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Camera Reviews

Autofocus Custom Settings a1 to a8

Darrell Young (DigitalDarrell)

Keywords: nikon, d800, custom, settings, camera, bodies, af, focus

The Nikon D800 and its later sibblings D810 and D850 have a very powerful autofocus system with features not seen on earlier Nikon D-SLR's.

So, with great power, comes great responsibility, isn't that how the saying goes? In this article, you'll have a great read about all your Custom AF-Settings on the D800, many of those also relates to the later Nikon D810 and D850 cameras.

The article is refined to simplicity from an excerpt from Mastering the Nikon D800 by Darrell Young, published by NikoniansPress/Rocky Nook. Here, we talk about the Custom Setting Menu and eight distinct Custom Settings just for the autofocus system. So grab a nice cup of joe or tea, whatever hits the spot, and enjoy!

Let’s consider each of the Custom Settings and see how best to configure the Nikon D800 camera for excellent results.


Custom Settings a1 to a8

You’ll find eight distinct settings within the a Autofocus menu in the D800.

  • a1 – AF-C priority selection
  • a2 – AF-S priority selection
  • a3 – Focus tracking with lock-on
  • a4 – AF activation
  • a5 – AF point illumination
  • a6 – Focus point wrap-around
  • a7 – Number of focus points
  • a8 – Built-in AF assist illuminator

This first sub-section is about how to configure the autofocus system in various ways. The whole process is rather complex—and important for good photography. I thought autofocus and related functions important enough that I’ve included in this book an entire chapter dedicated to Autofocus (AF), AF-area modes, and Release modes. It covers autofocus and its supporting functions in much deeper detail. Please be sure to read that chapter well.

Custom Setting a1 – AF-C Priority Selection

(User's Manual – Page 281)

AF-C priority selection is designed to let you choose how your autofocus works when using Continuous-servo autofocus mode (AF-C).

Make sure you understand how this function works. If you configure this setting incorrectly for your style of shooting, it’s entirely possible that a number of your pictures will be out of focus. Why?

Well, if you’ll notice in figure 4.2, screen 3, there are three specific selections:


  • Release – If the image must be taken, no matter what, then you will need to set AF-C priority selection to Release. This allows the shutter to fire every time you press the Shutter-release button, even if the image is not in focus. Releasing the shutter has “priority” over autofocus. If you are well aware of the consequences of shooting without a focus guarantee, then use this setting to make your camera take a picture every time you press the Shutter-release button. Your camera will shoot at its maximum frames per second (FPS) rate because it is not hampered by the time it takes to validate that each picture is in correct focus. You'll need to decide whether taking the image is more important than the image being in focus. We’ll discuss why the Release and Release + focus functions exist in an upcoming section titled Using Custom Settings a1 and a2.
  • Release + focus – This function slows the frame rate for improved focus when the light is low or the subject has little contrast with its surroundings, but it still allows the shutter to fire even if it cannot find a good focus point. Release still has priority over Focus, but the camera tries to focus before releasing the shutter.
  • Focus – This setting is designed to prevent your camera from taking a picture when the Viewfinder’s green in-focus indicator is off. In other words, if the picture is not in focus, the shutter will not release. It does not mean that the camera will always focus on the correct subject. It simply means that your camera must focus on something before it will allow the shutter to release. Nikon cameras do a very good job with autofocus, so you can usually depend on the AF module to perform well. The Focus setting will drastically increase the chances that your image is in correct focus.


Figure 4.2 – Choosing a shutter-release priority for AF-C mode

Here are the steps to select a shutter-release priority when using AF-C mode (figure 4.2 above):

  1. Select an Autofocus from the Custom Setting Menu and scroll to the right (figure 4.2, screen 1).
  2. Highlight a1 AF-C priority selection and scroll to the right (figure 4.2, screen 2).
  3. Choose one of the three settings from the menu, with full understanding of what may happen if you don’t choose Focus. If you have the experience to use depth of field to cover autofocus, in case of slight focusing errors, or if you use the AF-ON button instead of the Shutter-release button for initiating autofocus, you may do well with AF-C priority selection set to Release or Release + focus. Test this carefully.
  4. Press the OK button to select your shutter-release priority.

Settings Recommendation: Since I’m not a sports or action shooter, I choose Focus. Even if I were an action shooter, I would choose Focus. Read the section called Using Custom Settings a1 and a2 before you make your final choice. The safe choice is Focus.


Custom Setting a2 – AF-S Priority Selection

(User's Manual – Page 282)

AF-S priority selection is very similar to AF-C priority selection. It too allows you to choose whether the camera will take a picture without something in focus. With this function, you set a shutter-release priority for Single-servo autofocus mode (AF-S). Set it wrong and many of your pictures may be out of focus. I choose Focus priority when using AF-S.

There are two modes to choose from (figure 4.3, screen 3):

  • Release – A photo can be taken at any time, even if not in focus. This can lead to images that are out of focus, unless you manually focus each time you take a picture. The camera’s priority is releasing the shutter when you press the Shutter-release button, and it will do so even if nothing is in focus.
  • Focus (default) – The image must be in focus or the shutter will not release. This means that the shutter won’t release unless the Viewfinder’s green in-focus light is on. This is the closest thing to a guarantee that your image will be in focus when you press the Shutter-release button. However, if you are focused on the wrong part of your subject, the camera will still fire.


Figure 4.3 - Choosing a shutter-release priority for AF-S mode Camera Screens.

Here are the steps to select a shutter-release priority when using AF-S mode (figure 4.3 above):

  1. Select a Autofocus from the Custom Setting Menu and scroll to the right (figure 4.3, screen 1).
  2. Highlight a2 AF-S priority selection and scroll to the right (figure 4.3, screen 2).
  3. Choose one of the two settings from the menu, with full understanding of what may occur if you don’t choose Focus (figure 4.3, screen 3).
  4. Press the OK button to select your shutter release priority.

Settings Recommendation: Once again, I choose Focus. I love pictures that are in focus, don’t you? When I don’t want the camera to care about autofocus over shutter release, I’ll just flip the switch to manual on the camera or lens and focus where I want. Up next is the section called Using Custom Settings a1 and a2. Read it well!


Using Custom Settings a1 and a2

Before we proceed to the next Custom Setting, please consider the following special information.

Release priority vs. Focus priority – Two of the more important functions in this Custom Settings chapter are a1 and a2. I added this special section so you'll understand why you must pay very close attention to these two settings.

Focus priority simply means that your camera will refuse to take a picture until it can reasonably focus on something. Release priority means that the camera will take a picture when you decide to take it, whether anything is in focus or not!

Now, you might ask yourself, "Why is there such a setting as Release priority?"

Well, many professional photographers shoot high-speed events at high frame rates—taking hundreds of images—and use depth of field (or experience and luck) to compensate for less-than-accurate focus. They are in complete control of their camera's systems and have a huge amount of practice in getting the focus right where they want it to be.

There are valid reasons for these photographers not to use Focus priority. However, most of those same photographers do not let pressing the the Shutter-release button halfway down start autofocus either because the focus could change every time the Shutter-release button is pressed. They set a4 AF activation so that the autofocus doesn't even activate until the AF-ON button is pressed. They then use the AF-ON button exclusively for autofocus and the Shutter-release button to take the picture. They separate the two functions instead of using the Shutter-release button for both.

You need to ask yourself, "What type of a photographer am I?"

If you are a pro shooting hundreds of pictures of fast race cars, Focus priority may not be for you. However, for the average photographer taking pictures of his kids running around the yard, deer jumping a fence, beautiful landscapes, flying birds, portraits, or a bride tossing a bouquet, Focus priority is usually the best choice. For most of us, it's better to have the camera refuse to take the picture unless it's able to focus on our subjects.

When you’re shooting at a high frame rate, Focus priority may cause your camera to skip a series of out-of-focus images. It will slow your camera's frame rate so that it will not reach the maximum 4 frames per second in some cases. But, I have to ask, what is the point of several out-of-focus images mixed with the in-focus pictures? Why waste the card space, add shutter wear, and then have to weed through the slightly out-of-focus images? Especially with the images sizes the D800 creates!

Pay special attention to these two settings. You will need to decide—based on your style of shooting—whether you want your camera to refuse to take an out-of-focus image. If you set a1 and a2 to Focus priority and you try to take an out-of-focus image, the Shutter-release button will simply not release the shutter. The green in-focus indicator in the Viewfinder will have to be on before the shutter will release.

Settings Recommendation: I set both a1 and a2 to Focus priority. I’m not a high-speed shooter, so I don't need my camera to take a picture "no matter what." What good are out-of-focus images?
I discuss this even more in the chapter titled Autofocus, AF-Area, and Release Modes in the NikoniansPress Mastering the Nikon D800 book.


Custom Setting a3 – Focus Tracking with Lock-On

(User's Manual – Page 283)

Focus tracking with lock-on allows you to select the length of time your camera will ignore an intruding object that blocks your subject.

In other words, let’s say you are focused on a bird flying past you. As you pan the camera with the bird’s movement, the autofocus system tracks it and keeps it in good focus. As the bird flies by, a road sign briefly interrupts the focus tracking as the bird moves behind it and then reemerges. How would you feel if the bright, high-contrast road sign grabbed the camera’s attention and you lost tracking on the bird? That would be quite aggravating, wouldn’t it?

The D800 provides Focus tracking with lock-on to prevent this from happening. The “lock-on” portion of this function helps your camera keep its focus on your subject, even if something briefly comes between the camera and subject. The camera locks on to your subject doggedly if this function is enabled.

Without Focus tracking with lock-on, any bright object that gets between you and your subject may draw the camera’s attention and cause you to lose focus on the subject.

The camera provides a variable time-out period for the lock-on functionality. Lock-on time-out allows an object that stays between the camera and your subject for a predetermined length of time to attract the camera’s attention. You can adjust this time-out according to the delay time period that works best for you. Plan to experiment a bit so that you can determine what is best for your style of shooting. The factory default is Normal, which I’ve determined from my own testing seems to be about a 1-second delay.


Figure 4.4 – Focus tracking with lock-on


Here are the screens and steps to configure Focus tracking with lock-on (figure 4.4 above):

  1. Select a Autofocus from the Custom Setting Menu and scroll to the right (figure 4.4, screen 1).
  2. Highlight a3 Focus tracking with lock-on and scroll to the right (figure 4.4, screen 2).
  3. Choose one of the six choices from the menu. Figure 4.4, screen 3, shows 3 (Normal), the factory default of about 1 second. The longest period, 5 (long), seems to provide only about 2 seconds of delay in my experience. Time each of these for yourself and see what you think.
  4. Press the OK button to select the time-out period.

This function allows you to fine-tune how you want Focus tracking with lock-on to work. The camera can ignore an intruding subject for a second or two.

With Single-point AF, the camera will start the lock-on time-out as soon as the single AF point is unable to detect the subject.

With Dynamic-area AF or Auto-area AF and Focus tracking with lock-on enabled, I was amused at how adamant the camera was about staying with the current subject. I'd focus on a map on the wall and then cover most of the focusing points with the user’s manual. As long as I allowed at least one or two AF points to remain uncovered so the camera could see the map, the focus did not switch to the manual. I could just hear the D800 muttering, "Hah, you can't fool me, I can still see a little edge of that map there, so I'm not changing focus!"

Only when I stuck the D800 manual completely in front of the lens, covering all the AF points, did the camera decide to start timing the Focus tracking with lock-on time-out. After a second or two, the camera would give up on the map and focus on the manual instead.

Try this yourself! It's quite fun and will teach you something about the power of your camera's AF system.

Does Lock-On Cause Autofocus to Slow Down?

Some misunderstanding surrounds this technology. Because it is designed to cause the autofocus to hesitate for a variable time period before seeking a new subject, it may make the camera seem sluggish to some users.

But, this "sluggishness" is really a feature designed to keep you from losing your subject's tracked focus. Once the camera locks on to a subject's area of focus, it tries its best to stay with that subject even if it briefly loses the subject. This keeps the lens from racking in and out and searching for a new subject as soon as the previous subject is no longer under an AF point.

It also causes the camera to ignore other higher-contrast or closer subjects while it follows your original subject. You will have to judge the usefulness of this technology for yourself. I suggest that you go to some event or down to the lake and track moving objects with and without lock-on enabled. Your style of photography has a strong bearing on how you'll use—or whether you'll use—Focus tracking with lock-on.

Focus tracking with lock-on has little to do with how well the camera focuses. Instead, it is concerned with what it is focused on. Here are some good reasons to leave Focus tracking with lock-on enabled in your camera.

If Focus tracking with lock-on is set to Off, Dynamic-area AF and Auto-area AF will instantly react to something coming between your subject and the camera. When Focus tracking with lock-on is enabled, the camera will ignore anything that briefly gets between you and your subject. If you turn it off, your camera will happily switch focus to a closer subject even if it only appears in the frame for a moment. A good example of this is when you are tracking a moving subject and just as you are about to snap the picture, a closer or brighter object enters the edge of the frame and is picked up by an outside sensor. The camera may instantly switch focus to the intruding subject.

If you turn off Focus tracking with lock-on, you'll have a camera that doesn't know how to keep its attention on the subject you are trying to photograph if something interferes. When using Dynamic-area AF or Auto-area AF mode, I call turning off Focus tracking with lock-on "focus roulette!"

Configuring Custom setting a3 is not difficult. However, you'll need to decide just how long you want your camera to stay locked on to a subject’s area before it decides that the subject is no longer available when something intrudes.

Settings Recommendation: I leave Focus tracking with lock-on enabled at all times. When I’m tracking a moving subject I don’t want my camera to be distracted by every bright object that gets in between me and the subject. In fact the camera defaults to 3 (normal) from the factory. Nikon gives us variable focus lock time-outs so we can change how long the camera will keep seeking the old subject when we switch to a new one. I suggest you play around with this function until you fully understand how it works. Watch how long the camera stays locked on one subject’s area before an intruding object grabs its attention. The time-out period seems shorter on the D800 than on previous Nikons I’ve worked with. Even the Long setting seems to give me only about 2 seconds of lock-on delay. You will have to decide which delay period is best for you. I choose 5 (Long).

This is one of those functions that people either love or hate. Personally, I find it quite useful for my type of photography. Try it and see what it does for you.


Custom Setting a4 – AF Activation

(User's Manual – Page 283)

AF activation allows you to choose whether you want the Shutter-release button to cause the camera to autofocus. If you leave this setting at the factory default, the AF system will be activated when you press the Shutter-release button halfway down or if you press the AF-ON button. You can also select the setting that allows only the AF-ON button to initiate autofocus and the Shutter-release button will not activate autofocus.

The primary purpose of this function is to allow a very experienced photographer to separate shutter release and autofocus operations. A sports photographer may only want to autofocus the camera when she presses the AF-ON button and not when she presses the Shutter-release button.

Various styles of photography require the photographer to find a good autofocus point with the AF-ON button and then fire many frames with the Shutter-release button with no danger of the camera changing the autofocus during shutter release.


Figure 4.5 - AF Activation Camera Screens.


Here are the steps used to configure AF activation (figure 4.5 above):

Select a Autofocus from the Custom Setting Menu and scroll to the right (figure 4.5, screen 1).

  1. Highlight a4 AF activation and scroll to the right (figure 4.5, screen 2).
  2. Choose one of the two choices from the menu. In figure 4.5, screen 3, Shutter/AF-ON has been selected.
  3. Press the OK button to lock in the setting.

Here’s a description of the two selections:

  • Shutter/AF-ON – Autofocus will be activated if you press the Shutter-release button halfway or if you press the AF-ON button.
  • AF-ON Only – Autofocus works only when you press the AF-ON button. The Shutter-release button will not activate autofocus; it will only start metering and release the shutter.

There are two distinct needs addressed with this function. A few people need to separate autofocus and shutter release. Most don’t. If you prefer to autofocus only with the AF-ON button, you can set it with this function. Otherwise, you’ll autofocus by pressing the Shutter-release button halfway down. If you have Shutter/AF-ON selected, you can autofocus with either button.

Settings Recommendation: I use Shutter/AF-ON myself because I’m primarily a nature shooter and don’t need to separate autofocus from shutter release. I don’t have many fast-moving subjects, other than flying birds or leaping deer. And with those, it just feels more natural to me to autofocus and fire the shutter with one button.

However, if I were shooting a high-speed event and wanted to maximize my camera’s firing speed (frame rate), I wouldn’t hesitate to use AF-ON only, and I would change Custom setting a1 – AF-C priority selection to Release priority. That would let me use my thumb to autofocus with the AF-ON button while my index finger is on the Shutter-release button firing bursts of images—using the Continuous high (CH) frame rate. I would autofocus only when needed and would use depth of field to cover small focus variations. That way, I could get as many pictures into my camera as possible for later publication choices.


Custom Setting a5 – AF Point Illumination

(User's Manual – Page 284)

AF point illumination helps you see the currently active AF points when you first start autofocus. You’ve seen the little squares—representing the active AF point or points—in the Viewfinder, when they briefly appear in red and then turn black. Sometimes the viewfinder is dark, and it might be difficult to see a black square.

If AF point illumination is set to Off, you’ll still have the black square that represents your selected AF point but may not be able to see it. If you set AF point illumination to Auto or On, the point will flash red when you first start autofocus or move the AF point with the Multi selector.

There are three selections on the AF point illumination screen. These affect how the AF points are displayed when active.


Figure 4.6 - Custom Setting a5 - AF Point Illuminations Screens.


First, let’s examine the steps to configure AF point illumination. Then we’ll talk about how the settings work (figure 4.6).

  1. Select a Autofocus from the Custom Setting Menu and scroll to the right (figure 4.6, screen 1).
  2. Highlight a5 AF point illumination and scroll to the right (figure 4.6, screen 2).
  3. Choose one of the three choices from the menu. In figure 4.6, screen 3, Auto has been selected.
  4. Press the OK button to lock in the setting.

Here’s a list of each selection and a description of their functions:

  • Auto – If the Viewfinder’s background is dark, the selected AF point(s) will briefly flash red when you press the Shutter-release button or AF-ON button to start autofocus. If the background is bright, you'll have no trouble seeing your AF point’s little black squares, so they don’t flash red when you start autofocus.
  • On – The selected AF point is highlighted in red when you start autofocus, regardless of the light level of the background.
  • Off – The selected AF point does not light up in red when you start autofocus. It always stays black.

Settings Recommendation: The simplest setting to use is Auto because that lets the camera determine whether there is enough light coming through the Viewfinder for you to see the AF point(s) at the start of autofocus. If you want to force the AF point(s) to flash each time you start autofocus or move the point(s) with the Multi selector, you can set AF point illumination to On. I wouldn’t leave this set to Off unless I was in a consistently lighted studio where the Viewfinder has good contrast.


Custom Setting a6 – Focus Point Wrap-Around

(User's Manual: Page 267; Page 272)

Focus point wrap-around allows you to control how AF point scrolling on the Viewfinder works. When you are scrolling your selected AF point to the right or left, or even up and down in the array of 51 points, it will eventually come to the edge of the Viewfinder area.

This setting allows you to set whether the AF point simply stops when it gets to the edge or scrolls to the opposite side. If you are scrolling the AF point to the left and it reaches the far left side of the screen, it will stop. If Focus point wrap-around is set to Wrap, the point will not stop and instead reappears on the right side of the screen. It "wraps" around. This setting works the same way in an up and down direction. If you scroll off the top of the sensor area, the AF point will reappear on the bottom when Wrap is enabled.



Figure 4.7 - Custom Setting a6 - Focus Point wrap-around.


Here are the steps used to configure Focus point wrap-around (figure 4.7):

  1. Select a Autofocus from the Custom Setting Menu and scroll to the right (figure 4.7, screen 1).
  2. Highlight a6 Focus point wrap-around and scroll to the right (figure 4.7, screen 2).
  3. Choose one of the two choices from the menu. In figure 4.7, screen 3, No wrap has been selected.
  4. Press the OK button to lock in the setting.

Here is a description of the two choices:

  • Wrap – This setting allows the selected AF point to scroll off of the Viewfinder screen and then reappear on the other side.
  • No wrap (default) – If you scroll the AF point to the edge of the screen, it stops there! You'll have to use the Multi selector to move the point in the opposite direction, back toward the middle.

Settings Recommendation: Wrapping the AF point around from one side to the other drives me bonkers. I don’t like it on my computer screen or in my camera’s Viewfinder. When the AF point gets to the edge, I want it to stop so that I can scroll back the other way with the Multi selector. However, I humbly submit that some people will simply adore having their AF point wrap to the other side of the Viewfinder. If that describes you, simply set it to Wrap. It’s always No wrap for me!



Custom Setting a7 – Number of Focus Points

(User's Manual – Page 285)

Number of focus points allows you to adjust the distance the AF point moves when you move it around the screen with the Multi selector.

If you move your AF point often, it might get tiring to scroll through the full 51 focus points, one AF point jump at a time. In older Nikon cameras, we had a maximum of 11 sensors to scroll through, so it wasn't too bad. However, with 51 AF points, it could take longer than you want to scroll from one side of the viewfinder to the other. Or, you might just like the old way better!

Nikon has given you a choice. If you'd rather not scroll through 51 sensors, you can set AF point selection to 11 sensors instead (see figure 4.8A below).


Figure 4.8a - Custom Setting a7 - Number of Focus Points.

In Figure 4.8A (above), the screen on the left shows the 11-point setting, while the right screen shows the 51-point selection.

This does not change the fact that there are 51 sensors available in Dynamic-area AF or Auto-area AF modes. It just means that the Multi selector will make the selected sensor move farther with each press. It skips over sensors when you scroll in Single-area AF and Dynamic-area AF modes. This means that you cannot choose "in-between" sensors as selected AF points, so you have a smaller choice of sensors to start autofocus.

When using Auto-area AF, the camera does not allow you to move the AF points. So this function does not affect the camera when Auto-area AF is selected.

If you are unhappy when scrolling through 51 points, change it to 11. You can always change it back!



Figure 4.8b - Custom Setting a7 - Number of Focus Points Selection Screens


Here are the steps to select one of the AF point selection settings (figure 4.8B above):

  1. Select a Autofocus from the Custom Setting Menu and scroll to the right (figure 4.8B, screen 1).
  2. Highlight a7 Number of focus points and scroll to the right (figure 4.8B, screen 2).
  3. Choose one of the two choices from the menu. In figure 4.8B, screen 3, AF51 51 points has been selected.
  4. Press the OK button to lock in the setting.

Here is a description of each AF point selection selection:

  • 51 points (default) – Choose from any of the 51 focus points (AF points) when you are scrolling through them.
  • 11 points – Choose from only 11 focus points (AF points) when you are scrolling through them. The other AF points are still available for autofocus; you just can't scroll directly to them—some are skipped. That means the Multi selector will move the selected AF point around more quickly.

Settings Recommendation: I usually leave my camera set to 51 points for nature work because I have time to scroll among the AF points in an unhurried fashion. The only time I’ll change that is when I need to shoot very quickly at an event that moves at a rapid pace, like a graduation ceremony or wedding. At these events I may not have time to scroll through all 51 points to select an AF point on the edge of the Viewfinder, so I’ll set AF point selection to 11 points.

Remember, setting it to 11 points does not change how many AF points are actually used by the camera. It only effects how fast you can move among the AF points when you use the Multi selector to scroll around. Some AF points are skipped during scrolling. You still get the benefit of the other 51 points, if they are set to be active.


Custom Setting a8 - Built-In AF-Assist Illuminator

(User's Manual – Page 286)

You've seen the very bright little light on the front of the D800, near the grip (figure 4.9A). Nikon calls this function the Built-in AF-assist illuminator, and it lights up when low-light conditions are sensed and when you’re using certain AF-area modes (not all) to help with autofocus.

Well, this setting allows you to control when that powerful little light comes on.


Figure 4.9a - Built-In AF-Assist Illuminator on Front of Camera




Figure 4.9b - Built-In AF-Assist Illuminator settings screens

We’ll look into the two modes of this setting, but first here are the steps to set the Built-in AF-assist illuminator to On or Off (figure 4.9B):


  1. Select a Autofocus from the Custom Setting Menu and scroll to the right (figure 4.9B, screen 1).
  2. Highlight a8 Built-in AF-assist illuminator and scroll to the right (figure 4.9B, screen 2).
  3. Choose On or Off from the menu. In figure 4.9B, screen 3, On has been selected.
  4. Press the OK button to lock in the setting.

Here are descriptions of how On or Off affects the AF-assist illuminator:

  • On (default) – If the light level is low, the built-in AF-assist illuminator lights up to help light the subject enough for autofocus. This only works in certain modes, though:
  1. Single-servo AF (AF-S) as a Focus mode at any time it's needed
  2. Auto-area AF as an AF-area mode any time it's needed
  3. Single-point AF and Dynamic area AF as an AF-area mode if you are using only the center AF point as the selected sensor
  4. When Continuous-servo AF (AF-C) is selected as a Focus mode, the built-in AF-assist illuminator becomes inactive.
  • Off – The AF-assist illuminator does not light up to help you in low-light autofocus
    situations. The camera may not be able to autofocus in very low light.

Settings Recommendation: I leave Built-in AF-assist illuminator set to On most of the time. It is activated only when the light is low enough to need it. However, let me qualify this for specific circumstances. If you are trying to take pictures without being noticed, such as from across the room with a zoom lens or while doing street photography, you certainly don’t want this extremely bright little light drawing attention when you start autofocus. Or, you may be shooting wildlife, such as a giant grizzly bear, and surely don’t want to call attention to yourself by shining a bright light into the old bear’s eyes. Use this feature when you don’t mind others noticing you—especially if they are 8 feet tall with claws and fangs—because it will draw attention immediately.

Want more info on the great Nikon D800's series?

Forums: More Nikon D850/D810 & D800 reading and discussion in the Forums.

Articles where the Nikon D800 is reviewed or being used

Reviews on the Nikon D810

Articles relating to the Nikon D850


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Post D800 Question

(6 Votes )

Originally written on October 8, 2012

Last updated on January 10, 2021


William Jeffrey Thomas (waj) on February 27, 2015

Excellent article. Concise, comprehensive a great aid to us beginners.

User on February 13, 2013

I agree that a5 should be set to AUTO. However, if you choose an image format different than FX, for ex. x1.2 or x1.5 and want the border to be greyed, you must set a5 to OFF ! Nikon, why is that so ?? It should be two separate settings !

Dr. Patrick Buick (profpb) on January 9, 2013

I've finally learned to use auto Focus using the "AF-ON" button on the back of my D800 instead of pressing the shutter release button half-way. My problem is when using a remote shutter release cable connected to the 10-pin port on the front of my camera body it activates the previously locked auto focus. No, I'm not going to move anything on my tripod set up switching to manual focus. I need help solving this problem from someone thinking more clearly that myself or who can refer me to a written solution.

User on December 11, 2012

I set my AF-C to release priority and AF-S to focus priority. When I'm shooting high(er) speed subjects on AF-C, I often do rely on dof and experience (pre-focusing on the anticipated point of action) to capture the peak and want the camera to fire when I press the release. As Darrell explains, I use the AF-ON exclusively to focus. When I'm shooting subject that aren't moving much, I use AF-S and then the priority is focus. Seems natural that way, although I still use the AF-ON exclusively for focusing.

John M. Cameron (jmcameron) on November 26, 2012

Darrell, Love the book! It is really helping me move deeper into the digital world. It is absolutely amazing the differences between slide/film and digital based photography. Trust you had a very Happy Thanksgiving. Sláinte, John

John Cramer (d3scameraman) on November 18, 2012

Have just recently bought a D800 and have been experimenting with these settings, your explanations here are a huge help, thankyou.

Dr. Patrick Buick (profpb) on November 9, 2012

O.K. I studied this section slowly with my coffee as you suggested. Thank you again, Darrell; I now get it. It is the time before re-focusing. I set mine for long because I must be slow (in learning). So, it was the coffee that made the difference. The book assumumed I was paying attention. My thumb is relieved. With my index finger focusing it got tired holding the button. I am very happy to be learned--finally.

Dr. Patrick Buick (profpb) on November 9, 2012

That's my question too. I have your great D800 book as I do the D7000 book which is the reason I pre-ordered the D800 book. I learned of the AF-ON button from the seven guys sitting at my ANPAT12 dinner last month but the detail was not answered by them or the book. Do I sound impatient? No, I need you, Darrel.

User on October 27, 2012

Darrell, when pressing the AF-ON button, doesonekeep it pressed? Or remove the thumb? Thx