How to photograph LED walls and screens on a stand

Why screens band

An LED panel does not show a steady picture. It refreshes hundreds or thousands of times a second, and between refreshes the pixels are briefly dark. A camera reads the scene over a short window, usually from the top of the frame to the bottom. When the shutter window and the refresh cycle do not divide evenly, the sensor catches part of the panel in one refresh and part in the next: a dark band across the wall in a photograph, or a band that rolls up the screen in video.

Rental panels used on Dubai stands commonly refresh at 1920 Hz or 3840 Hz; the higher the rate, the easier the panel is to photograph. Cheaper panels and monitors refresh more slowly and band more. Phones make it worse because they choose their own shutter speed. Cameras with a manually set shutter speed, and for video a set shutter angle, make the problem manageable on almost any panel.

The walk-through test

Every screen on the stand is tested before doors, during the walk-through on opening morning or at the end of the last build-up day once the content is loaded. The test takes two or three minutes per screen.

1. Ask the AV supplier for the panel's refresh rate; if nobody knows, the test finds it anyway.
2. Photograph the screen at a series of shutter speeds, typically from 1/30 to 1/250 of a second, and check each frame at full magnification for bands.
3. Note the fastest clean speed; it is usually one that divides evenly into the refresh rate. That speed is used for every frame that includes the screen.
4. For video, set the frame rate (25 frames per second for most deliveries in the UAE) and adjust the shutter angle until the rolling band disappears on the monitor, then lock it.
5. Repeat for each screen, because a 55-inch counter monitor and a 4 metre LED wall rarely behave the same.

The settings go in the crew's notes so the second photographer and the video operator use the same ones.

Exposure and colour: the screen against the stand

An indoor LED wall is far brighter than the stand lighting around it. Exposed for the stand, the screen blows out to white; exposed for the screen, the stand goes dark. For the clean set we ask the AV technician to bring the wall's brightness down, often to between a third and a half of its show setting, so that screen and stand sit within the same exposure. The visitor's eye does not notice the change; the camera does.

Colour is a second mismatch. The screen's white point and the stand's lighting are rarely the same, so white balance is set to the screen where the screen is the subject and to the stand lighting for the wide shots, and the two are matched in grading so the brand blue on the wall and on the panels is the same blue. The stand lighting guide covers the rest of the stand's light.

What to put on the screen

For the clean shot, a still frame reads better than a rolling video: the hero visual, the product or the logo on a brand colour. Ask the stand team to pause the loop on that frame for five minutes before doors. Avoid bright white backgrounds, which blow out against the stand lighting, and fine stripes, grids or small text, which produce moiré. Check that the content is sized to the wall; a 16:9 video on a 3:1 wall shows black bars in every photograph of the stand.

For film, rolling content is fine and often better, because a moving wall behind a visitor gives the recap film energy. For interviews in front of a wall, a slow, dark loop is better than a bright, fast one, which pulls the eye from the speaker. Remove the cursor and the media player's control bar; both appear in more stand photographs than you would expect.

Reflections, moiré and angles

Glossy monitors and glass-fronted displays reflect the hall's roof lights and the neighbour's stand; a step to the side or a change in camera height removes the reflection, which is why the clean set is photographed from several positions. Fine pixel patterns can produce moiré, a shimmer that was not on the screen; a change of distance or focal length removes it. Both are checked on the back of the camera on the day.

A screen photographed from a sharp angle loses brightness and shifts colour, especially on older panels, so the frame that shows the screen best is taken close to straight on, at the height of its centre. If the wall is above head height, the wide shot from the aisle shows it correctly and the detail is taken from a step or the upper level.

A scenario: a 4 metre wall at GITEX

A software exhibitor with a 4 metre by 2.5 metre LED wall and two 55-inch counter monitors at Expo City Dubai for GITEX Global. 08:50: the crew arrives on exhibitor badges; the AV technician is already running the loop. 09:00: the test finds 1/100 clean and 1/125 banded on the wall, so 1/100 goes in the notes; the monitors are clean at 1/60. 09:10: the technician brings the wall to half brightness and pauses the loop on the product visual. 09:15 to 09:45: the clean set from the aisle, the three-quarter views and the detail of the wall with the logo. 09:45: wall back to full brightness, loop restarted, settings locked. 10:00: doors.

Through the day the wall appears behind visitors, the demo and two interviews, clean in every frame because the test took ten minutes.

Who does what

The AV supplier knows the refresh rate and controls brightness and content; ask for a technician on the stand for the walk-through, which most include in the hire. A list of AV and staging companies in the UAE is on the resources page. The stand builder provides the content loop and the hero still, and benefits most from the clean set; the stand builders page covers how that set is delivered. The crew tests, sets, photographs and grades, and delivers the set the same evening with the screen looking as the visitor saw it. The LED wall glossary entry summarises the terms.