Focus Limiter, Saved Positions and Manual Focus

A feeder hangs 12 m from the hide and the Nikkor 180-600mm zoom is at 600 mm. A blue tit lands, you half-press, and the lens snaps to a hawthorn twig 3 m away. You try again, and the lens runs to its closest distance and back before settling. The bird has gone. The autofocus (AF) searched every distance from 2.4 m to infinity, as asked, twig included.

Firmware 2.00 gave the Z6III a way to rule those distances out. Page numbers in parentheses point to Nikon's Z6III Reference Guide, edition 09, which matches firmware 2.00.

01.Why a Lens Hunts

The Ruler for Focus Is One Over Distance

Take the simplest lens, one thin piece of glass of focal length $f$ with the sensor a fixed distance $v$ behind it. A subject at distance $d$ is sharp when

$$\frac{1}{f} = \frac{1}{d} + \frac{1}{v}.$$

With $v$ fixed, refocusing means changing the lens's power $1/f$ by exactly the change in $1/d$. So the natural ruler for focus is one over distance, in dioptres, where one dioptre is $1\ \text{m}^{-1}$: 4 m sits at $0.25$ and infinity at zero. My lens here is the Nikkor Z 180-600mm f/5.6-6.3 VR, VR (vibration reduction) being Nikon's name for stabilisation.

At 600 mm it focuses as close as 2.4 m, measured from the sensor (lens guide, p. 39). Its range therefore runs from $1/2.4 = 0.417$ dioptres down to $0$. Everything from 8 m to infinity takes up $1/8 = 0.125$ of that, or $0.125/0.417 \approx 30\%$. The other 70% of the range in dioptres lies between 2.4 m and 8 m, where a bird at 12 m cannot be.

A window from 8 m to 20 m spans $1/8 - 1/20 = 0.125 - 0.050 = 0.075$ dioptres, which is $0.075/0.417 \approx 18\%$ of the range. The twig at 3 m sits at $1/3 = 0.333$, far outside it. The 8, 12 and 20 m figures are illustrative, and 2.4 m is Nikon's.

These are shares of the range in dioptres, which a real lens's focus travel follows only roughly. A thin 600 mm lens focused 2.4 m from the sensor would reproduce the subject life size, yet Nikon gives this lens a maximum of $0.25\times$ (lens guide, p. 39), so its optics are far from one thin piece of glass.

The middle bar is the lens's own focus limit switch at its second position, 6 m to infinity. It keeps $1/6 = 0.167$ dioptres, or $0.167/0.417 = 40\%$ of the range at 600 mm, and at 180 mm, where the lens focuses to 1.3 m, it keeps $0.167/0.769 \approx 22\%$, since $1/1.3 = 0.769$. Nikon publishes no figure for how much faster a narrow window focuses, so I give none.

What Hunting Is

The Z6III reads focus from pixels on the sensor, as How Autofocus Works on the Sensor explains. When the area under the focus point is too dark, plain or blurred to read, the camera sweeps the lens looking for a reading, which is called hunting. A limiter shortens the sweep and stops the twig winning, a different job from Subject Detection, which chooses what to follow.

02.The Focus Limiter

Focus limiter setting added in Firmware 2.00 has two parts. Focus limiter turns the rule on or off and is OFF by default (p. 623). Limit range holds Nearest and Farthest, each from 0.1 m to 999 m (p. 648), and a new camera holds no range, shown as a dash in the defaults list (p. 623). When the limiter is on, an icon says so (p. 648) on the monitor and in the electronic viewfinder (EVF), the screen at your eye (pp. 931, 939).

It needs a Z mount lens (p. 648), which probably excludes F mount lenses on the FTZ II or FTZ adapters, though Nikon does not say so outright. Nikon's 2.00 download page also lists eight Nikkor Z lenses that cannot use it, as of November 2025: the DX 16-50mm f/3.5-6.3 VR, DX 18-140mm f/3.5-6.3 VR and DX 50-250mm f/4.5-6.3 VR (DX marks lenses for Nikon's smaller-sensor bodies), and the Z 24-200mm f/4-6.3 VR, Z 24-50mm f/4-6.3, Z 14-24mm f/2.8 S, Z 24-70mm f/4 S and Z 14-30mm f/4 S. My 24-70mm f/4 S is on the list and the 180-600mm is not. With another maker's lens, check that focus really stays inside the window. Auto capture, the 2.00 feature that fires the shutter by itself, cannot run with the limiter on (p. 577).

Setting the Range

Highlight Limit range and press right, and a focus-point target appears (p. 649). For the near limit, put the point on something at that distance and press AF-ON, the rear button that starts autofocus on its own. For the far limit, aim at something at that distance and half-press. The main command dial, or AF-ON held while turning the focus ring, fine-tunes the near value, and the sub-command dial, or a held half-press with the ring, fine-tunes the far one (p. 649). Press OK to finish, or the delete button to clear both values (p. 650).

At the feeder, press AF-ON on a fence post 8 m away and half-press on the hedge at 20 m. The window looks lopsided, 4 m in front of the feeder and 8 m behind, but in dioptres it is nearly centred: $1/8 - 1/12 = 0.042$ in front, $1/12 - 1/20 = 0.033$ behind. Far distances take little of the range, so be generous there.

Range values show in white or yellow. Nikon recommends white, warning that yellow values can weaken the camera's distance judgement, so it may focus outside the window or not at all (p. 649). The guide does not say where yellow begins, so read it with your lens on. I would add a metre of margin at the near end, since the limits are the camera's estimate, not a tape measure.

When the Lens Changes

A range belongs to the lens it was set with. Mount another lens and it stops working until you set a new one, and if you never do, refitting the first lens restores it (p. 650). Nikon's wording implies one stored range at a time.

Lenses With Their Own Limit Switch

The 180-600mm's limit switch has two positions. FULL allows the whole range, given as 1.3 m to infinity, and the other allows only 6 m and beyond, which Nikon suggests for quicker focusing when the subject stays at least that far away (lens guide, p. 13). The switch needs no menu but has two fixed choices and no far limit, while a15 sets both ends on any compatible lens.

So I roam with the switch at 6 m and a15 off, and at a feeder, perch or stage I turn a15 on with the switch at FULL. Menus and Controls sets this lens up with the switch and calls a15 unnecessary there, which is right for roaming. The two chapters agree: the switch for roaming, a15 for a fixed spot.

A Button for the Limiter

The Focus limiter role added in Firmware 2.00 puts it on a custom control: a press toggles Focus limiter, and a hold opens Limit range (p. 705). The video controls offer the same role for the same a15 (p. 750), so photo and video share one limiter. Menus and Controls covers assigning roles.

03.Saved Positions

Save Focus Position

Save focus position is OFF by default (p. 806). With ON, the camera restores at switch-on the focus it had at switch-off, perhaps starting more slowly (p. 828). Temperature, zoom or other changes can still move focus, and even at OFF focus can come back to where it was, depending on the body and lens (p. 828). I would use it for a night sky focused by hand, checking focus after each start because the air cools, and otherwise leave it OFF.

Recalling Focus From a Button

Among the custom controls, assign Recall focus position to one or more controls and Save focus position to another (pp. 718-721). Focus, hold the save control, and a recall control then drives focus straight back there. Save to all stores one distance for every recall control, and Save individually gives each its own. Saving works in any focus mode but not with shooting information displayed, and the distance is lost when the lens comes off, while temperature or zoom changes can shift a recall (p. 718). Holding a recall control puts the camera in manual focus (MF), and a half-press will not refocus (pp. 719, 721). Lenses with a memory set button and function ring come with these roles assigned (p. 626).

On stage I would save a dancer's opening mark, and with the 180-600mm a favourite perch.

Save Zoom Position (PZ Lenses)

A power zoom (PZ) lens zooms by motor. Save zoom position (PZ lenses) is OFF by default (p. 806), and with ON and a PZ lens fitted, the camera restores the zoom setting at switch-on (p. 829). No lens is named there, and the one in neighbouring compatibility notes is the Nikkor Z 28-135mm f/4 PZ (pp. 722, 738), not necessarily a full list. The Save and load power zoom position role stores the zoom on a hold and recalls it on a tap (p. 705), one position for photo and video that survives switching off but not a lens change (p. 722). I have no PZ lens, so it stays OFF.

04.Focusing by Hand

Manual Focus on the Z6III

In MF you turn a ring and the camera does not refocus. Choose it with the camera's focus mode, covered in Focus Modes, or a lens switch where one exists (p. 137). On the 180-600mm, MF chosen on the camera overrides the lens's A/M switch (lens guide, p. 13), and its control ring does the focusing (p. 136, lens guide p. 8).

The zoom-in button magnifies the view (p. 136), to about $24\times$ in photo mode, with zoom-out to return and the multi selector to scroll (p. 106). In video the steps are 50%, 100% (one image pixel per screen pixel), 200% and 400%, though 50% is missing at the $1920 \times 1080$ frame size and zoom is unavailable while recording RAW video (p. 110). The two scales differ: $24\times$ compares the view with the whole frame, while a percentage counts screen pixels per image pixel. Firmware 2.00 raised the top step from 200% to 400%, and Nikon's download page says that applies in both modes.

The focus indicator, which Nikon calls electronic rangefinding, shows whether focus under the point is on the subject, in front or behind, and flashes when the camera cannot tell (pp. 136-137), and the point turns green when sharp (p. 136). On subjects autofocus struggles with it can claim focus falsely, so magnify and check, and it may flicker near the frame edge (p. 137). A distance indicator shows where focus is set (p. 136), counted from the focal plane mark on the body, 16 mm behind the lens mount flange (p. 137).

Focus Peaking

Picture pixels crossing the edge of a dark feather against pale sky, brightness on a scale of 0 to 255. Sharp, the row reads 20, 20, 200, 200, a jump of 180 between neighbours. Defocused, the same rise spreads out as 20, 65, 110, 155, 200, and the largest neighbour step is 45. Defocus keeps the total change and removes the steepness.

Peaking measures something like that step across the frame and paints pixels where it passes a threshold. At 100, only the sharp edge is painted. At 40, the soft edge is painted too, so a deeper slice looks sharp. The numbers are illustrative and Nikon does not publish its method, so this is the general principle, not the Z6III's algorithm. It explains why a grey heron on grey water may get little paint even when sharp.

Focus peaking display turns it on and is OFF by default (p. 623). Focus peaking sensitivity runs from 1 (low sensitivity) through 2 (standard), the default (p. 623), to 3 (high sensitivity), and Nikon's description fits the threshold idea: a higher number shows more depth as sharp (p. 645). Focus peaking highlight color is Red by default (p. 623), and the guide says it can be changed without listing the choices. Peaking works in manual focus (p. 645) and may not appear if the camera finds no outlines (p. 137).

Photo and video share a12, which can be added to the i menu, the quick menu on the i button, in both modes (pp. 701, 746), though neither default i menu includes it (pp. 625, 627). A control can take the Focus peaking display role (pp. 711, 752), and with zebra stripes also on in MF, only peaking shows (p. 773).

I use ON at 2 (standard), since by Nikon's description 3 marks a deeper zone, which hides the sharpest plane. I keep Red unless the scene is red, as under red stage light, and then pick a colour the scene lacks.

Manual Focus Ring in AF Mode

Manual focus ring in AF mode is ON by default (p. 623), for compatible lenses only (p. 651), which Nikon does not list. With ON, turning the focus ring during a half-press overrides autofocus, and releasing and half-pressing again refocuses. With OFF, the ring cannot focus in AF (p. 651). Nikon calls the first autofocus with manual override.

The 180-600mm has no separate focus ring. Its control ring focuses in MF and does whatever the camera assigns in AF (lens guide, p. 8), and the Focus (M/A) role gives manual override through it (p. 714). Reading the two manuals together, the override on this lens comes from that role, not a16. Back-Button Focus covers override with AF-ON.

I leave a16 ON and put Focus (M/A) on the 180-600mm's control ring. The cost is that on a wide focus ring, like that of the Tamron 70-180mm f/2.8 Di III VC VXD G2, a resting hand can shift focus during a half-press. Nikon does not say whether a16 governs that Tamron, so test it on the body.

Half-Press to Cancel Zoom

Half-press to cancel zoom (MF) added in Firmware 2.00 is OFF by default (p. 625). With ON, a half-press returns a magnified MF view to the full frame (p. 685). Video has its own copy, g18 (p. 778), covered in the video part. I set it ON: magnify, focus, half-press, recompose and shoot, without reaching for zoom-out.

Reverse Ring for Focus

Reverse ring for focus is OFF by default (p. 627). With ON, turning the focus or control ring moves focus the opposite way on Z mount lenses in MF, except certain manual-only Z lenses and F mount lenses on the FTZ II or FTZ (p. 736). My lenses all agree, so it stays OFF.

Focus Ring Rotation Range

A ring whose effect depends on turning speed cannot be geared to the glass, so it must be a sensor driving a motor, called focus by wire. That is my inference, not Nikon's statement.

Focus ring rotation range defaults to Non-linear (p. 627) and offers Non-linear, a fixed angle from 90° to 720°, and Max. (p. 737). Non-linear moves focus far on a fast turn and little on a slow one, whatever the angle. A fixed angle is the turn that carries focus from minimum distance to infinity, larger for finer control, and Max. is the largest the lens allows at its current settings. A lens without support stays at Non-linear (p. 737).

In numbers, if angle $R$ covers the full travel, a turn of $\theta$ moves focus $\theta/R$ of the way. With $R = 90^\circ$, a $45^\circ$ turn moves it $45/90 = 1/2$ of the way, and with $R = 720^\circ$ the same turn moves $45/720 = 1/16$. Non-linear has no formula: a quick $45^\circ$ leaps, a slow one creeps, so a mark on the ring never lands twice at the same distance.

Non-linear suits stills. Linear suits a video focus pull, a planned shift of focus during a shot, which needs the same turn on every take. Nikon does not list which lenses accept a fixed angle, the Nikkor Z 85mm f/1.8 S needed lens firmware first (see Firmware and Updating), and the guide does not say whether f9 and f10 act while filming. I keep Non-linear and would test a fixed angle in video mode before gimbal work.

05.Adapted Manual Lenses

What a CPU Lens Tells the Camera

A Nikkor Z lens has electrical contacts that carry data to and from the camera (180-600mm lens guide, p. 10). Nikon calls these CPU lenses, after the central processing unit, the chip doing the talking. An old manual lens on an adapter has none, so the camera learns nothing. The lens warning appears, and Nikon says no action is needed (p. 923).

Stabilisation needs the focal length. A small tilt shifts the image by roughly focal length times the angle in radians. For an illustrative $0.001$ radians, about $0.06^\circ$, the shift is $50 \times 0.001 = 0.05$ mm at 50 mm and $400 \times 0.001 = 0.4$ mm at 400 mm. A stabiliser that moves the sensor must know which to correct, as Vibration Reduction explains.

Non-CPU Lens Data

Non-CPU lens data is for chipless lenses on an adapter, and entering focal length and maximum aperture opens some CPU-lens features to them, on-board vibration reduction among them (p. 826). Lens number selects the stored entry, 1 by default (p. 806). Focal length (mm) and Maximum aperture start blank (p. 806). Lens name, which arrived with firmware 2.00 for lens numbers 1 to 20, takes up to 36 characters (p. 826) and starts blank (p. 806), and is written into the Exif data (p. 826), the Exchangeable Image File Format record stored in each picture. The page does not say whether focal length and aperture reach Exif too, so check a picture's information before relying on them. The Choose non-CPU lens number role switches entries from a control (p. 714).

I would always enter a name, since it is the one field promised to reach the file. For a manual zoom one stored focal length cannot follow the ring, so enter the one you use most.

Distance Units

Distance units shows the MF focus distance in Meters (m), the default (p. 806), or Feet (ft) (p. 827), and Nikon calls that distance a guide that varies with the lens (p. 827). Auto capture's distances stay in metres whatever you choose (p. 576). The guide gives a15's range only in metres (p. 648) and does not say whether its display follows this setting, so I keep Meters (m).

06.Recommended Settings

For stage dance with the Tamron, a window from the stage front to the back wall keeps focus off the heads in front, if the lens honours it: from a seat 12 m back with a stage 10 m deep, both illustrative, that is 12 m to 22 m, or 11 m to 23 m with a metre of margin at each end. For landscape I use AF-S by day and MF with peaking and d19 at night. For street the limiter stays off.

07.Beginner Mistakes

Leaving the limiter on after the feeder. A bird at 5 m will then be ignored. Watch for the icon, and put the role on a control.

Setting a range with the lens switch at 6 m. Nikon asks for FULL with Limit range (p. 650). Check the barrel first.

Expecting a range to follow a lens change. It stays with the lens it was set on (p. 650). Set it again.

Swapping adapted lenses without changing the lens number. A 135mm lens on a 50mm entry is stabilised for the wrong focal length.

08.Related Chapters

• How Autofocus Works on the Sensor: what the camera measures, and why it hunts.
• Focus Modes: single, continuous and manual focus.
• Subject Detection: what the camera follows.
• Back-Button Focus: autofocus from AF-ON.
• The Focus Custom Settings: the other autofocus custom settings.
• Choosing an Autofocus Setup: where the limiter fits in a full setup.
• Vibration Reduction: the stabiliser that non-CPU lens data feeds.
• Firmware and Updating: lens firmware, including the 85mm update.
• Firmware History: what version 2.00 added.
• Glossary: short definitions.