At this time of year lots of people are considering the purchase of a new camcorder. High on many people's list of features is the ability to shoot video indoors or outdoors at night in what is commonly referred to as "low light" conditions. The first thing you should know is that "low light" is a very subjective term. What one person means by low light is often different from what someone else means. I'll try to clear up that problem and address some other things to consider as you try to decide if a certain camcorder meets your needs or you compare different camcorders.
Consumer Camcorders Don't Record Well In Low Light
You're going to find that most consumer-grade camcorders under $1000 don't work too well in low light. This is because of several factors. Because of the desire to make camcorders smaller and smaller and to include a still photo feature, camcorders manufacturers put very small
CCDs with a large number of
pixels on them in their consumer camcorders. Small CCDs mean only a small amount of light will register on them and the large number of pixels means each pixel will only get a small amount of that light. As a result, it takes a large amount of light to get a good, sharp image on tape. As you might expect, a camcorder with larger CCDs and fewer pixels will usually work better in low light conditions.
Of course, as in much of life, there are tradeoffs to be considered. Fewer pixels usually means less sharpness in the video, all other things being equal. And all other things
aren't usually equal so simply going by pixel count won't always tell you which camcorder is better. The only real way to tell is to shoot some video and see how well the cam performs. Not always practical but that's the way it is.
Camcorders Don't Work In No Light
Every so often someone will be looking for a camcorder that works in complete dark. When you think about this for a second you realize there is no such thing. Camcorders (and all cameras, digital or film-based for that matter) work by recording reflected light. If there is no light to reflect off things there obviously can't be anything to record.
Some cams say they work with no light, so what gives? These usually accomplish this by using an on-cam infrared light source and CCDs that are sensitive to infrared light. So there really is a light, it's just not one you can see. These cams usually take those greenish, night vision images you've seen in TV news or war movies. That's not the kind of thing most folks want for their video but for certain surveillance-type applications it might be adequate.
The Mysterious Lux Rating
The measure of light you'll see associated with camcorders is the
lux. Virtually all camcorder specs include a lux rating. Many cams offer relatively low lux ratings, usually in single digits or low double digits. But be sure to check the specs for how they achieve this. These cams sometimes work by using some kind of "night mode". Night mode often uses a slow shutter speed or increased
gain as a way to increase the amount of light that gets recorded. One thing usually not mentioned in the specs is what the video looks like with these low light modes. In other words, they claim the cam will record images in extreme low light but they don't say whether you'll be able to tell what you recorded. Slow shutter speeds will produce blurry video if there is even the slightest movement by your subjects or the cam. Increased gain will produce graininess due to increased video noise in your images. Color rendition will often degrade in night mode, too, and auto focusing often doesn't work as well as in better lighting.
Something else to consider; although a standard is in place in the United States to specify minimum quality standards for light levels, adherence to this standard is not mandatory. Since manufacturers know that consumers want cameras that shoot under low light levels, they are reluctant to use that standard and look inferior to a competitor who is not adhering to the standard. So beware of the claims manufacturers make for low light capabilities.
So How Much Light Do I Need?
You can measure the amount of light when you are shooting by using a
light meter. Some are calibrated in lux and one of these meters would give you a good reading on what you are dealing with. But, most of us don't want to spend the money on a light meter nor do we need such precision in determining how much light there is in a scene. So, as a guide to light levels in typical conditions you will encounter, here are some light examples from "Digital Video Pocket Guide" by Derrick Story from O'Reilly.
100,000 lux.....directly lit by bright sunlight
10,000 lux......full daylight
1,000 lux.......bright overcast day
500-1,000 lux...open shade on lightly cloudy day
500 lux.........brightly lit natural light interior; multiple windows with no added artificial light)
150 lux.........commercial artificial lighting indoors (typical shopping mall with no added daylight)
100 lux.........dark overcast day (high quality threshold for most camcorders in daylight mode)
100 lux.........typical restaurant or coffee shop artificial lighting (bright enough to easily read menu)
50 lux..........room lit by single ceiling light bulb (lightly painted walls, 100 watt bulb)
10 lux..........early twilight
10 lux..........light from 60 watt bulb from 10 feet away
1 lux...........late twilight
0.1 lux.........full moon
This list is a pretty good guide to how much light you'll need (or how low a lux rating your camcorder will need) to record video in different conditions. But note that as I mentioned above, this doesn't necessarily mean you'll get good video. But at least you'll know that most consumer camcorders won't do a good job of recording your newborn asleep lit only by a night light.
To underscore the need for at least 100 lux to get decent video, one magazine, Camcorder and Computer Video, in its camcorder reviews always lists the manufacturers lux rating with the following caveat: "However, for good video, C&CV recommends illumination of 100 lux or more.)"
So, armed with some knowledge you should now be a better shopper as you go about the sometimes daunting task of trying to figure out which camcorder meets your needs but won't break your budget. You may not find exactly what you need in your price range but at least you won't be unhappily surprised on Christmas, Chanukah, Kwanzaa or whatever holiday you celebrate as you try out that new camcorder in the light conditions you will encounter.
Happy shooting.
Good luck.
Dennis
Maybe Mr. Smarty Pants Astronomer would like to suggest something better. 
Great post Dennis!
Linear Mode
