide open aperture of f5.6 much of the time, because I am purposefully trying to blur the background, or because the low light I may be working in demands the biggest available aperture setting to give me more shutter speed. When used in this way, the EF 100-400L gives up a little image quality, in sharpness, and contrast, when compared to the other Canon L-series lenses like the EF 70-300L, all three of the EF 70-200L lenses and the EF 400L f5.6. It is important to remember though, that I am comparing the EF 100-400L with a collection of L-series lenses, all of which either do less when it comes to maximum focal length, have shorter working ranges, or cost a whole lot more. Compare the EF 100-400L to most non-L series Canon lenses, and it will surpass them when it comes to image quality.
The image of the black-backed jackal above serves as a real-world example of the level of detail the lens can deliver, in good light and stopped down to f7.1. That image was cropped from a 10 megapixel original, to just 1.3mp, to represent an approximately 100 percent view, to illustrate fine detail. I stopped down here to make sure I had enough depth of field to get both eyes and nose in focus and I had enough light to accomplish that.
The Cape sparrow image above is another example of the kind of detail I get from the lens. This image was taken in good photographic light, and cropped from 22 megapixels to just 1.3megapixels, to illustrate what a 100 percent view looks like. I stopped down one stop for this shot, to f6.3. Images from the EF 100-400L have faithful colours. Contrast is also good, more so in brighter light.
More real-world images, this elephant above, shot at 400mm focal length, for a close-up shot in good light, and with the aperture wide open at f5.6. Taken in good light, this elephant image is nicely detailed. The image is cropped from 10 megapixels to just 1.4 megapixels to show a 100 percent view.
Close inspection of the elephant image above, taken after the sun had set, will reveal noticeably less detail than other sample images which were taken bright ambient light.
It is quite normal for zoom lenses to show some evidence of vignetting, or darkening of the edges of the frame. I photographed four images of the blue sky, two at 100mm, and two more at 400mm, at different aperture settings,with the lens mounted on a Canon 5Dmk3 full frame dslr to illustrate the vignetting.
100mm Focal length
At 100mm, and aperture wide-open at f4.5, vignetting is quite pronounced in the corners, gradually fading toward the centre of the frame.
Staying at 100mm and stopping down to f6.3 clears away most of the vignetting, with only slight shading left in the very edges of the frame.
400mm Focal length
Zoomed all the way to 400mm, and wide open at f5.6, the 100-400L again shows quite pronounced vignetting, particularly in the corners, gradually fading toward the centre.
Still at 400mm, stopping down to f7.1 clears the vignetting quite significantly, with some shading remaining deep in the image corners.
When shot at wide-open aperture settings, the EF 100-400L f4.5-5.6 IS shows the most vignetting of any of the Canon L-series zoom lenses that I routinely shoot with. I don’t consider this to be a major problem as it is very simple to get rid of such vignetting using Adobe Lightroom, Camera Raw and Photoshop, and Canon’s own Digital Photo Professional, that comes bundled with all Canon dslr’s. If you shoot jpg images, then most modern Canon dslr bodies will have the option of taking care of the vignette in-camera, using the Peripheral Illumination Correction feature.
Slight vignetting can also help to draw attention to my subjects, which are typically not near the darker edges of the frame.
Corner shading or vignetting is much less noticeable when the EF 100-400L is used on cameras with smaller sensors like the EOS 700D, 70D or 7D as these cameras utilize only the central part of the image circle.
With 400mm of focal length, the EF 100-400L can effectively blur out backgrounds when photographing wildlife, especially if the focused subject is close to the camera.
The cheetah above was photographed with the EF 100-400L at 400mm of focal length, and the aperture wide-open at f5.6. In my own shooting, I often choose to shoot with open apertures, to help blur backgrounds for creative purposes, and I typically end up shooting any telephoto lenses with a f5.6 maximum aperture, at that wide-open aperture much of the time.
The lion portrait above, composed at 350mm, was taken with the aperture stopped down to f7.1, in order to get more detail from the subject, at the expense of a more structured background, with less blur.
In order to further evaluate the quality of the bokeh and background blur that the EF 100-400L f4.5-5.6 IS produces, I shot it side by side with the lens that might be its closest Canon competitor, the EF 70-300L f4-5.6 IS.
I didn’t find a whole lot of difference between the two lenses when it came to the structure of the bokeh at 100mm focal length, though I don’t typically spend too much time looking at background highlights zoomed in to 100 percent when I am processing my images. The EF 70-300L aperture circles may have smoother edges to them. If there are bigger differences they are not relevant to my own imaging needs.
To me, there is not a whole lot of difference in the structure of the background blur from these two lenses when shot at similar settings. I tried to get the two images as close to one another in terms of subject size, which meant a focal length of 285mm on the EF 100-400L and 300mm on the EF 70-300L. The difference in focal length readings from Adobe Lightroom (285 compared to 300) may be ascribed to the close focus distance of the test subject when I took the images.
I have not picked up enough evidence of chromatic aberration, in my images taken with the EF 100-400L to warrant their removal using Lightroom or Photoshop.
Flare happens when stray light gets reflected off surfaces inside the lens and either shows up in the image as small, circular bright patches or even sometimes as large areas of low contrast. The EF 100-400L doesn’t appear to be particularly susceptible to excessive flare effects, although like many other older Canon tele zoom lenses, it can struggle to focus on a backlit subject when there is a strong light source in the frame. At such times I usually try to find focus using a single AF point, and on the edge of my subject.
Some internet posts I have read have recommended to potential buyers of a Canon mid-range telephoto zoom lens to choose the EF 70-300L over the EF100-400L and then deal with the lack of extra focal length in the 300mm zoom lens by cropping it’s images to match a 400mm perspective. I carried out this exercise and posted the images here for comparison.
I shot with the same camera body, from the same tripod mount position, with both lenses at their maximum focal length, which was 300mm and 400mm respectively. Those images are directly below.
EF 70-300L at 300mm
EF 100-400L at 400mm
It can be seen that 400mm gets you a lot closer to your subject, and also blurs the background more powerfully. Whilst it is possible to crop the image taken with the shorter focal length lens ‘tighter’ you cannot make up for the more diffuse background that the EF 100-400L creates at this distance.
I then cropped the image from the EF 70-300L at 300mm focal length until it closely matched the size of the subject, in the image taken with the EF 100-400L.
Cropping an image taken with the EF 70-300L at 300mm, on my Canon 5Dmk3, until the subject matched the subject size from the EF 100-400L at the same distance, left me with around 14 megapixels from an original file of 22 megapixels. At pixel level, the image from the 70-300 enjoys a slight sharpness and contrast advantage, which may be negated somewhat by the loss of resolution resulting from the crop. The image taken with the EF 100-400L shows superior background blur. It may not be clear from this comparison which lens is superior, although I would suggest that if you are going to be shooting at 400mm most of the time, then the 100-400L holds the advantage. The EF 70-300L certainly has good enough image quality to withstand such a crop, but the background blur of the longer lens cannot be easily replicated. If you don’t need to blur backgrounds in your own shooting needs, like birds in the sky, then it becomes less of a factor.
Something that I learned from fellow guide and exceptional photographer Andy Biggs is that the EF 100-400L can be stopped down quite far, and on a 1Dmk4, it will close down to as small an aperture as f40. Such a small aperture setting allows for slow shutter speeds even in bright light, making the EF 100-400L an ideal lens for motion blur photography when slow shutter speeds are needed.
To sum up the image quality of the EF 100-400L, I find that I need to spend a little more time working on contrast, vignetting and sharpening to get the best results from raw images taken with this lens.
The EF 100-400L can and does take images that are good enough to be published in magazines, to win photo contests, and make fantastic fine art prints.
When it comes to options, Canon offer several lenses that come close to the EF 100-400L f4.5-5.6 IS.
One option is the EF 70-300L f4-5.6 IS. This lens is lighter, shorter, offers slightly better image quality, faster autofocus, 30mm wider focal length, four- stop image stabilization and weather-sealing. The EF 100-400L has an extra 100mm of focal length which can be significant for far-off subjects and can generate more background blur, and is competitively priced.
Another option is the EF 70-200L f2.8 IS ii, matched with an EF 2x Extender iii, to create a 140mm-400mm f5.6 zoom combination. The 70-200 and 2x extender offers fairly similar performance to the EF 100-400L in optical performance, as well as autofocus drive. On the plus side, this combination enjoys weather-sealing superiority, a constant physical size when zooming in or out, and Canon’s newest Image Stabilization system, good for up to 4 stops. You also have the advantage of being able to remove the extender when subjects are nearby, and enjoy all the advantages of the f2.8 lens maximum aperture zoom. Disadvantages of the EF 70-200L f2.8 IS ii and 2x Extender iii are size, (it doesn’t retract), weight, and cost. In an earlier post I compared the EF 100-400L f4.5-5.6 IS and EF 70-200L f2.8 IS ii plus 2x extender iii in some detail.
Yet another option in the Canon lens stable is the EF 28-300L f3.5-5.6, which has a much wider 28mm maximum focal length range, bigger wide-open aperture and three stop image stabilization. In comparison, the EF 100-400L is significantly lighter, 100m longer on the far end, and costs a lot less. I have yet to use the EF 28-300L in the field, and cannot at the time of writing offer a real opinion on it.
Wide range of focal lengths
Relatively light weight for focal length range
Compact size retracted
Value for money
Lack of weather-sealing
Raw images require extra processing
The EF 100-400L f4.5-5.6 IS is a good overall performer, and one that has for a long time been a favourite amongst many Canon photographers looking for a one-lens solution to multiple photographic applications . It is likely that a new version of this lens from Canon would be able to improve both its low-light image quality and light light autofocus, but right now, the EF 100-400L f4.5-5.6 IS gets the job done. No other single Canon lens L-series lens is nearly as versatile, in the same price, weight or size category and this makes the EF 100-400L f4.5-5.6 IS a very useful piece of equipment to own.