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Does lighting affect the fps of a webcam?
Lighting affects webcams in a similar way that lighting affects photography. Factors like exposure time and shutter speed need to be considered, but unlike photography or even traditional videography, we don’t usually have the manual control over these settings that we would with a professional camera. That’s why lighting is so important when shooting something with our webcam, even if we’d prefer to have our room dimmed by the PC’s light (assuming you’re all about RGB).
A room light or basic lighting in a kitchen might be enough for a video conference or virtual tabletop RPG party, but if we want to add our faces to a Skyrim or Apex Legends stream, something like a Razer Kiyo or Elgato’s Key Light would help Eliminates any framerate drops due to poor lighting. (We all want to see your pretty face too!)
To understand how and why lighting affects a webcam’s fps, let’s look at some basic concepts of still photography.
Anatomy of a camera
When talking about photography, two words that come up frequently are aperture and shutter speed. Aperture is the width or width by which the lens aperture (“eye”) opens. If it’s wide open, it’ll let more light in, if it’s narrow, it’ll let in less light. In low light situations, the aperture should be as wide as possible to let in the most light because it’s less. This reduces the time you need to have the shutter open to properly expose the photo.
This is where we come into shutter speed, or how long the lens takes to open up to properly expose the photo. If you have a wide aperture, the shutter doesn’t need to be open that long, but if you have a narrow aperture, the shutter needs to be open longer to let in the same amount of light.
ISO (or the International Organization for Standardization, the governing body that sets sensitivity levels for camera sensors) is also relevant to photography because it measures how sensitive a camera is to light. A higher ISO means it’s more sensitive to light, which means your shutter can be open for a shorter period of time, and your aperture can be narrower. If you’ve ever seen something like ISO 400 on 35mm film before, that means how fast the film is in the light. The concept is the same for DSLR cameras.
Of course, webcams don’t have these specific fine-grained settings because they’re designed to be as intrusive as possible. But it helps to understand why lighting affects the fps of the webcam.
Shutter Speed and Frame Rate
In still photography, you can only use one shutter speed per photo, but you can shoot at any speed you want. For example, if you’re photographing a moving object, a slower speed will blur it, but a faster speed will capture it as-is.
For video, the shutter is still involved, but it stays open, whereas the electronic shutter simulates the function of a mechanical shutter as you shoot. When shooting, you are limited to a single shutter speed, which depends on the frame rate.
According to the 180-degree shutter angle rule, your shutter speed should be twice the frame rate. So if your fps is 60, your shutter speed should not exceed 8000ms or 1/125th of a second. Too slow or too fast can make movement on the screen look unnatural. Aside from the drop in bandwidth, this is why we sometimes see people making jerky movements on their webcams.
But we can’t manually control the shutter speed of the webcam, which makes good lighting all the more important.
lighter, higher frame rate
There is also a direct relationship between a camera’s frame rate and exposure time. Most webcams will shoot at 30 or 60 fps. However, the darker your settings, the longer exposure times and wider apertures you will need to properly illuminate your photo.
For all of you who like math, the maximum frame rate can’t be more than one divided by the exposure time. For example, if your webcam has a max fps of 60, but your exposure time is 200 milliseconds (milliseconds) to get a bright image, your webcam won’t be running at full fps because it’s working hard to make the screen as bright as possible. In other words, the frame rate drops to properly expose the video frame in low light conditions.
Again, this isn’t something we can control from a webcam, but some webcams do come with software that allows you to adjust exposure, or prioritize between exposure and frame rate for that reason (Logitech’s StreamCam does). You may notice that if you prioritize exposure, your video may appear a little choppy if your lighting is too low.
Thankfully, you don’t need a professional lighting setup to use the webcam’s fps cap, but it doesn’t hurt to use something other than an IKEA desk lamp. Your webcam has its limitations and will do its best to automatically adjust for different lighting situations, but it won’t be perfect in every situation.