How far do spotlights have to be to prevent strobing?

Have you ever found it challenging to focus due to the flickering of lights or a strobing effect in a particular event? This strobe effect, defined as persistent flashing or turning off and on of the lights at close intervals, is known to cause visual discomfort and even health-related issues. This effect can also be noticed during video recordings, affecting the overall quality of the capture in an undesirable manner.

Strobing usually occurs due to a mismatch of the light sources’ frequency with either the camera frame rate or the human frame perception. This article will discuss the meaning of strobing, the reason for its occurrence and various methods that can be utilized to ensure that lighting systems are properly designed in order to eliminate strobing effects thus improving the visual experience, in addition to health.

What is Strobing and How Does It Happen?

Strobing in the simplest is the rapid throwing or refracting rays of light on an object so that a pulsing effect can be experienced through ones eyes or through a video. This is a flash gun where the bulb is flashing on and off at a rate too slow to the human eye or camera as to be ignored thus giving the illusion of non-continuous played videos.

Definition of Strobing

Strobing refers to the effect created when light flashes and pulses in quick succession, typically at a frequency (speed of flash) that can be observed by human eyes or video devices. In most of the instances, the light apparatus being used is not consistent enough resulting in a flash that flickers in a manner that compromises the even flow of lighting that one is used to.

How Does Strobing Happen?

Strobing usually happens because of two main reasons:

Low-Frequency Lights

• Some older light bulbs, such as fluorescent lights or certain types of LED lights, operate at a low frequency. These lights pulse on and off many times per second. When this happens at a frequency that falls within a range of about 50 to 60 Hz (times per second), the flicker is visible to the human eye or can be recorded by cameras.

• For example, the fluorescent lamp will work at about 50Hz to 60Hz, which indicates that the tube light is switching on and off at a rate of 50-60 times per second. Though the human eye may sometimes fail to catch each flash, it can register the effect as a whole, which can be expressed as irritation or as an unnatural motion.

Poor Synchronization with Video Equipment

• Another common cause of strobing happens when the light isn’t synced properly with the frame rate of video equipment (the number of frames per second, or fps).

• Video cameras record images in rapid succession, and if the light source is flickering at a rate that doesn’t align with the camera’s frame rate, the camera will capture different moments of the light’s on-off cycle, resulting in visible flicker or strobing effects in the footage.

• For example, if a camera is recording at 30 fps but the light is flickering at 50 Hz, the camera might capture the light’s “on” state in one frame and its “off” state in another frame, causing a strobe effect on screen.

Technical Explanation

• Flicker Visibility: The human eye and video equipment are sensitive to flicker when it occurs at a frequency that matches or is close to our perception range. Most people can see flicker at 50 Hz to 60 Hz, which is why lights operating at these frequencies can be noticeable.
• Light Synchronization: Strobing can also happen if the frame rate of video equipment (such as 24 fps, 30 fps, or 60 fps) does not match the light frequency. Cameras are capturing a sequence of frames in a short amount of time. If the lights turn on and off more frequently than the camera’s ability to capture them, it results in the strobing effect, creating uneven lighting in the footage.

Why Strobing Is a Problem?

Even though the phenomenon of strobing is commonplace, it often gets overlooked in the daily tribulations of most individuals; however, it does have adverse effects – mostly some environments. A light’s Turning On and Off rapidly – even if in public areas, during a concert or in a video which does not necessarily feature a bright spotlight – is irritating and sometimes dangerous. Now, let’s analyze the primary issues that arise from the practice of strobing:

Health Risks

Strobing light effects are not only irritating but can also have severe health implications especially among individuals who have difficulty with flicking lights. The on-and-off cycling characteristics of the light can cause several physical and psychological problems, including.

Headaches and Eye Strain: Light with mobility at a higher speed than average produces irritation when trying to focus leading to headaches and eye pain. Nausea and lightheadedness may also occur. This effect can be more pronounced in people with light sensitivity and particularly in poorly lit or dark environments.

Epileptic Seizures: One of the most serious health risks associated with strobing lights is the potential to trigger seizures in people with photosensitive epilepsy. The flickering light can disrupt brain activity, leading to convulsions or loss of consciousness in extreme cases. The flashing light from strobe effects, especially in high-frequency flashes, has been known to induce seizures in sensitive individuals, often at events like concerts, festivals, or nightclubs

Technical Explanation

• Flicker Visibility: The human eye and video equipment are sensitive to flicker when it occurs at a frequency that matches or is close to our perception range. Most people can see flicker at 50 Hz to 60 Hz, which is why lights operating at these frequencies can be noticeable.
• Light Synchronization: Strobing can also happen if the frame rate of video equipment (such as 24 fps, 30 fps, or 60 fps) does not match the light frequency. Cameras are capturing a sequence of frames in a short amount of time. If the lights turn on and off more frequently than the camera’s ability to capture them, it results in the strobing effect, creating uneven lighting in the footage.

Past Incidents

The most notable incident involving strobing lights causing health problems occurred during a Pokémon episode in 1997. The episode, “Denno Shenshi Porygon” (Electric Soldier Porygon), featured a rapidly flashing red and blue scene due to Pikachu’s thunderbolt attack. This intense strobe effect, which occurred at a frequency of 12 Hz, triggered seizures and other symptoms in many viewers, especially children.

 Over 600 children were hospitalized, some even requiring intensive care. The episode was quickly pulled from airing, and this incident led to significant changes in Japan’s broadcasting regulations, including warnings about flashing lights on TV programs. It became a pivotal moment in the history of media safety, particularly concerning photosensitive epilepsy

Impact on Video Quality

Strobing is a major problem when filming at high to ultra high quality. With excessive lights at low frequency strobing effect causes interruptions while video recording.

Flickering in Footage: Cameras work on the concept of taking stills in a given time i.e. in frames per seconds. Thus, whenever the fps of the camera is not matched to that of the light, an illusion of variation in the light is created. Such variance results in unwanted flickering or strobing of the video making the video unrealistic or irritating.

Reduced Visual Clarity: Strobing can produce some blurred discomforting images that may easily lose the audience’s attention from the content which is a negative aspect. This is more so the case in occasions such as concerts or stage performance that involve live transmission or recording with the audience watching since there is a requirement for proper lighting throughout.

Unpleasant Viewing Experience: In the case of professional filming or video recordings such as TV shows, movies, commercials, etc. strobing disrupts the recording quality of the video making it less appealing thus creating discomfort to the viewers.

Past incidents:

Ozzfest 1999 used strobe lighting at the concert, which led to disruptions when recorded footage was aired on TV. Viewers watching on TV or live broadcasts saw flickering visuals, leading to blurry footage and visual inconsistency. Just like in your examples, the frame rate mismatch between the strobe lights and the cameras caused the strobing effect, making the footage unnatural and distracting, affecting the quality of the viewing experience.

Real-Life Examples of Strobing Incidents

Strobing lights are a powerful visual tool often used in concerts and other live events, but when used excessively or without proper regulation, they can have unintended harmful effects. Below are a few key real-life incidents where strobing or flickering lights have caused problems for individuals and audiences:

1. Electric Daisy Carnival (EDC) – Seizures Triggered by Strobe Lights

At the Electric Daisy Carnival (EDC), a major electronic music festival known for its vibrant light shows, strobe lighting is often a key part of the event’s visual spectacle. However, the intensity and rapid frequency of flashing lights at these events have been known to trigger photosensitive seizures in some individuals. For example, during the 2015 EDC in Las Vegas, there were reports of seizures being triggered by the excessive use of flashing lights. The rapid flickering of lights, paired with loud music and intense visuals, created a dangerous combination for people sensitive to these effects.

Such incidents highlight the potential dangers of using strobe lights without proper consideration of audience safety, particularly in large crowds where medical assistance may be delayed or hard to access quickly

2. Retail and Public Spaces – Flickering Fluorescent Lights Causing Discomfort

Strobing effects aren’t limited to concerts. Poorly maintained or flickering lights in everyday public spaces, such as supermarkets, offices, and malls, can cause discomfort and even lead to physical symptoms such as dizziness, headaches, or eye strain. For example, many supermarkets use fluorescent lighting, and if these lights flicker, even at a subtle rate, it can lead to visual discomfort for customers and employees. In some cases, this flickering has even led to reduced productivity in work environments as employees struggle to focus or experience discomfort.

In fact, some studies have shown that flickering lights can have negative health effects over time, especially in workplaces with poor lighting conditions. People working under these conditions may experience increased fatigue and reduced concentration, affecting both their well-being and their productivity…

How to Avoid Strobing in Lighting Systems

1. Choose High-Quality Lights

Select LED Lighting Technology without Flicker: Unlike the conventional LED lights, modern LED lights that have been designed with the flicker free technology have constant light oscillation. These are made using high refresh rates (100 Hz and above) making it impossible to see changes in the brightness when viewed through a camera or in a high speed environment.

Positives: When the performance or a recording is done with flicker-free lights, the quality will be better than when these lights are not used. Comforts for the users are increased as well. These lights do not cause eye pressure, headache, fatigue as flickering lights with poor designs do.

Pro Tip: Do pick ‘flicker-free’ lamps or other lamps that comply with international low flicker criteria such as IEEE Std 1789.

2. Synchronize with Camera Settings

Understand Frame Rate vs. Light Frequency: One of the most important things to understand when using video cameras is the frame rate at which they normally record video (for instance, 30fps, 60fps) versus the operating frequency of most lights (for instance 50 Hz or 60 Hz). When these two are not balanced, strobing will occur because, in the video footage, the light seems to flicker in an uneven manner.

How to Fix: This light’s frequency and the camera’s recording frame rate need to be synchronized. For example, if the light source is at 50 Hz, it is advisable to use frame rates of 25fps or 50fps for suitable video recording.

Practical Application: The shutter speed and frame rate of many professional cameras can be adjusted; vary these for optimum output.

3. Test in Real Environments

Conduct Pre-Event Tests: Make sure to test the lighting setup in the space where it will actually be used before a production or recording takes place. This would help to locate any flickering issues and resolve them before they affect the outcome of the work.

Tools to Detect Flicker: Analyze the lighting system using applications for phones or light flicker meters. These devices can help catch symptoms that can’t quite be seen but would otherwise show on a recording within seconds.

Regular Maintenance: This issue is especially preponderant in flickering light fixtures with old and dilapidated upkept lamps. Make sure the condition of your lights is fine and any broken parts are fixed without delay.

Technological Advancements to Prevent Strobing

The development of lighting technologies has made significant strides in minimizing or completely eliminating strobing effects. Here’s a look at the latest advancements:

1. High-End LED Lights

• Flicker-Free Technology: The latest models of LED lamps are designed to offer smooth and even light emission. They are designed to operate on high refresh rates, thereby minimizing strobing effects. Such lights are perfect for any sensitive content production including filming, photography, and office environments.

• Widespread Use:: These lights have just become a staple in manufacturing and engineering sectors that place a lot of emphasis on visual quality and user enjoyment. More often than not, they also come with low flicker certifications.

2. Smart Lighting Systems

• Customizable Settings: Current smart lighting systems allow users to manage different parameters including brightness, color temperature and frequency among other controls. Such extreme levels of control allow users to customize people lights to avoid strobing effects of light according to individual preferences.

• Dynamic Adjustments: A few of the systems are the systems that change real time due to the controls by devices like cameras or by the environment in order to avoid flickering. Integration into a smart home or smart studio system gives an even more degree of freedom.

3. Research and Development in Lighting

• Adaptive Light Controls: Ongoing innovation has led to the development of adaptive technologies in lighting. These lights can automatically adjust their output based on surrounding conditions, ensuring a steady and flicker-free experience.

• Innovative Designs: Manufacturers are incorporating improved drivers and enhanced dimming technologies to eliminate flicker, even at lower brightness settings.

Conclusion

In order to prevent strobing effect in lighting, one has to utilize the flicker free lights, preferably modern day LED lights, and ensure that proper synchronizations are adhered to with the equipment. Testing the lights in actual scenarios helps in identifying any signs of flickering in advance. Appropriate lighting is selected based on ensuring comfort, safety and quality whether it’s a casual surrounding or for work. Use of better devices will enhance home and work life in equal measure.