Going through the photographs of yesterday’s snowstorm, I came to the painful realisation that I need a light meter again: it’s a pretty essential piece of gear, even for digital photography. (By the way, the following info is for photography newbies only… more advanced folks will probably laugh their way through my feeble attempts at explanation.)
A lot of the better digital cameras nowadays can take manual exposure settings, so when the situation necessitates it, you can jump into the controls and set the f/stop (the aperture, or the size of the opening that lets light into the camera), the shutter speed (how long light is allowed onto the sensor), and the ISO (the film speed, or at least the digital equivalent). Now, most cameras have an automatic setting, and they do a pretty good job of figuring out the exposure by selecting the fastest shutter for the existing light situation. Some will let you vary the shutter speed, the f/stop or the ISO, and everything else adjusts for you.
But there’s a problem with this. Most cameras set the exposure by reflective metering — that is, by the amount of light reflected back onto the sensor from the subject. There’s a bit of mathematics happening behind the scenes to find the shadows, mid-tones and highlights, and spread the tones appropriately. (This is a simplification, I know, but bear with me.) But what happens when the tones don’t cover the whole gamut from black to white, or if there’s far more of one than the other? The sensor gets confused, and the algorithms don’t work. For example, almost all of my snowstorm pictures were overwhelmingly mid-tone (50%) grey where they should have been white. Consequently, all of the photographs needed to be brought into Photoshop so I could adjust the levels and curves and make them look somewhat acceptable.
Now, a good light meter not only offers reflective metering, but also incident reading. This is the amount of light actually falling upon your subject. Thus, it’s far more reliable for scenes with snow, glare, sand and other situations that would confound a reflective meter. You simply go into the same light as your subject, hold up the meter so that the little dome or cone is facing your camera, and you can get an accurate reading. Adjust to your desired shutter speed, ISO or f/stop, and the meter will recompute the exposure and show the settings that you can manually enter in your camera.
There’s a wide variety of meters, but you needn’t pick up a new, expensive digital one –about $250-500 USD or more– unless you’re shooting professionally (in which case, you already know all this). It’s often possible to purchase used analogue meters from pawn shops and pre-owned camera stores. Just make sure that it has incident reading (some only have reflective), and you can figure out how to use it — some of them can be a little complicated. I wish I had picked up a decent little one I saw in Nova Scotia for $25 CDN when I had a chance: the one I used back in high school went missing somewhere along the line.
I find it a little odd that several of the recent photography books I own don’t even mention the light meter (or, if they do, it’s a tiny paragraph in a sidebar); surely, digital photographers ought to know how to set a proper exposure without crossing one’s fingers and hoping that the camera gets it right. Constantly reviewing the output and histograms and reshooting is certainly no substitute for a decent incident reading in the first place. As I mentioned earlier, most cameras do a decent job with figuring out exposure settings. But grab yourself a light meter, and you’ll probably find a noticable improvement in your photographs, especially in winter conditions, on the beach, or near shining glass or water.
Anyone out there recommend a good but inexpensive meter, preferably digital?