SteveDickinson
Nikon D850 – Focus

Focus modes

The D850 provides three focus modes:

  • Manual
  • Single
  • Continuous

Manual mode is selected by setting the focus switch on the front left of the camera next to the lens to M. If the lens is equiped with a M/A M switch, then this should also be set to M.

The other two modes are selected by pressing the button in the middle of the Focus Selector switch and then using the Main Dial to select:

  • AF-S – Single
  • AF-C – Continuous

Manual Focus mode

Manual focus mode does what is says on the tin. It is your job to set the focus. The D850 will still provide assistance in setting the correct focus by indicating when the subject in the focus area is in focus. Depress the shutter release button half way, and in the viewfinder the Focus indicator circle will appear solid when the subject is in focus. The arrows either side will indicate whether the subject is in front of, or behind the focal plane. Note: There is no equivalent indicator in Live View mode.

AF-S Single Mode

In Single mode, depress the shutter release button half-way and the D850 will focus on the subject in the Focus Area once, and will lock the focus, so if either the subject or you move the focus will not change. AF-S is therefore best for stationary subjects, such as landscapes or portraits of people.

With AF-S selected you have three options as to the Focus Area

  • S – Single Point
  • Grp – Group
  • Auto

Single point will display a single box that you can move using the cursor button on the rear of the D850.

GRP will display a Group of points, which again you can move around using the cursor button. In this case the D850 will choose the focus that brings most of the subjects in the group area into focus.

Auto – It is out of your hands. The D850 will analyze the image and decide what are the subjects of interest and set the focus on them. The D850 is very good at facial detection and will give priority to people in the scene. However it is worth noting that priority is given to objects nearer the front than the rear.

AF-C Continuous

In continuous mode the D850 will, when the shutter release button is depressed halfway, focus on the subject in the Focus Box, but will then track that subject should it or you move. Note: This mode will use more power than AF-S mode, but if your subjects are not stationary, then AF-C is the way to go.

The area of search that the D850 uses when having to refocus is up to you. You have eight different selection modes to choose from

  • S – Single
  • 9-Point Dynamic
  • 25-Point Dynamic
  • 72-Point Dynamic
  • 153-Point Dynamic
  • 3D
  • Group
  • Auto

S – Single

A single focus box is displayed in the view finder/rear screen. The box can be moved using the joystick or the multi-selector dial. This method is good for selecting a specific, stationary target, especially for portraits.

9/25/72/153-Point Dynamic

With all of these modes, you select the initial target, and the D850 will focus on the selected target. However if you or the target moves, the D850 will examine the surrounding 9, 25, 72 or 153 focus points to re-evaluate the focus.

9-Point – Use when you are expecting the subject to remain reasonably stationary.

25-Point – Use when you are expecting the subject to move slowly and predictably. Say a rowing boat or river punt.

72-Point – Use on large subjects that move erratically. Be aware though that the D850 is inspecting a large area in order to refocus, and if the subject is not the primary object in the scene, the camera my focus on the background.

153-Point – Use on large fast moving objects. As with 72-Point Dynamic, if your subject is not the principle object in the view, the D850 may well focus on the background or another object.

3D

As with 153-Point dynamic you select the initial focus subject, but should you or the subject move the D850 will use distance information to plot the movement of the subject and keep it in focus. Custom settings allow you to turn on/off facial recognition and to decide on the width of the tracking search. Nikon recommends this setting for subjects that move erratically – like a child at play, or player in a team sports game.

Group – GRP

GRP will display a Group of points in a Cross shape, which again you can move around using the cursor button. In this case the D850 will choose the focus that brings most of the subjects in the group area into focus. Faces that are detected (if you have switched on Face Detection) will take priority.

Some professional photographers recommend this setting for taking pictures of birds in flight, as you can focus on an area where you anticipate the bird will appear and if you have the correct general area the D850 will focus on the bird when it appears.

Auto

It is out of your hands. The D850 will analyze the image and decide what are the subjects of interest and set the focus on them. The D850 is very good at facial detection and will give priority to people in the scene. However it is worth noting that priority is given to objects nearer the front than the rear. Nikon recommend this setting for capturing birds in flight, though note the comment above about GRP setting.

Trap

Trap (Auto) Focus is a neat little trick for ensuring that you capture the perfect action shot, when you know in advance where the action is going to take place, but not exactly when. What you do is set-up the D850 so that it is focused on the point where the action is going to take place, and then set Focus Priority on the shutter so the image will not be captured until something moves into focus in the area you are pointing at.

Obviously there must not be anything in focus there at the time of set-up, or the image will just take, but, assuming that is feasible, then here is how you set up Trap Auto Focus

  • Ensure AF-ON button has not been re-assigned. (Custom Settings f1)
  • Adjust Custom Setting a8 to AF-ON Only – this will stop the AF being triggered by pressing the shutter release half-way.
  • Set Custom Setting a2 to Focus Priority – Prevents an image being taken unless Focus has been established.
  • Set Focus Selection to AF-S Single
  • Ensure Camera and Lens are set to AutoFocus

You the need to focus on the point in question, or an equivalent distance elsewhere, using the AF-ON button. Re-frame, if necessary, and then press the shutter release all the way just before the action will take place. When the subject moves into focus the image will automatically take.

A couple of points to note though:

  • If there is something already at the focus point, then obviously the image will take immediately
  • If you have a small aperture, then you will have a greater depth of field, and not all the subject maybe in focus when the image takes.
  • Remember to reset a8 afterwards to allow AF when the shutter is depressed half-way.