high shutter speed example

WDR and Shutter Speed: What Does It All Mean?

Demystifying Home Security Camera Specs

When you look at the specs for home security cameras, you may see some confusing numbers and abbreviations. It’s like a secret code that you don’t fully understand. Before you can find the best home security camera for your home, you need to ask yourself one question. What does it all mean?

Shutter Speed

You may already know to look for a camera with the lowest shutter speed, but why does it matter? Shutter speed is the amount of time needed to take a single shot. A short shutter speed translates to a quick shot, and this value is usually measured as a fraction. The lower the fraction, the less time it takes to get a shot.

All good to know, but it doesn’t help much if you don’t understand how it applies to a home security camera. When images are captured by a video camera, they may seem clear until you try to capture one specific frame. A camera with a slow shutter speed takes too long to take a picture of a moving object, and the image ends up being blurry.

There are a few scenarios ideal for cameras with fast shutter speeds. A stationary camera with a lot of motion in the background needs a camera with a low shutter speed so that you can see the objects in motion, like the picture of the hummingbird above. Similarly, a moving camera that pans over an area with stationary objects needs a low shutter speed. If you want your home security camera to be able to show license plate numbers or have clear views of faces, it needs a fast shutter speed.

WDR

You may notice the abbreviation WDR on home security camera specs. This stands for “wide dynamic range,” a term that sounds more confusing than it is. Simply put, WDR is a function on a camera that makes images clear even when the lighting isn’t ideal.

When lighting is very bright and very dark in the same frame, cameras without WDR can’t capture details in both areas. The bright areas might be too bright to make out any details, or the dark areas may have too many shadows. With WDR, you can make out the smallest details in the whole frame, bright and dark alike. That strange glow of a subject that sometimes appears in overly bright images is no longer an issue.

Most cameras without WDR work by adjusting to the average brightness of the area in the image. In rooms that have a wide range of brightness, this adjustment isn’t very effective. The darkest spots or brightest spots aren’t considered, and certain objects in the image end up becoming unclear. The WDR function works by filtering the backlight around an object. In doing so, the camera is able to get a much clearer image of the object.

Having the WDR function is extremely useful for security cameras. If your camera is in a room with many windows, you need WDR. Otherwise, the bright light from outside your home will be a problem and the subjects in your image won’t be very detailed. A camera pointing to a single window or door is also an issue without WDR. During the day, the light coming in from the outside will contrast with the darker areas and these darker areas will be covered in too many shadows to see clearly.

HDR

HDR stands for “High Definition Range”. HDR is an old photo processing technique that is new to video surveillance. Just like WDR, HDR is a function on cameras that makes images clearer in situations where there are extreme differences in lighting.

Though HDR and WDR perform the same basic task, they approach the task differently. Cameras with HDR take many shots of the same frame with different light exposures. Then software is used to combine the images in real-time to produce the highest quality video image possible. Cameras with this function can capture twice as many exposures per second as a standard security camera. This means the software has more options to choose from to help provide the best combination with the most detail.

You can use a camera with HDR in similar situations as a camera with WDR, like the camera pointing at a single window or door and rooms with many windows. Another great place is outside where cameras may be exposed to headlights from passing cars at night.

Clear Images

You don’t need to look at the specs for a home security camera and hope for the best. Having an understanding of WDR, HDR, and shutter speed takes the mystery out of the search for a good camera and can mean the difference between a clear image and a blur.

FEATURED IMAGE: Violet Sabrewing Hummingbird in B and W by Steve Corey used under a (CC BY-NC 2.0) license. No changes made.