Dance Video on a Gimbal

The dress rehearsal starts at four in the afternoon, the day before the recital. The director has agreed to one camera in the side aisle, so I walk it with the Z6III on the DJI RS 5 and the Neewer F700 monitor mounted where the motors cannot move it. Twelve dancers run the whole programme under the real show lights, and nobody will stop a piece for me.

Left at its defaults, the camera would spoil the footage in three ways before the first piece ends. Auto ISO would brighten a slow fade that the lighting designer wants dark. Focus would jump to whichever dancer stands nearest the lens when the line breaks up. And a camera left to pick its own shutter speed on a bright cue would turn a spin into a run of sharp, jerky stills.

Each of those has an answer that an earlier chapter already settled. This chapter takes them in the order you meet them on the night, works through the arithmetic behind the shutter and the card, and ends with one card of settings and one button map.

Page numbers in parentheses point to Nikon's Z6III Reference Guide, edition 09, which matches firmware 2.00.

01.The Rig and the Room

A gimbal is a handle with three motors that keep the camera level and pointed where you aim while your arms and feet move beneath it. It turns the shake of walking into a slow glide, which suits dance, where the camera travels with the dancers along the edge of the stage. The motors need a balanced load, and the Z6III alone weighs about 760 g with battery and card (p. 1008). The payload sums for camera and monitor are in HDMI and External Monitors, which mounts the monitor where the motors do not carry it.

For a recital I put the Tamron 28-75mm f/2.8 Di III VXD G2 on the gimbal. From the side aisle the short end takes in a line of dancers and the long end fills the frame with a soloist, so I never change lenses in the dark. That choice is my judgement, and nothing below depends on it.

The F700 gives a large picture you can judge focus on, where the camera's own screen is small and often at an awkward angle on a gimbal. It takes its picture over HDMI, and the monitor chapter sets the feed at 1080p (progressive) with Output shooting info at OFF, so it shows a clean frame. Anchor the cable with a slack loop so it cannot drag on an axis as the motors turn.

One timer can darken that feed while you wait for a piece to start. Nikon notes that when the standby timer runs out, the camera display turns off and HDMI output ends with it (p. 308).

Set its Standby timer to No limit. Longer delays cost battery life (p. 661), and that is a price worth paying when the alternative is a dark monitor as the lights come up on the next piece.

02.Frame Rate and File

The file type decides how the camera squeezes each frame into a file, a method called a codec. Video Formats and Codecs settles on H.265 10-bit (MOV). The "10-bit" means each colour channel is stored in $2^{10} = 1024$ steps of brightness rather than the $2^{8} = 256$ of an 8-bit file, which keeps a slow fade on a dark stage smooth instead of stepped. Highlight that file type and press right to choose its tone mode (p. 199). Choose SDR, standard dynamic range, which records in the BT.709 colour standard of ordinary high-definition video (p. 199).

SDR has a second reason here. Nikon warns that subject detection may work less well when HLG or N-Log is used with H.265 10-bit (p. 130), and a dance film depends on the camera finding people. N-Log, HLG and Exposure Tools explains when the flat N-Log recording is worth that cost, and a recital under designed stage light is not one of those times.

Choose 3840 by 2160 at 30p. Nikon's 30p actually runs at 29.97 frames per second, and its 60p at 59.94 (p. 202). Switch to 60p for a passage you may want to slow down later, such as a leap, because twice as many frames give an editor something to stretch.

Leave Choose image area at FX, which uses a strip of the sensor about 35.9 by 20.2 mm, while DX uses about 23.7 by 13.3 mm (p. 211). DX therefore narrows the view by about 1.5 times and buys reach from the back of the hall. The image area cannot change while a clip records (p. 755), so Image Area and Crop suggests FX for wide shots and switching between takes with a spare button set to Switch FX/DX. The Release mode/protect button does nothing in video by default (p. 627) and could take that role, where offered (p. 749). I leave it out of the map, as Custom Controls does.

Set Destination to CFexpress/XQD card slot, as Cards and Data Rates for Video recommends. That chapter does the card arithmetic in full, and a recital with a slowed passage is a good test of it.

Suppose the evening needs 90 minutes at 30p and 30 minutes at 60p. Nikon rates H.265 10-bit at 3840 by 2160 at about 190 megabits per second (Mbps) at 30p and about 340 Mbps at 60p (p. 207). A megabit is an eighth of a megabyte (MB), and a minute has 60 seconds, so each rate becomes megabytes a minute by multiplying by $60/8$.

$$\frac{190 \times 60}{8} = 1425 \text{ MB per minute}, \qquad \frac{340 \times 60}{8} = 2550 \text{ MB per minute}$$

Write $t_{30}$ and $t_{60}$ for the minutes recorded at each rate, and $S$ for the total in gigabytes (GB), taking 1,000 MB to the GB as card labels do.

$$S = 1.425\,t_{30} + 2.55\,t_{60} = 1.425 \times 90 + 2.55 \times 30 = 128.25 + 76.5 = 204.75 \text{ GB}$$

The 512 GB Lexar in slot 1 holds that with $512 - 204.75 = 307.25$ GB to spare by the label. The slowed passage costs nearly as much card as an hour of the rest, which is why 60p is for the leaps and not the whole show.

03.The Shutter Speed Rule

Picture a dancer's hand sweeping through a turn at about 3 m/s. That speed is an assumption for illustration, a brisk arm movement, and not a measurement. At 30p the camera takes a frame every $1/29.97 \approx 0.0334$ s, or 33.4 ms, so between one frame and the next the hand travels about

$$d = v \times \frac{1}{29.97} = 3 \times 0.0334 \approx 0.10 \text{ m}$$

where $d$ is the distance in metres and $v$ the speed in metres per second. Each frame also smears the hand by however far it moves while the shutter is open. The smear is $b = v\,t$, where $t$ is the shutter speed in seconds.

$$b_{1/1000} = 3 \times \frac{1}{1000} = 0.003 \text{ m}, \qquad b_{1/60} = 3 \times \frac{1}{60} = 0.05 \text{ m}$$

At 1/1000 s each frame shows a crisp hand with 3 mm of blur, and the next frame shows it crisp again 10 cm further on. The eye sees a hand that teleports, which is the jerky look from the opening. At 1/60 s each frame smears the hand across 5 cm, half the gap between frames, and the eye joins the smears into one flowing movement.

That half-the-gap habit is what filmmakers call the 180-degree shutter. The name comes from film cameras, whose shutter was a spinning disc with a slice cut away, and the angle $\theta$ of the slice set how long each frame was exposed. For a frame rate $f$ in frames per second and a shutter speed $t$ in seconds,

$$\theta = 360^\circ \times f \times t, \qquad 360^\circ \times 29.97 \times \frac{1}{60} \approx 179.8^\circ$$

so 1/60 s at 30p sits a hair under 180 degrees. Video from First Principles sets 1/60 s for 24p and 30p and 1/125 s for 60p, and the table puts the two numbers side by side.

The camera can show the setting as an angle directly. Custom Setting g12 offers Shutter speed or Shutter angle, and the angle mode runs from 5.6 to 360 degrees (p. 770). Keep Shutter speed, because choosing Shutter angle disables high-frequency flicker reduction and g11 Extended shutter speeds (S/M) (p. 770), and the first of those is the stage-light remedy you may need.

Stage lamps are the other reason for 1/60 s. On 60 Hz mains many lamps pulse 120 times a second, and Shutter Types, Rolling Shutter and Flicker shows why a shutter open for whole pulses avoids banding. At 1/60 s the shutter catches $120 \times 1/60 = 2$ whole pulses in every frame.

Set Frequency to the local mains, 60 Hz in North America. Nikon's own list of speeds for 60 Hz lighting in video is 1/125, 1/60 and 1/30 s (p. 600), which covers both choices in the table. If LED stage lights still draw bands across the frame, High-frequency flicker reduction splits the range from 1/30 s up to 1/8000 s into smaller steps in modes S and M (p. 602), so you can nudge the shutter while watching the stripes on the F700.

04.Exposure in Mode M

Mode M fixes everything you do not touch. Aperture, shutter speed and ISO can all be changed while filming (p. 209), and nothing changes unless you change it. The shutter is already settled. The aperture follows from how much of the stage you want sharp. ISO, the camera's brightness gain, sets what is left.

On stage, set Auto ISO control (mode M) to OFF and choose one ISO during the dress rehearsal, as ISO and Auto ISO recommends. A performance is lit to have bright moments and dark ones, and Auto ISO would fight the lighting designer, lifting a blackout and pulling down a white costume. With Auto ISO off, exposure compensation in M only moves the exposure indicator, the scale that shows how far your exposure sits from the meter's reading (p. 152). It does not darken the clip.

Video offers no spot metering (pp. 212, 603). On stage, Highlight-weighted metering gives the greatest weight to highlights, and Nikon suggests it for spotlit performers (p. 487). In M with a fixed ISO the meter only drives the exposure indicator (p. 152), so it tells you whether the lit faces and costumes, the parts that would clip, sit where you want them. N-Log, HLG and Exposure Tools adds two displays that judge exposure better than any meter. The zebra pattern, Custom Setting g14, stripes a chosen tone range in video mode (p. 772), and that chapter sets Highlights at a threshold of 250, so stripes mark the costume about to lose detail. The wave-form monitor, chosen at g17 (p. 776), plots brightness across the frame from left to right, so a spotlit soloist shows as a tall spike over a dark floor.

Outdoors in daylight the light is not part of the show, and four things change. Turn Auto ISO control (mode M) to ON, and Maximum sensitivity caps how far it may climb (p. 588). Switch to Matrix metering, as Metering recommends for gimbal dance outdoors, and use the ND filter that Video from First Principles recommends to hold 1/60 s in sun. Before the gimbal swings past a bright sky, press the sub-selector centre, which the map below sets to AE lock (hold) where offered (p. 749). It locks on one press, releases on a second press or when the standby timer runs out, and holds when recording starts (p. 751).

The map below puts Power aperture (open) on Fn1 and Power aperture (close) on Fn2, a pair assigned together (p. 753). Power aperture works only in modes A and M, and the display may flicker while it runs (p. 756). The camera may record the sound of the aperture moving (p. 109), and the picture may flicker as it changes (p. 110). Use it between phrases, when a small exposure shift will not show, and never in the middle of a turn.

Out of the box Fn1 carries White balance (p. 627), so holding it and turning a dial changes white balance mid-clip (p. 213). Power aperture takes that button here, which suits a recital. White Balance gives video its own fixed value, a colour temperature or a preset measured at the rehearsal, so colour cannot drift when the light changes on purpose. Any choice other than Same as photo settings in the video menu does that (p. 589).

05.Focus That Follows Dancers

Full-time AF, a video-only mode, keeps focusing with no button held, and a half-press of the shutter-release button locks it (p. 121). That suits a gimbal, where your hands are on the handle and not on the camera.

Wide-area AF (L) gives smooth focus when the camera pans, tilts or follows moving subjects (p. 124). It has a habit you must plan for. When the area holds subjects at different distances, the camera gives priority to the closest one (p. 124). In a group piece, the dancer nearest the lens wins, so frame the dancer you want nearest or move the area over them.

Set Subject detection to People and AF when subject not detected to OFF. With that second setting off, the camera stops focusing when it finds no subject (p. 606), so an empty stage between entrances does not send focus hunting onto the backdrop. Video Autofocus and Stabilisation recommends both.

Leave AF speed at 0 and set When to apply to Only while recording. The camera then uses the chosen speed during a clip and focuses as fast as it can otherwise (p. 760). Faster settings make more lens noise, especially at +5 (p. 760), and a slow, gentle pull between dancers looks deliberate on screen.

AF tracking sensitivity runs from 1, which shifts quickly to a new subject, to 7, which holds the original one (p. 761). The earlier chapter sets 5 when several dancers cross the frame and 4 for a solo, so focus does not leave the dancer you chose each time another passes in front.

For a solo, switch to Subject-tracking AF. Put the focus point on the dancer and press AF-ON to start tracking, then OK to end it and return the point to the centre (p. 125). Both buttons keep their default roles in the map for this. DJI's compatibility page for the RS 5 with a Z6III lists starting and stopping recording over both the USB-C control cable and Bluetooth, but no autofocus trigger over either, so the gimbal cannot start focus. Under Full-time AF the camera focuses by itself anyway. DJI tested with camera firmware 1.00.

06.Electronic VR Against the Gimbal

Electronic VR steadies the picture in software, by recording a smaller area of the sensor and shifting that area against the shake, and Nikon confirms that it shrinks the recorded area (p. 211). On a gimbal the motors already do that job, so the software only takes away field of view. It also caps the ISO at 51200 (p. 209), and it is forced OFF with the RAW file types, the 5376 by 3024 frame size, frame rates of 100p and above, slow motion, Hi-Res Zoom and auto capture (p. 609). Set it to OFF. Video Autofocus and Stabilisation works out how much frame it costs.

Nikon's page for the video Vibration reduction item names only Same as photo settings, the default, which makes video follow the photo menu (pp. 579, 608), though p. 861 says its options vary with the lens. Leave it there, as that chapter does.

What the gimbal cannot fix is rolling shutter. The sensor reads out line by line, as Shutter Types, Rolling Shutter and Flicker explains, and Nikon warns that a horizontal pan can distort the whole frame (p. 110). Pan as slowly as the dance allows, and let the motors smooth the start and the end of each move.

07.Sound and Timecode

The built-in microphone hears the camera. Nikon notes that the sounds of autofocus, vibration reduction and power aperture may be recorded (p. 109), and every one of those runs in this recipe. Use the external microphone route in Audio and Timecode, which sets Audio input selection to External mic (p. 610).

Set Audio input sensitivity to Manual and low. The manual range runs from 1 to 20, and a level meter that turns red means too loud (p. 611). Recital music swings from quiet passages to sudden swells, so set it during the loudest piece at the rehearsal. Frequency response stays at Wide range for music (p. 613). Wind noise reduction acts only on the built-in microphone (p. 614), so it stays OFF. Mic jack plug-in power is OFF for a microphone that powers itself (p. 615), and the audio chapter says to check the level afterwards.

A timecode is a running clock written into every frame, counting hours, minutes, seconds and frames, so an editor can line up two cameras or a separate sound recorder. One camera with sound recorded in it has nothing to line up, so the audio chapter leaves Record timecodes at Off. Leave Drop frame at its default ON (p. 579), which corrects the clock at the 30p and 60p rates (p. 617). H.264 8-bit (MP4) files carry no timecode at all (p. 617).

08.Heat, Batteries and Clip Length

Heat, Power and Recording Limits covers a long event in full, and this recipe follows it. A single clip can run up to 125 minutes (p. 212), and heat can end it sooner (p. 1017). One EN-EL15c gives about 100 minutes of video (p. 1016), less with Wi-Fi and Bluetooth running (p. 1016).

Auto temperature cutout at High gives more recording time, and Nikon warns that the body may grow hot to the touch, so it suggests a tripod or similar support that keeps your hands off it (p. 830). A gimbal does that, since your hands stay on its handle. Airplane mode at ON turns off Bluetooth, Wi-Fi and the ML-L7 remote link (p. 872). DJI pairs the RS 5's Bluetooth shutter through the camera's Wireless remote (ML-L7) setting, so with Airplane mode on, use the RS 5's USB-C control cable or the camera's own record button. Stop and restart between pieces, and swap batteries at the interval, as that chapter sets out.

09.The Recipe

The card gathers every setting above, grouped in the order you would check them in the aisle before the house opens.

Field recipe · Dance video

Dance Video on a Gimbal

Exposure

Setting	Set it to	Why
Mode dial	M	Nothing changes unless you change it
Shutter speed	1/60 s at 30p, 1/125 s at 60p	Close to a 180-degree shutter and on Nikon's 60 Hz list
Shutter modeCustom settings menu > g Video > g12 Shutter mode	Shutter speed	Shutter angle would switch off high-frequency flicker reduction
Auto ISO control (mode M)Video recording menu > ISO sensitivity settings > Auto ISO control (mode M)	OFF	Stage light dims on purpose, so ISO stays fixed until you film outdoors
ISO sensitivity (mode M)Video recording menu > ISO sensitivity settings > ISO sensitivity (mode M)	Set at the dress rehearsal	One value per venue, judged with zebras and the wave-form monitor
MeteringVideo recording menu > Metering	Highlight-weighted metering	Indicator reads the lit costumes on stage, Matrix outdoors
FrequencyVideo recording menu > Video flicker reduction > Frequency	60 Hz	Matches North American mains, so use 50 Hz where the mains run at 50
Pattern tone rangeCustom settings menu > g Video > g14 Zebra pattern > Pattern tone range	Highlights	Stripes mark the costume that is about to lose detail

Format and Colour

Setting	Set it to	Why
Video file typeVideo recording menu > Video file type	H.265 10-bit (MOV)	Smooth fades, and it carries timecode where MP4 does not
Tone mode	SDR	Keeps subject detection at full strength and needs no grade
Frame size/frame rateVideo recording menu > Frame size/frame rate	3840×2160; 30p	The everyday rate, with 60p for a leap you may slow down
Choose image areaVideo recording menu > Image area > Choose image area	FX	The widest view from the aisle, and it cannot change mid-clip
DestinationVideo recording menu > Destination	CFexpress/XQD card slot	The 512 GB card holds the whole evening with room to spare
White balanceVideo recording menu > White balance	Choose color temperature, set at the rehearsal	Colour holds when the lighting changes on purpose

Focus and Stabilisation

Setting	Set it to	Why
Focus modeVideo recording menu > Focus mode	Full-time AF	Focuses through the whole clip with no button held
AF-area modeVideo recording menu > AF-area mode	Wide-area AF (L)	Smooth on moving dancers, with Subject-tracking AF for a solo
Subject detectionVideo recording menu > AF/MF subject detection options > Subject detection	People	Finds dancers rather than scenery
AF when subject not detectedVideo recording menu > AF/MF subject detection options > AF when subject not detected	OFF	An empty stage does not send focus to the backdrop
AF speedCustom settings menu > g Video > g5 AF speed > AF speed	0	A gentle pull between dancers, with less lens noise
When to applyCustom settings menu > g Video > g5 AF speed > When to apply	Only while recording	The set speed during a clip and full speed between clips
AF tracking sensitivityCustom settings menu > g Video > g6 AF tracking sensitivity	5	Holds the chosen dancer as others cross, or 4 for a solo
Electronic VRVideo recording menu > Electronic VR	OFF	The gimbal already steadies the shot, and this one crops the frame

Sound and Timecode

Setting	Set it to	Why
Audio input selectionVideo recording menu > Audio input selection	External mic	The built-in microphone hears the focus motor and the aperture
Audio input sensitivityVideo recording menu > Audio input sensitivity	Manual, low	Set during the loudest piece so a swell never turns the meter red
Mic jack plug-in powerVideo recording menu > Mic jack plug-in power	OFF	The external microphone powers itself, so check the level after
Record timecodesVideo recording menu > Timecode > Record timecodes	Off	One camera with sound in camera has nothing to line up

Power and Monitor

Setting	Set it to	Why
Auto temperature cutoutSetup menu > Auto temperature cutout	High	More recording time, and the gimbal holds the warm camera
Standby timerCustom settings menu > c Timers/AE lock > c3 Power off delay > Standby timer	No limit	Keeps the F700 lit and AE lock (hold) set while you wait between pieces
Airplane modeNetwork menu > Airplane mode	ON	Saves battery. Start clips by USB-C cable or the record button
Output resolutionSetup menu > HDMI > Output resolution	1080p (progressive)	The feed the monitor chapter sets for the F700
Output shooting infoSetup menu > HDMI > Output shooting info	OFF	A clean frame on the F700, as the monitor chapter sets

The button map shows the video controls this recipe changes or relies on. They live at Custom Setting g2, separate from the photo map, so a gimbal setup never disturbs your stills buttons.

Button map · Custom setting g2

Dance Video on a Gimbal

Custom settings menu > g Video > g2 Custom controls

Point at a highlighted control, or a name in the table, to match the two.

Control	Set to	Factory default	Why
Fn1 button	Power aperture (open)	White balance	Opens the aperture between phrases, with Fn2 beside it to close
Fn2 button	Power aperture (close)	Focus mode/AF-area mode	Pairs with Fn1 to close the aperture, set together with it
Sub-selector center	AE lock (hold)	AE/AF lock	Freezes exposure outdoors before a pan past the sky, where offered
AF-ON button	AF-ON	AF-ON	Default role, and it starts Subject-tracking AF on a soloist
OK button	Select center focus point	Select center focus point	Default role, and it ends tracking and recentres the point
Video record button	Record videos	Record videos	Default role, so clips start and stop on the camera itself

10.Beginner Mistakes

Leaving Auto ISO on for a stage show. The fade the lighting designer built turns grey and noisy as the camera lifts it. Fix one ISO at the rehearsal with Auto ISO control (mode M) at OFF.

Trusting the camera to pick the right dancer. Wide-area AF (L) prefers the closest subject (p. 124). Frame for the dancer you want, or switch to Subject-tracking AF for a solo.

Turning on Electronic VR on the gimbal. It narrows the frame and caps the ISO while the motors already steady the shot. Keep it OFF.

Leaving the standby timer short. When it expires between pieces the F700 goes dark and AE lock (hold) lets go (pp. 308, 751). Set c3 Standby timer to No limit before the first piece.

Riding the power aperture mid-phrase. The change can show as flicker and may be heard on the soundtrack (pp. 109-110). Adjust between phrases, or not at all.

Switching to 60p and keeping 1/60 s. That doubles the shutter angle to nearly 360 degrees, and the leap you meant to slow down smears. Move the shutter to 1/125 s with the frame rate.

11.Related Chapters

• Video from First Principles: mode M, the 180-degree shutter and ND filters.
• Video Formats and Codecs: file types, frame sizes and frame rates.
• N-Log, HLG and Exposure Tools: tone modes, zebra and the wave-form monitor.
• Video Autofocus and Stabilisation: video AF, Electronic VR and the gimbal.
• Audio and Timecode: the external microphone route and timecode.
• Cards and Data Rates for Video: bit rates and how long a card lasts.
• HDMI and External Monitors: the F700 feed and the gimbal payload.
• Heat, Power and Recording Limits: clip length, heat and batteries over a long event.
• Custom Controls: the full g2 button map.
• Image Area and Crop: FX and DX in video.
• Shutter Types, Rolling Shutter and Flicker: banding under stage light and rolling shutter.
• ISO and Auto ISO: fixed ISO on stage, Auto ISO outdoors.
• Metering: matrix and AE lock (hold) outdoors.
• White Balance: a fixed value for video.
• Stage Dance Stills: the same theatre from a seat, for stills.