Low Light Camera Basics

LOW LIGHT CAMERA BASICS

Of course, security is not a sunrise to sunset thing. Although statistically speaking, more breaking and entering crimes occur in the late morning to early afternoon hours, we need our cameras to function well 24-7. Here are a few basics about low light cameras and what to expect from them.

Many years ago, Samsung and Panasonic were the first to develop a “digital nightvision” that became known as “sens-up” as called by the industry from then on. Sens-up, or frame integration, is mostly a useless feature for security use. Essentially, sens-up takes a digital time exposure and combines image frames to yield a brighter picture. Sounds good on paper but as with any time exposure in photography, anything moving in the frame will be terribly blurred. The same thing occurs here. So if you have a mostly dark parking lot and you turn on sens-up, you can make that parking lot look nice and bright but anything moving through the area will be a ghost with no detail or useable detailed information whatsoever.   Don’t rely on sens-up.

INFRARED LIGHT CAMERAS:

Infrared cameras can be very useful in some applications. Infrared cameras are equipped with a number of LEDs that emit light in the infrared spectrum that is visible by a camera sensor that is sensitive to that type of light (not all are). These cameras thus provide their own light source at night and can see in total darkness. There are a few limitations:

  1. First ignore the spec sheet that says a particular camera has an IR range = 125’ for example   That is one big lie! In my 30 plus years of testing these cameras, manufacturers will almost double the true useful range of the IR light on their spec sheets. They all do it. The brand name cameras do it too only slightly less than the off-brand import cameras. So if your camera says the IR range is 100’, don’t expect to see someone lit up like a Christmas tree at that distance.   50 or 60’ is a more realistic distance.
  2. IR light is kinda like the light from a flashlight only you can’t see it. A typical flashlight is a concentrated beam in the center that doesn’t spread out very wide. The same is true with IR light. This is why you generally don’t see IR cameras with wide angle lenses. If you have a IR camera with a Varifocal lens set to the wide setting, during the day you will see a nice wide image. At night, you will see the same wide image but only the center 60% (give or take) will be illuminated by the IR. This is not a reason to avoid an IR cameras but keep this in mind when choosing a location for your camera. Keep the important real estate in the center of the image.
  3. “Smart IR” is a wonderful thing especially if your IR subjects will be frequently close to the camera (like a back or front door, a close in shot of a walkway or hallway etc). What happens is a camera without this feature will crank up the IR output to the max because all it sees is darkness. When a person walk into that dark frame, the camera will seriously over expose the image and you bad guy will look more like a washed out ghost. While this is better than nothing, the “smart IR” feature will solve this problem and yield more properly exposed images even if the person wanders very close to the camera (like doorway cameras). Our  analog Telpix IB-6335MV is equipped with this feature and puts out a great picture even if the person is only 2 or 3 feet from the camera.
  4. Most IR cameras have a red glow at night when you look directly at them. This is normal.

 

DAY/NIGHT CAMERAS:

The lower cost “day/night” cameras (frequently called electronic day/night) are pretty much no better in the black and white night mode then they are in color. This is pretty much a gimmick and really does very little to enhance to cameras viewing ability at night. If this is what your budget can handle, you have nothing to lose. Run with it.

A better choice (and more expensive) is called a “true” or “mechanical ICR” day/night camera. Not to get too technical, but this has a mechanism that adds/removes a filter that allows the camera to see better under low light conditions. Day/night cameras switch over automatically to black and white imaging at night. A true day night camera will be your best choice if you need to see beyond the typical range of an IR camera at night. Use a good low light lens for the best results. A lens with an “f rating” of 1.0 or lower (like.95) is best.

Specs to watch – “minimum illumination” refers to the cameras ability to see in low light. The lower or smaller the number, the better the performance is. This is listed in lux or Lx which is a value of illumination. Ignore any specs relating to sens-up. As I said before, that feature is useless. Here are some guidelines for minimum illumination values from higher to lower:

.2 lux and above (larger) – expect poor performance at night – leave the lights on!

.1 to .05 lux – average. If your scene is really dark, think about adding some lighting to supplement.

.04 lux and below (smaller) – good. Even this camera will not see in a really dark area but this is the best available without infrared.

Which camera is right for you assuming that night viewing is important?   If your critical subject is about 60’ or closer, consider a good IR camera (avoid the cheap junk). If you need to see out beyond this distance, consider a good true day/night camera. With either choice, you may need to add some supplemental lighting to get the most of your nighttime images. Energy efficient bulbs make this viable option now. No camera is perfect under low light conditions but hopefully, this will help you get the most out of your CCTV system at any time of the day or night.

Please come see us at Pro Security Warehouse!

 

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Author: dlwyatt1

dlwyatt1 is a 35 year industry professional with a degree in low voltage systems engineering. He has designed multi-million dollar projects for fortune 100 companies and founded Pro Security Warehouse and Integrated Security Solutions 20 years ago.

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