Canon 400mm f/4 IS DO IS II Review: Battle of the light lenses
Introduction and technology:
Back in 2001 when Canon introduced the original EF 400mm f/4 DO IS, it was the first photographic lens with a multi-layer diffractive optical element. This element replaced the conventional convex refractive front element, hence the “DO” designation. A diffractive element features gratings that cause interference in the wave front of the incident light, bending the light in the desired angle. In principal, the effect of a conventional lens can be achieved with a much thinner and lighter diffractive element. In Canon’s original multi-layer design, the diffractive (DO) element is used not only to replace the front element, but also to “reverse” the chromatic aberration characteristics (CA) of a conventional lens. The end result is that the CA can be cancelled by combining just two elements, the DO element and a conventional element. This is shown in the figure below.
Since the DO element can bend the light to a greater degree, the elements can be placed closer to each other resulting in a shorter lens. However, there is no free lunch, since fabrication, bonding, and alignment of the DO elements are difficult, time consuming and expensive processes.
The original EF 400mm f/4 DO was a great experiment, it delivered on the promise of a light and compact lens. The bare lens was sharp if it lacked in contrast a bit.
While I liked the old DO lens when used bare, it had a major Achilles heel: very poor performance with both EF extender 1.4X and 2X. With the EF extender 1.4X, the RAW files were decidedly soft and the AF was slow and inaccurate. I would go so far as to say the lens wasn’t even usable with the 2X at all. At the same time, it’s fair to say Canon did not design the optical formula with extender usage in mind. As a result, the original EF 400mm F/4 DO was just a stabilized 400mm at the end of the day. At a price point exceeding $5000 during most of its production span, this lens was not a good proposition for bird or wildlife photographers coming out behind the EF 300mm f/2.8 IS (both series I and series II), which deliver sharp files even with a 2X extender.
However, Canon claim to have totally re-engineered this lens with significantly improved optical formula, better materials and improved manufacturing and calibration processes. Especially, the performance with the extenders has significantly improved, Canon claims. The MTF charts published on Canon’s website are so stellar that they are almost unbelievable.
Chuck Westfall, Canon USA’s technical adviser, kindly provided me with some details regarding the new lens’s design. The new EF 400mm f/4 DO IS II features a gapless multi-layer diffractive element. The air gap between the DO elements in the old lens causes refraction of light at the non-homogeneous interface between the gratings and the air, this in turn causes flare and loss of contrast in some shooting conditions. The gapless DO element preserves contrast and reduces flare. The difference between the two designs is shown in the figure below
It is easy to see that Canon have completely changed the optical formula for this lens compared to its predecessor. Unlike the old lens, the DO element is no longer the front element, but the the third element directly behind the UD element, as shown in the figure below. The UD element helps to reduce secondary spectrum aberrations. The new lens features Canon’s latest SWC (subwavelength structure coating) on one of its internal elements to reduce flare even further. Canon have also incorporated a large diameter ground and polished aspherical element. It contributes significantly to the improvement of the overall image quality in the new lens. In fact, this is the first time that Canon have ever used an aspherical element in a supertelephoto lens. In addition to redesigning the optics, Canon have also fitted the new lens with latest in AF hardware and software bringing it in line with the other IS II series supertelephoto lenses.
The new EF 400mm f/4 DO IS II has a high bar to pass. Not only does it have to match the stellar performance of the EF 300mm f/2.8 IS II, but it has to exceed it. The EF 300mm f/2.8 IS II is the current benchmark for short and compact professional telephoto lenses. It has been my favorite light travel lens for a while, delivering tack sharp files at wide open aperture and rapid AF. When attached to the EOS-1D X, the performance of this lens remains stellar in terms of both AF and sharpness even when used with the extender 2X III.
In this review we will find out if the new EF 400mm f/4 DO IS II is able to match this performance, in particular with extenders while shooting birds in flight.
400 vs. 300
First, let’s take a look at the specification of the new EF 400mm f/4 DO IS II compared to the EF 300mm f/2.8 IS II. These two lenses are very close in terms of their physical aperture (100mm for 400mm DO IS II and 107mm for EF 300mm f/2.8 IS II), as a result they are almost identical in diameter. They share the same lens hood as well. However, despite having a longer focal length, the EF 400mm DO IS II is actually a bit shorter than the EF 300mm f/2.8 IS II thanks to the incorporation of the DO element. The middle section of the EF 400mm f/4 DO IS II is also slightly narrower than the EF 300mm f/2.8 IS II. The photos below show both lenses side-by-side.
In terms of hand holding, both lenses are very easy to hand hold, however the EF 400mm f/4 DO IS II feels surprisingly more comfortable to hand hold for very long durations. This is because the center of mass is closer to the camera body, especially when the Extender 2X III is attached.
The table below compares the main spec’s between these two lenses. It is fair to compare these lenses at the same focal length for bird photography, especially when hand holding. For each focal length range, I have added the weight and the length of the extender needed to achieve the respective focal length to the bare lens.
As you see, for comparable effective focal lengths, the EF 400mm f/4 DO IS II is both shorter and lighter than the EF 300mm f/2.8 IS II. So at least on paper, the DO lens wins this category. The EF 300mm f/2.8 IS II has an edge in low light given its max. aperture of f/2.8 but at a short focal length of 300mm. This could be handy for some situations such as shooting bald eagles at close range but it could be a bit too short to be useful for other subjects. The EF 400mm f/4 DO IS II on the other hand, can provide up to 800mm of stabilized reach in a very compact package shorter than 12″ and lighter than 5.5 lbs. If the image quality (sharpness) and AF remain stellar at this setting, it is indeed a breakthrough for Canon users. Of course at $6899 the EF 400mm F/4 DO II is not a cheap date. We will now put it into an extensive test to see if it can command such a price.
For comparison, I used my Dollar bill to split any differences between the two lenses when shooting under controlled conditions. I used a tripod, speedlite 580 EX II and a remote release to eliminate any vibration for this test.
I moved my tripod closer to the bill with the EF 300mm f/2.8 IS II in order to (approximately) equalize the subject size in the frame and concentrate just on absolute sharpness. Obviously, when shooting from the same distance, subject will be larger with the EF 400mm DO IS II. I used the widest aperture available for each combination of the lens plus extender. This is how I use my lenses in the field for avian subjects.
Lens+ Extender 1.4X III:
Lens+ Extender 2X III:
As you see, there is no visual difference in contrast or sharpness between the outputs from these two lenses attached to the EOS-1D X with or without an extender. I did not use any chromatic aberration or other lens correction during RAW conversion, it is straight out of the camera. I think it is safe to say that the simulated MTF charts on Canon website are pretty accurate. The EF 400mm f/4 DO IS II is razor sharp even with the Extender 2X III at its widest aperture setting (f/8), it is in a whole different league compared to its predecessor.
In order to demonstrate the difference in maximum achievable focal length between the two lenses I shot the Dollar bill from the same distance with the extender 2X III attached, this will give a focal length of 600mm with the EF 300mm f/2.8 IS II and 800mm with the EF 400mm f/4 DO IS II.
At 800mm the subject is about 78% larger in the frame compared to 600mm. This is a significant difference in terms of reach. Of course, this combination is a full stop slower than the EF 300mm f/2.8 IS II + Extender 2X III which could put it at a disadvantage in very low light situations. However, when needed, you can still get 560mm at f/5.6 by attaching the extender 1.4X III to the EF 400mm f/4 DO IS II. Furthermore, thanks to the EOS-1D X, I can crank up the ISO all the way up to 6400 without much concern about the image quality to keep the shutter speed fast.
A sharp lens that is slow to focus is of no use to me as I like to capture birds in flight. Prior to the introduction of the EOS-1D X, Canon electronically slowed down the AF servo drive speed when either 1.4X or 2X extenders were attached to account for the loss of light, that is as 50% with the 1.4X extender and 75% with the 2X extender. The significant reduction in servo drive speed, especially with the extender 2X, limited its application for bird in flight photography. Canon changed this equation with the introduction of the EOS-1D X and series II super-telephoto lenses. When using a series II super-telephoto lens and a series III extender, the EOS-1D X user will not notice a reduction in the servo drive speed with either 1.4X or the 2X extender. (Note that is not true for any other camera or lens combination that I have used). This means that when attached to an EOS-1D X, the EF 400mm f/4 DO IS II plus EF Extender 2X III can potentially be a great combination for shooting birds in flight.
It is very difficult, if not impossible, to devise a test that can represent the true performance of camera/lens combination for tracking birds in flight. There are just too many variables. However, we can measure the servo drive speed for a static subject. To do this, I first attached the EF 300mm f/2.8 IS II to my EOS-1D X on a tripod and measured the time it takes for the lens to drive and lock focus from the minimum focus distance (MFD) to infinity at full range using an iPhone 6 Plus. I repeated this test with the EF 400mm f/4 DO IS II. Extenders 1.4X III and 2X III were subsequently added on. This test was repeated three times for each case and the values averaged. the video clips below compare the EF 300mm f/2.8 IS II + Extender 2X III with the EF 400mm f/4 DO IS II + Extender 2X III.
EF 400m f/4 DO IS II + Extender 2X III.
EF 300mm f/2.8 IS II + Extender 2X III.
The table below compares the servo drive speed for these two combinations.
There is virtually no difference in servo drive speed between these two lens for equal travel of the focus plane (note that the MFD for EF 300mm f/2.8 IS II is 2m compared to 3.3m for EF 400mm f/4 DO IS II thus slightly longer drive time). I did not measure a difference in the servo drive speed with either extender 1.4X III or 2X III. Note that with camera bodies other than the EOS-1D X the servo drive will reduce when an extender is added.
In practice, I always use far focus limit when photographing birds in flight so the servo drive time is even shorter.
This test however, doesn’t tell much about the accuracy and consistency of AI servo tracking when shooting birds in flight, in particular against varied backgrounds, which leads us to the field test.
So far the new DO lens has performed exceptionally well under controlled conditions, both in terms of optics and servo drive speed. But the real test is always in the field with avian subjects. The first thing that I noticed as soon as I started shooting with the EF 400mm f/4 DO SI II was how light and well-balanced the lens was. Right off the bat, I started shooting with the extender 2X III. On paper, this combo is ~9 ounces lighter than the EF 300mm f/2.8 IS II + extender 2X III which I have extensively used. In practice, it feels a lot lighter and easier to swing because of the shorter length and the fact that the center of the mass is closer to the camera body reducing the lever effect. It is extremely easy to track birds in flight with this lens.
Needless to say the combination of the EF 400mm f/4 DO IS II and extender 2X III performed flawlessly with static subjects delivering tack sharp RAW files with excellent micro-contrast and detail:
The examples above show typical field images from the EF 400mm DO f/4 IS II and extender 2X III. The RAW files are sharp and clean, unlike the old DO lens, there is no loss of contrast or funny-looking specular highlights in the out-of-focus areas.
With the extender 2X III attached, the maximum aperture is reduced to f/8. With the EOS-1D X, only the center AF sensor is available among with the four expansion sensors (although the user cannot individually select the expansion sensors). This means that you have to be more careful with the initial acquisition, quickly placing the bird in a smaller area compared to the case where 8 expansion points are available. At the same time, the lighter weight of the lens helps you in tracking the subject more accurately so this isn’t a big issue. The combination of the EF 400mm f/4 DO IS II + Extender 2X III is capable of some very impressive results when it comes to BIF. I have to admit, starting the field tests, I was a bit skeptical about this combination being able to produce high quality in-flight shots consistently, but after using it for about 2 months in the field, it has earned my respect.
I spent a few evenings photographing shorebirds in the San Francisco Bay area. Some shorebirds fly very fast and quite erratically so it is a good workout for the AF.
One advantage of the light EF 400mm f/4 DO IS II compared to the EF 600mm f/4 IS II is that you can hold the lens pointed at the subject in anticipation of action for a very long period of time. Some birds fly very quickly and on relatively short paths, therefore it is often very difficult to lock AF on these birds during flight. One of the techniques for capturing such birds in flight is to find a perched or standing bird, paying attention to its behavior and anticipating when it might fly. Once the lens is pre-focused on the standing bird, or slightly in front of it (for incoming shots) it is much easier to lock AF during takeoff and flight. A good example for this scenario is when birds are nesting or feeding youngsters in presence of scavengers such as gulls and crows. If you see a gull or a crow approaching nesting grounds of an American Avocet action is almost certain. This requires keeping your lens aimed at the bird in anticipation of flight or action. I can hold my EF 600mm f/4 IS II for about a minute or two before needing to lower it for a moment. With the EF 400mm f/4 DO IS II, I can hold the lens steadily aimed at my subject for much longer without feeling fatigue or getting shaky. This is a very big advantage that shouldn’t be overlooked even for skilled hand-held shooters.
Yellowlegs isn’t the easiest species to capture in flight. I had pre-focused on the standing bird in anticipation of flight.
Terns were quite active at this location feeding their youngsters with fish while holding their ground against seagulls and skimmers.
Black-necked stilt is another challenging subject.
Another classic subject is the American Avocet. I have photographed this bird extensively with many different lenses and camera bodies. Before the introduction of the EOS-1D X and the series II super-telephoto lenses, I totally avoided attempting to capture these birds in flight with a 2X extender.
One more advantage of the light-weight EF 400mm f/4 DO IS II is when tracking action with more then one bird in the frame. It is easier to keep two or more birds in the frame when action commences at high speed because swinging the lens is very easy compared to the heavier EF 600mm f/4 IS II that is my standard birding lens.
This is another example, Forster’s tern was chasing off the seagull from her nest.
Another challenging scenario for the AF is bird flying towards the camera at speed. The combination of the EF 400mm f/4 DO IS II performed well for this category as well.
For flight shots, I always set the lens focus range to far-focus for faster AF drive (shorter focus travel). When it comes to the minimum focus distance (MFD) at comparable effective focal lengths, the EF 400mm f/4 DO IS II has an advantage over the EF 600mm f/4 IS II. The far-focus MFD of the 400mm is 8m compared to 16m for the 600mm.
This is a perfect scouting lens as well, when you don’t want to commit to bringing a large super-telephoto lense to the field.
Overall, after shooting with this lens for almost two months my impression is very positive. The lens is certainly usable for flight shots with the EF extender 2X III attached to an EOS-1D X. Needless to say, as expected, the lens is extremely sharp and focuses rapidly when used bare or with the extender 1.4X III.
Incidentally, the combination of the EF 400mm f/4 DO IS II and the extender 2X III has approximately the same focal length as the EF 600mm f/4 IS II plus extender 1.4X III. It’s tempting to compare these two combos. Of course, the latter is a full stop brighter at f/5.6 (and weighs twice as much). Furthermore, it can take advantage of the the full array of the AF sensors at f/5.6. While both combos focus very quickly, when shooting challenging BIF against varied backgrounds, the EF 400mm f/4 DO IS II + Extender 2X III doesn’t deliver quite the same level of performance seen from the EF 600mm f/4 IS II + Extender 1.4X III. Some of this is due to the smaller AF expansion (4 points vs. 8 points) and some is because the AF sensor has less light to work with. The initial acquisition against a varied background when the lens is extremely de-focused is also a bit more difficult, again due to the smaller expansion area. The gap between this combination and the EF 600mm f/4 IS II + extender 1.4X III widens as the light levels drop. So while the EF 600mm f/4 IS II remains the overall king of birding lenses, the EF 400mm F/4 DO IS II opens a new chapter in compact super-telephoto lenses.
The EF 400mm f/4 DO IS II carries an equally impressive MSRP of $6899 at the time of writing this review. However, given its low production volume, the materials and technologies used to produce the lens, and its diffractive elements the price doesn’t seem out of the ordinary. Currently, this lens has no competition on the market.
Just a few years ago, I could not imagine a way to get 800mm’s of stabilized reach, with tack sharp optics and AF that is worthy for flight, out of a small backpack. The EF 400mm f/4 DO IS II is a game changer lens, at least for me. There are many locations where it’s just not possible to use a 600mm IS II prime lens. I used to take my EF 300mm f/2.8 IS II for such trips and sometimes I wished I had more reach. Well, the EF 400mm f/4 DO IS II now solves that problem. This lens is also ideal for shooting from a vehicle where there is limited space to maneuver. The winner of the head-to-head with the EF 300mm f/2.8 IS II is thus the new EF 400mm f/4 DO IS II for general bird photography. Therefore, highly recommended!
★ The lightest super-telephoto lenses on the market delivering up to 800mm of stabilized reach with fast AF (pro bodies).
★ Sharp with both EF extender 1.4X III and 2x III with no visible loss in crispness or contrast unlike its predecessor.
★ compact size, it fits in a small backpack. Easy transportation, carry-on compatible with small regional jets.
★ Rapid AF even when attached to the Extender 2X III (EOS-1D X only)
★ Far-focus MFD of 8m at 800mm.
The images in this review were processed using Canon DPP 4 software, the details of processing is explained in the DPP4 guide co-authored by Arash Hazeghi and Arthur Morris. The techniques used for capturing birds in flight are explained in the EOS AF guide. Both guides are available here
Thanks to Chuck Wesftfall, Canon USA technical adviser, for technical discussion and reference material.
Please note, I have no financial relations with Canon, nor do they pay or provide any equipment for my reviews. I purchase and review my gear independently.