Canon EF 400mm f4 DO II Lens Review (BIF)


400mm must be a popular focal length, as Canon covers it with five current L (premium) lenses in its line-up (see Table 1). My primary interest in the long telephotos is for photographing birds. Clearly there are many other uses, but bird photography is very popular, arguably the most popular use for these lenses. Others have put this lens on an optical bench to measure its optical qualities and resolution. I won’t be repeating that information here as I don’t have the expensive equipment required for these careful optical measurements                                                                            (e.g.  ).  My take away on optical quality/resolution potential is that the new 400mm DO II about as good as it gets at  f~4. I say potential sharpness because shooting in the field is much different from shooting on an optical bench, and many additional factors can come into play that will impact  image sharpness. When shooting a moving target (flying bird), these other factors usually overwhelm the “potential” sharpness of the lens and one is left with a more or less sharp image that is at least equally dependent on the autofocus and tracking capability of the camera body. The important lens characteristics that figure into the sharpness equation (beyond inherrent lens sharpness) is the maximum aperture, autofocus speed, IS modes, and weight. Its very difficult to separate the contribution from each of these factors, but it is fairly clear how each affects final sharpness in comparison with other lenses of the same focal length.

The current Cannon L glass:   (Table 1 )

Canon Lens                       Weight          Length          IS          U.S. Price

400mm DO II f/4                 74 oz             9.2 in         Yes         $6,900

400mm f/5.6                       44 oz              10.1 in        No        $1,250

100-400mm f/4.5-5.6 II       56 oz         7.6 - 10.5 in    Yes         $2,200

400mm f/2.8 II                    136 oz            13.5 in        Yes        $10,000

200-400 f/4                         128 oz             14.4 in       Yes        $11,000

This is a very diverse group of lenses for 400mm coverage from one manufacturer.  Weight varies by a factor of 3, and price varies by a factor of 10. Keep in mind that the prices will change with time and the lengths shown are without the lens hood attached or extended.

Diffractive Optics, or what Canon calls DO is an unusual lens configuration that can allow a lens of some tele focal lengths to be made somewhat shorter and has the potential to control Cromatic Aberations somewhat better. The Canon 400mm DO lens is the third generation of this technology and it appears that Canon has really mastered the technical aspects of the design with this iteration. To distinguish the DO lens line from other Canon lenses a green ring is used. Technically the 400mm DO lens is not a L type (red ring) but certainly the build and optical quality is there. I don’t worry too much about the magic that Canon uses to build their DO lenses, but rather concentrate on the practical benefits.

When photographing stationary (or nearly so) birds from a tripod, any of these lenses will do an admirable job. The lenses with wider apertures will isolate the subject from the background more completely because of the narrower depth of field with wider apertures. However, a narrow depth of field can work against the photographer in some situations. 

Consider the depth of field table below to get some idea of how narrow the in-focus region is:

     400mm Lens    Depth of Field     (Table 2 )            f/4 Prime w/1.4 X extender

Aperature       Distance      APS-C       Full Frame            APS-C           Full Frame

2.8                      25 ft            1.4 in              2.3  in

4                                            2 in                 3.2 in

5.6                                        2.9 in               4.6 in                 1.3 in               2.1 in

2.8                      50 ft           6 in                  9.5 in

4                                           8.4 in              13.3 in

5.6                                        12. in              18.8 in                 5.3 in                8.3 in

2.8                     100 ft         24.2 in             38.3 in

4                                          34.3 in             54.1 in

5.6                                       48.5 in             76.7 in                 21.5 in              34 in

For birds that are relatively close to the photographer, say 25 to 50 feet, the depth-of-field is frequently less than the bird’s dimensions. In this situation, some part of the bird will have somewhat soft focus no matter how good the photographers technique. Using an APS-C camera body or 1.4 X extender narrows the depth-of-field even more. Its necessary to keep this in mind when evaluating photos. Any observed softness in an image may be from motion of the target, motion of the camera/lens, missed focus, or simply  parts of target outside the depth-of-field of the focus plane.

Speaking of the focus plane, the “window” that your lens sees with a super telephoto lens may be smaller than you think. A 400mm lens on a full frame camera covers a 6.1 degree diagonal angle (from corner to opposite corner). Turning this angle into a window dimension at any given distance is a fairly simple trigonometry calculation. Of course the angle of view is reduced with an APS-C camera or tele extender. At a 50’ distance from camera to bird, using an APS-C camera and 1.4 x tele extender, the window dimension is only 2 ft horizontally and about 1.3 ft verticaly looking through the view finder. Finding a fast moving bird in that small window through your view finder takes some practice.

Off the Tripod

The raison d’etre or “reason to be” for the Canon 400mm DO lens is it’s relatively compact size and light weight for an f/4 aperature. Looking at table 1, the DO is not the smallest or lightest lens in the group, but it does have Image Stabilization (IS) and an f/4 aperture, unlike its two smaller siblings. The 100-400mm f/4.5-5.6 zoom does have IS. As I mentioned earlier, all the lenses in Table 1 are admirably sharp, but the DO is slightly sharper than the two lighter lenses. It is my contention that to photograph “Birds in Flight” (BIF) effectively , one needs to hand hold the lens. I know there are a few exceptions to this assertion (like fixed humming bird set-ups or attempting to use a gimbal tripod head) but it’s mostly true (at least for me). In addition, if you are carrying a lens for a distance then compactness and light weight are to be cherished. If back packing, I would likely take one of the two lightest lenses, and not the DO.

For many years I have used the Canon 400mm f5.6 prime lens as my go to lens for birds in flight. I’ve always used it on a full frame camera body  because that is what I had. I have not been using the TeleExtender 1.4 X because the reduction in autofocus speed and reliability was not worth it for me. I’ve had fair success with the lens as evidenced by some of the BIF images in my galleries. The 400mm f/5.6 is a wonderful lens to hand hold. Its weight is such that it can be held all day without fatigue and moves to the eye effortlessly for the fast action that is BIF shooting. On my Canon 5D II and 5D III bodies it autofocuses quickly and stays locked-on when in servo focus mode. I’ve always shot with the lens wide open and have been rewarded with an acceptable number of sharp and  in focus keepers. Most of my shooting has been for large water birds. These birds tend to fly on predictable flight paths (generally straight) and many are physically large. I know there are exception (like some crazy ducks). 400mm on a full frame camera usually filled enough of the frame for me to be able to make a decent print.

For a more challenging water bird, I have frequently tried my hand at photographing Terns. In flight, the Common Tern is about 1 foot in length and has about a 30 inch wing span. The Tern’s flight path is frequently erratic as the bird hunts with changes in direction, speed, and altitude. Therein lies the challenge. I’ve had only slight success with this bird (after many shots) using the Canon 400mm f5.6 on the 5D II and 5D III.

On a recent trip to Chincoteague National Wildlife Refuge I decided to try out my new Canon 400mm DO lens with my also new Canon 7D II. Before leaving I performed my usual AFMA adjustments for the lens with and without a telextender using FoCal software. The combination of an APS-C camera body and 1.4 x extender was a bit of an eye opener for me. I more than doubled (2.24 x) my usual effective focal length compared with my usual 400mm f/5.6 on a 5D III body. The weight of lens and camera body also increased noticeably.

First the weight increase. Because I was moving from a lighter rig to a heaver rig, I wasn’t happy about the weight increase. For me, it was noticeably more tiring using the 400 DO for several hours at a time. The ease of bringing the rig to my eye quickly, finding the bird in the finder, and tracking while shooting was more difficult than I was accustomed to. However, it was very doable. After several days of use, I found that it did get easier, though never quite as easy as with my old rig. Now keep in mind that I was also more than doubling my effective focal length relative to my old rig and this also generated some surprises. Holding what is effectively a 900mm rig in your hands for BIF shooting is a lot of fire power. For me, it became intoxicating. I was now able to fill the frame with a tern. In some cases, the tern actually extended beyond the frame on all four sides.  Amazing!!!     I also noticed that there was more apparent jitter or wobble in my ability to hand hold the frame on the fast flying bird. It was certainly more noticeable than was the case with my old rig. I began to wonder if this was an issue of increased weight causing me to wobble more as I attempted to hold focus on a flying bird?  Additional weight probably is a factor, but not the major factor. Any unsteadiness that I have is amplified by the 2.2 x magnification increase of this rig. Even if my natural wobble did not change, the extra magnification made it appear worse and in fact more than double.

So, how much wobble, or unsteadiness in holding a camera and lens to one’s eye is normal?  Like almost everything else, this has been studied and measured:

None of the cameras used in the linked study were as big and heavy as a 400mm DO, but still there is some indication of hand held unsteadiness as a function of time period. The curves of angular wobble are still headed up at 1 sec of time. Tracking birds in flight usually occurs over several seconds so some extrapolation may be necessary. At one second the angular wobble on the linked site’s graphs was about .12 degrees (one sigma). Two sigma might be called a near extreme excursion, say .25 degrees of wobble in one second of hand holding. For the 900mm set up (APS-C and 1.4 x teleconverter) this works out to about 16% of the vertical frame height. In other words, looking through the view finder, an average person hand holding this rig would see the image wobbling up and down by about 16% of the field of view. This number seems a little low to me after tracking birds with my camera for several hours, and I would say 25% would be a closer number. I’m sure the ability to hand hold with little shake is a function of the person, technique, and practice, so your milage may vary from mine. Some people actually horse around the 400mm f/2.8 at nearly twice this weight.

Why is wobble important?  To some extent, it’s important for getting a sharp image. Assuming AF is correct, then motion of the target within the image frame causes motion blur. One compensates for motion blur by using a high shutter speed (like ~ 1/2000 sec or faster with the APS-C and 1.4 x rig) and lens Image Stabilization (IS).   IS should help to compensate for your wobble motion during the exposure period. The 400 DO has 3 modes of IS settable via a switch on the lens. For BIF shooting, mode 2 compensates continuously, while panning, in the direction perpendicular to the panning motion (e.g. compensates for up and down wobble while panning sideways) with the shutter button half depressed. Mode 3 IS compensates at the instant of shutter release (rather than continuously) for the same wobble motion as in Mode 2.    Mode 1 is for still shots and little or no target movement. So far, I’ve been using Mode 3 while shooting birds in flight. It’s difficult to determine the IS effectiveness at high shutter speeds and I don’t yet have any comments about the high shutter speed effectiveness of IS on the 400mm DO lens. A second reason to be concerned with camera/lens wobble while hand holding is ones ability to hold one or more AF points on the desired part of the target. Lets say you want the head of a bird to be the sharpest part of the image and select one, or a few, AF points to place over the head of the bird while clicking the shutter. The first issue is where to put these points in the frame for a bird that may approach from several directions and show different body aspects at these angles. Perhaps you have mastered the art of fast switching AF points and can adjust quickly for whatever comes your way. Then, you have to be able to hold on the bird well enough to put the AF points at the spot where you want them on the target. The bird is not always kind enough to fly in a straight line and you have vertical wobble of up to a quarter of the frame. I’m not going to tell you this is easy to do because it’s not. An element of luck is involved and shooting a lot of images enhances your chance of getting a few frames that you like. Dropping back to a straight 400mm DO without teleconverter on a full frame camera certainly makes this easier, but also makes the bird smaller in the frame.

The Camera

Field performance of a lens cannot be separated from the performance of its mother camera body. The lens offers potential by providing a sharp, bright, and possibly stabilized images for the camera body to analyze, process, and record. For shooting birds in flight (BIF) the camera body auto focus (AF) operation and performance is paramount. Consider the difficulty of what has to be accomplished by the camera body:

1. The camera AF system in servo (tracking) mode has to continuously adjust the AF distance to the target while the target is moving in a relatively straight line but with some jinking up and down and some random velocity changes (depending on the bird and its behavior and reactions to the environment). Based on the camera’s instantaneous analysis of this target movement a prediction is made as to what the AF distance should be at a time in the near future when the shutter could open. There is a small delay after pressing the shutter release button until the shutter actually opens. Predictive AF predicts where the target will be when the shutter opens.

2. The camera manufacturer (Canon in this case) understanding that there are many factors that can affect the quasi-unknown motion of targets allows the camera user (you) to make tweaks to the AF algorithms based on your best guess (or deep understanding) of the target’s potential motion. These tweaks are found in the camera’s menu as AF cases. These tweaks may help or hurt the camera’s ability to accurately AF depending on how the target actually moves.

3. The target, a bird in our case, shows different aspects and body parts to the AF points as a function of time. If you are looking side on to a bird in flight, the wings will frequently be flapping up and down. If an AF point is on the wings, the closest distance to the bird will be varying at the wing beat frequency by about 1/2 the bird’s wing span. Consider the tern with a 30 inch wing span and thus a 15 inch sinusoidal variation in focus distance as seen by the camera with each wing beat. From table 2 above, the DOF is only a few inchs at best for close distance birds. Its easy to see how AF distance can be calculated slightly incorrectly and a soft image result.

4. Let’s not forget camera/lens wobble, discussed above,  that is moving the AF points about the image due to hand holding unsteadiness. Some of these AF points land on the sky (infinity), or background trees, and some move about on the bird’s body. Depending on the size of the bird and its wingspan, the movement of AF points can easily change AF distance more than the DOF with wobble motion. If multiple AF point are selected by the user, the camera has to switch AF points intelligently to adjust for the wobble. If a single point is selected the camera has to deal with the point alternating between infinity (sky distance) and the bird distance as the camera wobbles and the bird jinks.

All the lens has to do, to AF, is take the AF command from the camera body and quickly adjust focus distance to the commanded distance. If IS is on, the lens also attempts to stabilize the image based on sensed motion.

The quality of the Camera Body AF system is a very important player in the final result. I currently have two recent Canon bodies that I’m testing on. They are the 7D II and the 5D Mk III. Results on other bodies may be better or worse than my findings. Generally, Canon bodies are known to have outstanding AF capabilities. The pro bodies will of course be better than consumer grade bodies.

AF on the 7D II + 1.4 x III

The Canon 400mm DO II lens has an AF distance limiter switch. Use it when you can! With APS-C plus Teleconverter the AF performance slows down from the no teleconverter configuration. With an effective 900mm focal length, it will be fairly rare to shoot flying birds closer than 25 ft because the bird will likely be as large or larger than the frame. Hence, setting the distance limiter to the (8m - infinity) position will help the AF to close in on the correct distance. The other thing that helps is to anticipate the pick-up point where you will start to AF on a bird and to pre-focus at that approximate distance. When using these techniques, I had little problem with acquiring initial AF.  Sometimes when not using this technique, the AF went to a completely out of focus point and stopped searching for correct focus. I had to repeatedly push my AF button (moved to the rear camera face) to get the camera to resume searching for focus. This was disconcerting at best because focus was so far off that the bird was not obvious in the view finder. Trying to track a bird and hit focus when the lens is way off focus is not what you want to be doing. The 7D II has a menu item that allows the user to set “continue to AF when focus is impossible” to on or off. For this situation, I always leave it on; nevertheless, sometimes the camera would stop trying to find focus when in a completely out of focus condition.

AF on the 7D II

AF with the Canon 400mm DO II lens without an telextender is much the same at the case above. The primary difference in handling is that focus locks onto the bird noticeably faster and hunts for focus less noticeably. Also, the tendancy to sometimes go completely out of focus and not come back without repeatadly punching the rear camera focus button does not happen as often. In short, the camera and lens “pick-up” the bird more quickly and reliably without a telextender. This is no surprise and is true for other lenses as well.

I still have not collected any significant data for the 400 DO mounted on my Canon 5D III. I’m finding that for BIF the extra reach of the 7D II is desirable almost all of the time and I can’t force myself to use the 5D III.  If a situation arises, I will post the data.


I am going to include sample images as a part 2 of this review. This may be what you are really looking for and I will get to them. I have nearly a thousand Tern in flight  images collected on the 7D II + 1.4 x combination so far and will be collecting more with other combinations and bird varities as I am able to get into the field. It takes awhile to sort and make sense of what I’ve got so far.

Reviewing the BIF images from my Chincoteagure National Park, I put each image into one of three groups.

Group 1:  Sharp images.  This group has the smallest variation (image to image) in sharpness. I reviewed the images in the edit window of Adobe Lightroom and if it looked sharp there for the full image, I zoomed-in to a 1:1 magnification. If it still looked sharp, the image went into group 1. The acceptable variation was from “this is as sharp as an image gets in this Lightroom View to, very slight out-of-focus sharpness that could only be seen at 1:1 magnification”. Rarely was the image sharp all over the frame. These were all shot at an effective f/5.6 aperture and the DOF was narrow (see discussion above about DOF). I was mostly looking for a sharp eye and bill. Occasionally if the eye and bill could not be seen due to the aspect angle, then a sharp wing was used. I believe that most photographers would have considered this group of images to have focus nailed.

Group 2: Almost sharp images. This group was the largest in number. Images in this group looked sharp in the edit window of Adobe LR, but when zoomed to a 1:1 magnification, some focus bluring was evident. If the full frame was printed on an 8 x 12 inch paper print, most would have looked sharp and in focus to a casual observer. Again, I was mostly looking for a sharp eye and bill. Some of these images could have had some motion blur instead of focus blur. Sometimes its hard to discern the difference. However, I did keep shutter speed high enough that there should not have been motion blur (except possibly some wing tips).

Group 3: Significantly blurred images. This group had the largest variation in sharpness and was the smallest group in number of the collected images. Out-of-Focus was evident in the full frame Adobe LR edit window. The variations ranged from slightly worse than Group 2 images to severely out-of-focus images.

I did not edit out any of the BIF images that were collected. This means that some had partial birds in the images due to poor framing at the time of “click” on my part. In retrospect, after looking at the images, some must not have appeared sharp in the viewfinder at the time I took the picture (using servo focus mode) because of how blured the image was. Also, exposure was not always acceptable with exposure misses mostly due to underexposure on some back lighted images. In general, all lighting conditions were encountered over several days with some overcast, some front lighting, some back lighting, some side lighting and some top lighted. I can’t really say that any particular lighting condition was better or worse for ability of the lens/camera to focus. So, all the cats and dogs were included in the total collection evaluated. Although I did not count the number I would estimate that about 85% of the BIF images evaluated were terns. Other birds that happened onto my location included egrets, ibis, gulls, osprey, ducks, geese, herons, shore birds, ravens, etc.

The total number of BIF images evaluated were 848.  The group break-down was as follows:

Group 1:  33%

Group 2:  57%

Group 3:  10%

Certainly not all of the Group 1 images would be considered “keepers” in the sense that focus sharpness is only one aspect of a “keeper” image.

More Images

In December, 2015 I spent another week shooting with the Canon 400mm DO II and 7D II. This time I was in Florida at Merrit Island National Wildlife Refuge and Sanibel National Wildlife Refuge. The primary difference in this birding trip and the prior one to Chincoteague is that instead of Terns, I was primarily shooting larger water birds in flight. These included various egrets, herons, ibis and pelicans. Because these are larger birds, they were larger in the view finder creating an opportunity to shoot mostly without my 1.4 x telextender. These large lumbering birds do not jink and turn as unpredictably as the terns did. However, there were some instances of misfocus in cases where, in my mind, focus should have been a slam dunk. I can’t currently explain this and will be looking for factors that cause this phenomenon in the future. Over the week of shooting many different  lighting conditions and bird approaches (cross flight and head-on aspects) presented themselves. I’ve again condensed my autofocus (AF) success results into the three groups described above. Those results for the baseline 400mm DO II only are: (628 images evaluated)

Group 1:  49%

Group 2:  34%

Group 3: 17%

I did shoot some on this trip with the 1.4 x extender and those results: (290 images evaluated)

Group 1:  38%

Group 2:  46%

Group 3:  16%


My conclusions may be what you are looking for.  I can say that the 7D II + 400mm DO II lens + 1.4 x combination is amazing in terms of its reach and ability to capture outstanding images. My personal experience is that about 1/3 of the images that you shoot will be excellent in terms of sharply focused images. Obviously the conditions you are shooting in and the photographer’s ability and experience will affect your personal keeper rate.  Having the equivalent of 900mm of fire power in one’s hands that can AF quickly and capture sharp images is an eye opener. The AF hit rate (Group 1) with this combination has not been quite as good as I had hoped, but it is very acceptable. That is, you will bring home many shots to be proud of. If you are in a situation where you can shoot with the bare 400mm DO II lens, then you can expect your sharp image keeper rate to improve to about 50% of shots. I’m sold on this lens and it has now become my primary BIF lens.

This lens evaluation has been focused (no pun intended) on birds in flight. That is where this lens outshines most others. Clearly there will be many opportunities presented where the birds are essentially stationary and with this lens mounted you still have a killer rig. I found that when shooting stationary birds the AF hit rate is close to 100%. Just keep the shutter speed up and hand holding for the stationary birds will give you plenty of mobility and capability to get those fleeting shots when a bird lands nearby. If the situation allows you to get onto a tripod, you can drop the shutter speed.

© Ronald Brunsvold 2014, All rights reserved