Wildlife Shooters Guide to Using the Canon 1D Mark IV Auto Focus
In 2007, when the Canon 1D Mark III was released, I wrote a guide to assist users in getting the most out of its auto focus. For the next two years, I received a constant stream of emails from photographers telling me how useful that guide was to them. When the Canon 1D Mark IV became available, I started to receive emails from people requesting that I write a similar guide for the 1D Mark IV. The following is an attempt to respond to those requests. Please note that, as I gain more experience with the camera, it is likely that I will update my auto focus recommendations for the 1D Mark IV, and you are invited to come back to see those updates.
Overview of Auto Focus Modes
Auto Focus Related Custom Functions
Testing Tracking Sensitivity
Overview of Auto Focus Modes
Most wildlife shooting is going to be done in the AI Servo mode. Canon provides four choices in this mode for the 1D Mark IV.
45 Point Auto Focus
Enabling all 45 focus points and letting the camera automatically choose the active focus point can be useful in some shooting situations. When using all 45 focus points, initial focus still needs to be locked in with the center focus point before starting to shoot. Failure to lock in initial focus with the center point is a common user error that will result in out-of-focus shots. Additionally, using all 45 points generally works best in situations where the backgrounds are fairly simple, such as blue-sky for birds in flight. A busier background can make it more difficult for the camera to pick the subject out of the background, and the number of focus errors can increase
My early impression is that the 1D Mark IV seems to be able to do an very good job of using all 45 points and auto selecting the focus point in some selected situations. The advantage of this mode is that the camera will hand off focus from one available focus point to another if the subject wanders among the ring of the available active focus points. Should the subject wander beyond the circle of available points, of course, focus will be lost. On the other hand, using all 45 points means that you are allowing the camera to guess what the correct subject is. Regardless of how good the auto focus system is, the camera is going to make errors, and it is especially likely to make errors in situations where the background is more complicated. Therefore, it is suggested that using auto selection from all 45 points is not a wise choice when the background is complicated and likely to fool the auto focus system. Even with better performance in this mode compared to that of some previous 1-series cameras, I generally trust my ability to keep the focus point on the subject more than I trust the camera’s ability to guess what the intended subject is, and, thus, I don’t often use this option.
One Selected Focus Point
When the backgrounds are too busy for the camera to be able to accurately select the focus point automatically, using just one manually selected auto focus point may be more appropriate. In this mode the number of decisions the camera has to make is reduced to a minimum. But, at the same time, it requires the photographer to be precise with tracking; once contact is gone between the selected focus point and the subject, focus will be lost. Using one focus point can be a good choice when the subject fills a large portion of the frame and/or is moving slowly in a fairly predictable manner and is, thus, easier to track with a single focus point. At the other extreme, using a single focus point can be appropriate when the subject is filling only a very tiny portion of the frame and adjacent points are likely to lock onto something other than the intended subject.
One Selected Focus Point Expanded to Surrounding Points
A compromise between using all 45-points and using a single point is using a single focus point expanded to surrounding points via custom function III-8 (see below). This mode allows surrounding focus points to assist the selected focus point in achieving initial focus and also allows the camera to shift from the chosen point to any one of the six available surrounding points if the camera detects that the subject has moved from the selected point to one of those surrounding points. Similar to using all 45-points, initial focus must be locked in with the manually selected point to tell the camera on what it should be focusing, and, if the subject wanders beyond this smaller circle of surrounding points, focus will be lost. I like to use this option for much of my shooting because it gives me a bit of room for error if I am not successful in keeping the focus point on the subject. However, if the background is busy or if the subject is filling only a very tiny portion of the frame, this option can result in the surrounding points locking onto something other than the intended subject, and switching to a single focus point is likely to yield better results.
One Selected Focus Point Expanded to the Left and Right
This choice is another compromise. Like with expanding focus to surrounding points, focus must be started by locking in focus with the selected point, but the camera can hand off focus to the point either to left or to the right of the initially chosen point if the camera detects that the subject has moved to one of those points. This option is also chosen via custom function III-8.
In the 1D Mark IV auto focus system, Canon has introduced a new area focus option. In this mode, like with the others, initial focus acquisition must be done by locking in focus with a selected point. Once focus is locked in, like with the previous two options, it can be handed off to other available points if the camera detects that the subject has moved to another point. In this case, though, focus can be handed off to any of a cluster of 17 focus points surrounding the initially selected point. A further difference between this focus mode and the previous two is that, if focus is handed off to another point in the cluster of 18 total available points, a different cluster of 18 available points will now be established with the new active point becoming the center of this new cluster. Another way to describe how this option works is to say that there will always be a cluster of 18 available points, but which 18 points are included in the cluster is dynamic. Each time focus is handed off to a new point in the cluster, that new active point becomes the center of the newly established cluster. Thus, with this option, all 45 points are potentially available for use, but, at any given instant, only 18 are available. Use of area focus might help in the tracking of an erratically moving subject when it is difficult to keep a single focus point on the subject, but it also has greater potential for error with more complicated backgrounds. This option is, like the previous two options, available via custom function III-8.
Thus, an evaluation of each shooting situation can help to choose the best focus mode. When the backgrounds are less busy and less likely to fool the auto focus system, using all 45 points or using the area focus option can be an advantage, especially with a subject that is darting about and harder to keep in focus with a single focus point. However, if there is a busier background, which is more likely to confuse the auto focus system into trying to track something other than the subject, that is when switching to a single point with focus point expansion or just a single point is likely to work better. Somewhere in between those two extremes, using a manually selected point expanded to the six surrounding points might be the best option.
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1D Mark IV Auto Focus Related Custom Functions
The following will include a description of some of the major auto focus related custom functions for the 1D Mark IV. In most instances, my recommendation would be that the default settings for each custom function are likely to work the best. Canon sets the defaults as such for a reason, and that reason is that those defaults are likely to be the ones that work best in the widest variety of situations. Thus, changes from the default settings should be made only if the specific shooting situations calls for changing to something other than the defaults. It should also be noted that the reason why there are choices for various settings is because different settings are likely to work better in different shooting situations and with different techniques. Thus, there is no such thing as a “best” group of settings that applies to every situation and technique. Again, though, the default settings should give a good starting point and work well in most situations. What is likely not to work well is making major changes in multiple custom functions without a good reason for doing so.
Several of the 1D Mark IV auto focus custom functions have settings available which allow the user to optimize auto focus performance for the type of shooting being done, while others are generally a matter of personal preference or convenience. I will focus on those whose settings are the most important for wildlife and nature shooting.
Custom Function III-2
This custom function controls tracking sensitivity, and it may be the custom function that is misunderstood by more people than any of the others. Simply stated, this setting affects how long the auto focus system waits before it decides to switch focus as the camera is making a decision whether it is the photographer’s intent to keep tracking the same subject or whether the photographer wants to switch to tracking a new subject. Thus, when the subject moves from one focus point to another, the camera has to decide whether to try to keep tracking the original subject or to try to start tracking a new subject. Which setting is chosen can affect how easily focus is lost, and it can also, very importantly, affect how quickly focus is regained if it is lost.
The theory behind using a slower tracking sensitivity setting is that focus is less likely to be lost because the camera decided to start tracking something other than the intended subject; however, this custom function is, in essence, a two-edged sword because the slower settings also mean that, if focus contact is lost, the camera will wait longer to try to regain focus on the intended subject. Thus, with a faster setting, in theory, the camera might lose focus with the intended subject more frequently, but, if focus on the intended subject is lost, the camera should be able to regain focus more quickly.
With the 1D Mark III, my experience was that I had better results with the faster tracking sensitivity settings. With those faster settings, I found that I was not losing focus any more often, but, when I did lose focus, the faster settings were helping me to regain focus more quickly. With the 1D Mark IV, my early impression is that the default middle level tracking sensitivity seems to work very well. My recommendation would be to start with that default setting. If the camera's focus seems to want to jump off of the intended subject and lock onto something else too quickly, try using one of the slower tracking sensitivity settings. On the other hand, if the auto focus seems to be staying locked onto the intended subject with no problem, trying a faster tracking sensitivity setting could help to regain focus more quickly in those instance when focus is lost. Again, slower tracking sensitivity settings should theoretically minimize the instances of the auto focus switching to something other than the intended subject, but the faster settings should help to regain focus more quickly in those instances where focus is lost.
For most shooting of action, I recommend using short bursts of two to four shots. Even when I’m tracking a subject over an extended period of time and shooting a larger number of shots, I usually back off the focus and reestablish focus every few shots. The reality is that, for short bursts, the tracking sensitivity setting should make little difference because, during those short bursts, it should be very rare for the camera to have reason to decide to start tracking a new subject, and, therefore, how long it waits before switching to track a new subject is irrelevant. Where I see the tracking sensitivity setting making a difference, however, is in those rare situations where I am shooting a burst of seven or eight shots or more of fast moving action, especially when the action is at close range.
My personal experience is that situations with fast action, especially if it is moving toward the camera and at close range, are the situations where the faster settings for this custom function works best because, in those situations, contact between the subject and the focus point is more likely to be lost, and the faster settings allow the camera to regain focus more quickly. Regaining focus more quickly becomes especially important in situations where you are shooting a longer burst and there is not time to back off focus and regain focus at the expense of losing shot opportunities. When the subject may be moving a bit slower or when the subject is further away, the slower or neutral settings seems to work fine because, in those situations, contact between the focus point and the intended subject is less likely to be lost, and, thus, regaining focus quickly after it is lost is less of a priority.
At the end of this guide, I explain a procedure that can be used in helping to determine whether a faster or slower tracking sensitivity setting is likely to be more suited to one's particular shooting style.
Custom Function III-3
I recommend leaving this custom function at its default, which places the highest priority on getting the shot in focus and, then, on being able to continue tracking the subject. At settings other than the default, the highest priority is on either quickly getting the shot off or on maintaining a high frame rate. If the shot isn't in focus or if the camera isn't properly tracking, getting the shot off quickly and maintaining a high frame rate are, I think, irrelevant.
Custom Function III-4
This custom function deals with how the camera tracks focus. In the default setting, it will place priority in focusing on whatever is below the active focus point. In the “1” setting, it will place priority on tracking the subject that it has already been tracking. While it might seem, at first, that the “1” setting would be more appropriate, I and other users of Canon cameras have found that the camera seems to lose focus much more often with the "1" setting. Therefore, the recommendation is to use the default “0” setting, except in situations where objects are frequently coming between the camera and the subject.
Custom Function III-5
This custom function allows focus search to be enabled or disabled. One of the best known bird photographers has previously made the recommendation that this custom function be disabled (on previous 1-series bodies). Evidently, the recommendation to disable focus search is contingent upon the need to pre-focus, which, to my thinking, is not practical in most situations. After trying to follow this recommendation on a number of occasions, I came to the conclusion that the recommendation was ill-conceived. I found that, when I disabled the focus search, an especially high number of pictures were either completely out of focus or, at a minimum, quite soft. To make sure that nothing changed with the 1D Mark IV, I experimented with disabling focus search on the 1D Mark IV. I found that doing so led to the same unacceptable results that it did with my previous 1-series bodies. A number of other experienced and exceptional wildlife shooters that I know and/or shoot with have come to the same conclusion. Thus, my strong recommendation is to leave this custom function permanently in the default or “0” position.
Custom Function III-6
This custom function allows you to have a number of options that determine the function of the AF stop buttons that are only on a handful of long Canon lenses. Since those buttons are only found on the long lenses, this custom function does not apply at all for shorter lenses. I have generally used option 4, which allows me to use the lens buttons to switch between the servo and one shot focus modes. While I normally shoot in servo mode, there are times when the subject is static and I might want to temporarily use one shot mode. Pressing one of the auto focus stop buttons on the lens allows me to do so. Then, if the subject should start to move, all I have to do is release the button, and the camera is back in servo mode.
One other option of note available with this custom function and an option that is new to the 1-series cameras is option 7. Option 7 puts the camera into spot focus mode when one of the AF stop buttons on the lens is pressed. Spot focus mode reduces the size of the focus point and allows for more precise focusing. The spot focus mode, which was introduced on the Canon 7D several months ago, can be very useful with static subjects. It should be pointed out, though, that the spot focus mode is not likely to work well for shooting action because using this mode will make it more difficult to keep the very small focus point on a moving subject. Thus, the technique that I would use if I set this custom function to use spot focus would be to temporarily press one of the AF stop buttons on the lens to use spot focus on a static subject, but, as soon as the subject started to move, I would release the button to allow focusing to return to its previous mode.
Custom Function III-7
This custom function allows the user to make micro adjustments to correct for front or back focusing with each of the users’ individual lenses. While this should be a very useful custom function, there are a few cautions related to its use that should be noted. First, the adjustments that are made here are truly micro adjustments. They are not going to correct a lens that is grossly out of proper calibration. The full range of available adjustment seems to be equal to about the depth of field of the lens being used. However, even though the adjustments that can be made are relatively small ones, it is critical to use these adjustments in a very careful manner because, if adjustments are made incorrectly and carelessly, doing so can lead to vastly degraded performance of the auto focus system. I have seen reports of users trying to make these adjustments only using a flat test target where the entire target is in the same plane relative to the camera. Even though Canon is rather vague about how to test and adjust using this custom function, I believe that using only such a flat test target is likely to cause the user to make incorrect adjustments. If the purpose of this custom function is to correct for back or front focus, it would seem to make sense that, in addition to a flat target to actually focus on, you also need a three dimensional reference target, such as yardstick placed at a 45 degree angle to the camera or a series of C cell batteries or soup cans placed at a 45 degree angle relative to the camera to evaluate any adjustments so that you can look to see where the focus is falling within the depth of field before and after any adjustments made. That depth of field should, in general, be about 1/3 in front of the focus point and 2/3 behind the focus point. Using only a flat target placed at a 90 degree angle relative to the camera is not going to allow the user to see the depth of field, and, with only this kind of target, many of the available adjustment points will yield virtually identical results, and the user is likely to chose an adjustment level that is not, in fact, the one that is needed. Using a flat target to actually focus on and also something else at a 45 degree angle allows for both accurate focus and for checking to see where the depth of field falls. After observing how some users have carelessly used this micro adjustment, I’m confident that there are some who, by doing so, have, in effect, made their cameras incapable of focusing correctly. Further, it would seem to make sense that, when making these micro adjustments, the lens should be used with its widest aperture. With a wide aperture, the depth of field will be the smallest, and it should be easier for the user to evaluate which adjustment setting is yielding the proper results.
A further caution is that it appears that micro adjustment may improve focus accuracy at the distance at which it was set, but it may also make focus accuracy worse at other distances. Additionally, with zoom lenses, micro adjustment may improve focus accuracy at one focal length, but it may make focus accuracy worse at other focal lengths.
When I've tested several of my own lenses, I've found that each of them was virtually exactly where it should be without any adjustments, and I would not choose to make any adjustments and risk degrading auto focus performance unless I was absolutely certain that an adjustment was, in fact, really needed. Also, micro adjustment is not intended to replace proper lens calibration. If a lens is grossly out of calibration, it should be sent to Canon service for proper calibration.
Custom Function III-8
This custom function is used when a focus point is manually selected and the photographer wishes to expand that selected point to adjacent focus points, to surrounding focus points, or to the cluster of area focus points. The best setting for this custom function can vary depending on the shooting situation, and a more complete discussion of when it is appropriate to expand the focus points and when it is not can be found above in the Auto Focus Modes discussion.
Custom Function III-10
I only briefly discuss this custom function because many people mistakenly think that it determines which focus points are available when the camera is automatically selecting focus points. In fact, this custom function has nothing whatever to do with how the camera goes about focusing. All that custom function III-10 does is to determine which focus points are available via manual selection of focus points. Using a smaller number of available points can make manually selecting a focus point a faster process. Making all 45 points available for manual selection gives the user more available choices, but it can increase the amount of time it takes to actually select a focus point.
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Testing Your Tracking Speed Sensitivity
The ideal testing situation is one with fast, erratically moving subjects, especially those moving toward the camera against busier backgrounds. This situation presents special challenges for the selections made by the camera’s auto focus system and would be similar to many situations involved with shooting wildlife action.
It is critical that Custom Function III-2 be set to the most appropriate for auto focus performance. You can evaluate it to determine whether the setting is appropriate, too fast, or too slow.
Start with the setting for Custom Function III-2 in the neutral (default) setting. Shoot several bursts of pictures (using either 45 points or the center point with focus points expanded) for a total of roughly 50 frames. Look at the captures on your computer in a program such as ZoomBrowser, which superimposes the focus points on the image, and concentrate on those where the subject was still under one of the active focus points, but it was out of focus. This could be caused by either of two camera errors: (a) the camera is changing the focus to a new subject too quickly when it shouldn't be, or (b) the camera is not changing the focus to a new subject fast enough when it should be doing so.
Next, shoot several more bursts totaling about 50 shots with the same or similar shooting situation, but set the tracking speed to the fast (far right) setting. Evaluate the results; if the number of out of focus shots with an active focus point over the subject went down, that means that, at the default setting, it was not switching to a new subject fast enough. If the number of out of focus shots with an active focus point over the subject goes up, it is likely that the camera was deciding to change the focus too quickly with the default settings.
Finally, shoot several more bursts totaling about 50 shots with the same shooting situation with the tracking sensitivity set to the slowest position (far left). Upon review, concentrate on those shots that are out of focus but have an active focus point over the subject. If the number is lower with this slow setting, it indicates the default setting was changing the focus too quickly and you need a slower setting. If, however, the number of out of focus shots with an active focus point over the subject goes up, the camera was not switching the focus point quickly enough with the default setting, and you would need a faster tracking sensitivity for that shooting situation.
Once you have determined whether you need a faster or slower tracking sensitivity, try the same test with moderately fast or moderately slow options to determine a more precise setting.
Note that the only shots you want to evaluate are those out of focus and under an active focus point. Other out of focus images are due to user error and focus tracking speed is irrelevant.
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