Digital cameras are amazing. Even compact digital cameras selling for less than $100 take photographs with great resolution.
The point-and-shoot cameras are great – that is, as long as the subject of the photo isn't moving very fast.
If the photographer is trying to catch the moment the little soccer player kicks his first goal or when the black Labrador leaps in the air to snag the Frisbee, then he may find a picture of an empty field or a blue sky. The compact digital camera can take so long to react after you snap the shutter-release button that the moment has passed and the desired image is never captured.
The problem is called shutter lag.
“It's the No. 1 dissatisfier that we hear about,” said Bob Gann, Hewlett-Packard's digital imaging systems architect.
Avoiding shutter lag, or minimizing it in the next camera you buy – well, that's a tricky problem.
The first problem is that shutter lag isn't really shutter lag at all, but processor lag. (Feel your eyes glazing over already?)
When the photographer presses the button to snap the picture, sensors in the camera take a series of measurements. The processor calculates the distance to the object, determines the amount of light needed and even does some balancing for color and whiteness. The processor also may have special software to focus on faces, so those calculations are run.
In effect, the processor is analyzing a series of images as the button descends. Then the image is captured on the processor and sent into memory.
That can take almost as long as one second. So any consumer who wants to buy a fast-acting camera merely has to look at the specification sheets, right?
Well, no. Many cameras' spec sheets don't list any number that would help a consumer make a choice. The Nikon Coolpix S500, which the company said was one of its best performers for action shots, gave no clues. The Hewlett-Packard $230 PhotoSmart R837, its best contestant, lists only a “shot-to-shot time” of 1.5 seconds. Some reviews said it had “shutter lag” of 0.37 second. The Kodak EasyShare Z712 IS has a “click-to-capture” speed of 0.26 second.
Better proxies for estimating shutter lag are autofocus lag and shutter-release lag, if you can find those data. A conscientious shopper may find the information in reviews in camera magazines or camera Web sites. (Hint: Search the Internet for the camera name and the words “shutter lag.”)
If you already have a camera, a rough do-it-yourself test is available at www.shootingdigital.com/columns/
schwartz/shutter_release_test/default.asp. But it's influenced by how fast your reflexes are.
Another measurement that plays into catching action shots is ISO. It's a term that was transported over from silver-halide film, when it measured the fineness of the grains on the film, hence its sensitivity to light. A higher ISO could capture action better in low-light conditions.
So the higher a digital camera's ISO settings, the more able it is to nail the action shot. The $300 Kodak Z712 IS goes up to 3200.
“It might not be shutter lag, but it could be the camera system may not be robust enough to capture it,” said Jerry Magee, product manager at Kodak.
If true, that presents an even bigger problem for consumers: They have to evaluate the quality of the chip inside the camera, a difficult job because information about the type and maker of the processor isn't readily available.
Some camera magazines refer to the processor, but camera buffs who write for them tend not to be electronic engineers who can describe the advantages of a Texas Instrument chip over a Zoran chip.
“I'm not sure the customer needs to know that much about the processor,” said Steve Heiner, a senior technical manger at Nikon.
The shutter-lag problem isn't true of all digital cameras. The digital single-lens-reflex, or SLR cameras don't struggle with it. Indeed, if someone takes a lot of action photos and is bothered by shutter lag, the solution is to spring for a more expensive digital SLR model.
The good news is that the lowest end of this category has touched the upper end of the compact-camera category. The Nikon D40, that maker's cheapest digital SLR, sells for about $530. A Sony DSCH9/B, a 7-megapixel point-and-shoot, albeit a pretty fancy one, goes for about $480.
Photographers offer a few tips on capturing action shots with point-and-shoot cameras. If you can anticipate a shot – for instance, a birthday cake's candles about to be blown out – then push the shutter-release button down halfway. Priming the autofocus gets the process started early. When you push the button down all the way, the camera can process the information more quickly.
Another trick is to point the camera to where the action will occur, push halfway, and when the action occurs, push it all the way. That means you don't follow the subject; you follow the event. In other words, if you are tracking a downhill skier slaloming through a series of flags, aim at the flags, not the skier.
Camera makers also suggested using the burst mode, which quick-fires a series of photos. Shoot the first one in advance of the event and then you'll probably capture the significant moment.
Many cameras have a pets or children mode to capture those things that won't stand still when instructed.
“It works pretty well when you have enough light,” said Chuck Westfall, a spokesman for Canon.
As cameras simultaneously drop in price and add more features, concerns about shutter lag will diminish.
“Give us a few more years and you won't be hearing about it,” Gann of Hewlett-Packard said. “But it adds costs. We know how to make it faster, but it would cost money.”
