NOTE: This article was first published over at nikonglass (https://goo.gl/6Z38uS) on the 20th February 2009
If your mind is ready to explode by all the options offered by the Nikon AF system, then read on as you just might find the following AF technique (which is good for all Nikon's) described in the first section of some interest. Further down, you will find some additional information regarding the finer options (of interest to D300/D3/D700 users) that also trouble a lot of users. I should point out that this is an old and tried technique that the majority of Nikon pros have been using for a number of years. I believe it to be the most important focusing technique that all Nikon users should try at least once. If you manage to learn it and use it, then I am sure you will never look back. (Note: This article was originally written in 2008 for Nikonglass with the D300 in mind, later revised in 2009 to include the D700 - but should be good for most Nikons)
The ability to customize a camera to ones shooting style is a great feature, but the options available to customize the AF system on most Nikons are just too complex. Unfortunately the Nikon AF system is designed with compatibility on the top of the list and not performance. So this is why we have a multi-position selector both on the front and rear of the camera body, a plethora of custom menu settings, switches on most lenses, a thumbwheel and plenty of AF points to choose from. Not exactly a straightforward, no-need to remove eyes from viewfinder type of method for focusing. Trying to select the best options for the myriad of subjects is mind boggling and nerve racking and this is why the majority of amateurs settle for single point AF. The following technique will give you the freedom to focus anyway you want without ever needing to remove your eye from the viewfinder.
Now, with the above selections set, you press the AF-ON button to focus. If it’s a static subject you simply press with your thumb, focus and let go to lock the focus, recompose if you need to and fire the shot. If you are shooting action, your thumb stays pressed against the AF-ON button and you fire at will. If you desire precision for a portrait or macro session, then don’t engage the AF-ON button and focus manually. So simple yet so effective - you get all three focusing modes (continuous, single and manual) using just your thumb and without the need to remove your eye from the viewfinder. It’s a shame so many people shy away from this technique. You should try to utilize the AF-ON and I’m sure you will be thankful in the end.
So far the above was easy for you because all the options were already selected for you – all you had to do was to decide whether to try this way of focusing or not. In Part 2 though, you are required to make some choices. This is because the rest of the options available for the AF system have more to do with your personal style and your chosen subject. I will guide you through the two most asked about.
Center AF point: The most misunderstood feature of the Nikon AF system is the ability to choose the initial focusing point. I think too many photographers abuse this option. You don’t need to be chasing a subject with your thumb trying to select an appropriate AF point. In my attempt to eliminate as many variables during my shooting, I have excluded the thumbwheel altogether. With the center AF point selected, the thumbwheel then can be locked for nearly 95% of all shooting situations. The big benefit is that you have one more less dial to worry about. Now some of you may ask, what about focusing off center for better compositions – well you still can since you focus initially with the center AF point and then recompose while the camera changes AF points by itself in an attempt to follow the subject. Plus don’t forget you can always let go of the AF-ON button to lock the focus and again recompose.
15 cross-type AF points: I should remind most of you that out of all the 51 AF points, the 15 that are concentrated in the middle three columns are made up of the cross-type AF sensors. These are more powerful, precise and work more reliably than the others under low light conditions. So initiating focus using any of these cross-type sensors is the more reliable way of shooting, especially for sports. So with center AF point selected as your starting position, the camera can then track the subject using the rest of the available AF points if needed. You can now see why Nikon kept all cross-type focus points in the center of the frame – so as to not lose the focus on the subject as soon as it moved off the center AF point. Let the camera utilize the other cross-type points to your advantage as you, the photographer, can later crop the frame a little to help for a more dynamic composition if needed.
Difference between 51 and 51/3D: With all 51 points you choose the initial focus point and the camera will follow the action utilizing all 51 points to track the subject as it leaves the initial focus point. With 51/3D tracking the camera will utilize information from the matrix metering sensor as well to help pick colors from the subject. This can be more effective if you have a distinctive subject (color wise) and a neutral and different colored background. 51 AF points with 3D tracking may be the future but for mow its underpowered (needs a faster processor) and buggy (needs more advanced and intelligent software)
How many AF points: No matter how much one tries to explain his experience with the AF points, it’s all pretty much what works on the day. I usually find myself using either 9 or 21 points no matter what I’m shooting so Custom setting menu A3 is my most often used setting and this is why its first on the “My menu” list as well.
Sports with busy scenes: I might be shooting at a soccer game with a long tele so my first choice would be 9 points. But at some point while I’m shooting, I find myself shooting a lot of close shots of a single player so I might find that I need the space coverage of 21 or even 51 points so I can follow focus the face easier.
BIFs and motor sports: For easy subjects such as BIFs and motor sports you could try 51 points with 3D tracking. This is the future and I can’t wait for the next generation of Nikon cameras that will feature the next generation of this technology. You will have more misses than you would like and you probably shouldn’t be using this option for a paid assignment, but when you do get it to work you will be amazed by the results and wishing it worked like that more often. Of course if you can get it to work reliably and consistently, then by all means use it professionally (I know a few who are!). But in all seriousness, for more reliable results start off with 21 or 9 points. And don’t forget that fewer AF points also mean faster focus acquisition and better lock-on so if the action is very fast and you can feel the camera having a hard time locking-on, try fewer points.
Wedding and street: Personally I again start off with 9 points and rarely find myself deviating from that. I use the focus and recompose technique a lot with weddings utilizing the above setup of course. It’s so easy and I get nearly 100% focused results every time. With the center AF point sensor locked, I always know where it is and don’t have to fumble with the thumbwheel to get it in position. The only time I may choose a different AF point is if I want to track a moving subject that’s off center.
So as you can see, there is no one recommendation for a certain situation. The question on how many points boils down to experience and trial and error. It would be safe to say though, that most pros are usually jumping between 9 and 21 points. Do remember though that for the best AF performance use the least points needed. The more predictable the action, the less points are needed to be active and your results will be more precise.
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