By Dr. Samuel Centralia, Ph.D., D.D.S., Esq.

So I was up on the Observation Deck the other night, charting some debris clusters near the Cygnus Loop, when my telescope lens exploded with light. "Supernova!" I thought, and reached for my notepad. I've had a little side hobby for years now of scouting spiral galaxy cores for NASA. Nice people, but surprisingly amateurish when it comes to charting interstellar clouds.

Then several dozen fireworks detonated around the observation deck, and I realized the situation -- the neighborhood kids were attacking with bottle rockets. (They call me "Crazy Doc" around here and like to pull pranks.) The adorable little rascals. Of course, they don't know about my ongoing experiments with the neighborhood water supply. Wait'll they hit puberty. Then we'll see who's laughing.

Anyway, moving along …

Ah, yes -- the digital camera. Marvelous contraption, really. In years to come, our grandchildren will marvel at the idea that we once used film and chemical processes to develop still images. It shall seem quaint to them, like a butter churn.

However, as is typical with today's advanced gadgetry, the befuddling array of available options can make the buying process rather confusing. Here are three general things to keep firmly in mind:

• Megapixel Mania (Or: Don't Believe the Hype). Yes, more megapixels are nice, but how often do you need billboard-sized prints of your kid’s soccer game? 5-8 MP is plenty for almost every conceivable use (and 5 MP is really all you'll ever need if you're looking for a family snapshot camera).
  
  
• Don’t skimp on the memory card. It’s separate from the camera, but in this day and age, get at least a 512MB flash card (1GB is better). It will give you more than 200 pictures at its highest setting -- always shoot at the highest setting -- and allow for plenty of boo-boos, videos, etc.
  
  
• Anti-shake/image stabilization. Digital cameras are notorious for producing blurry images when taking hand-held shots. Image stabilization is the Next Big Thing in this field, and it’s a good feature that really can improve matters nicely.

Now, let's dig into some additional details, shall we?

Megapixels

Megapixels indicate the maximum resolution that a camera can capture -- lower-resolution images become grainy or pixelized when enlarged. This is the number that gets bandied around most in comparing digital cameras, but actually the issue is quite simple. What are you going to use the camera for?

• For online or digital reproduction -- eBay, website, e-mail, craigslist personals (hey, I'm not judging) -- 2-3 megapixel cameras are dirt cheap and work just fine.
  
  
• For regular "family camera" use, 6 megapixels is minimum (and, happily, pretty much standard nowadays.) This will ensure that you can print your pictures to typical format sizes with no resolution problems.
  
  
• Higher megapixel cameras are really aimed at professionals, and allow for oversized prints and/or advanced image manipulation. Also good for espionage work, if you happen to be a double-agent working under deep cover in Prague. Just saying.
  
  

Optical zoom vs. digital zoom

When comparing here, always look for the optical zoom numbers. Optical is a mechanical function of the lens, just as with "analog" cameras. Digital zoom is simply computer-generated magnification, which extrapolates image data and actually decreases picture quality. Essentially, everything you've seen in sci-fi movies about computer magnification is wrong.

Many cameras combine optical and digital zoom stats into an "overall" zoom rating. Ignore this (politely) and check that optical zoom again.

Pocket size, purse size, bag size…

While it's certainly fashionable these days to have the smallest digital gadget available (see cell phones, iPods) optical zoom is the real issue here.

• Thinner, smaller cameras tend to have lower optical zoom (see above) but do have the benefit of being impressively tiny -- in many cases, literally pocket-sized. Again, good for espionage.
  
  
• The larger cameras, conversely, tend to have better optical zoom. It's a mechanical issue, you see -- the interior lenses need to move physically farther apart to improve zoom, and there's no way to digitally miniaturize that process.
  
  

Features

Time Delay

• Look up the delay. Slow trigger speed is one of the factors that contribute to the blurry images of older and low-end digital cameras. It's less of an issue, but time of press-to-picture is important, too. Some cameras have a regrettable delay that can ruin action shots, no matter how fast your trigger finger, Tex.

LCD Size

• This has become more important lately, as fewer cameras have optical viewfinders at all. That is to say, there's no little hole to look through anymore, so your LCD display is all you got. This is where brightness becomes a factor, as it can be hard to see a LCD display held at arm's length at high noon.
  
  
• Larger, brighter LCD displays also make for better in-camera viewing in playback mode.

Battery Life

• Obviously, you'll want enough battery life to do a full day's shooting, at least, on a single charge. This isn't likely to be a problem, unless you're planning to take several hundred pictures, or a lot of indoor shots with flash.
  
  
• A good rule of thumb is to take the manual's claim on battery performance, and reduce by 20 percent. You can take this approach with virtually all battery-powered gadgets, as manufacturer stats are always based on ideal, laboratory conditions. I mean, I tend to live in ideal laboratory conditions, but that's personal predilection.

Video Recording

• This is an option found on most cameras now that allows you to record a short amount of low-grade video footage. For TV resolution, 480 horizontal lines of resolution is becoming more common. Dig around on the video recording specs if it's something you think you'll use. Some let you record and take pictures simultaneously, also a nice feature.
  
  
• Privacy advocates tend to worry about this, along with cell phone video cameras -- what happens when everyone has a video camera in their pocket, all the time? We'll be living it soon….
  
  

Bells and Whistles

• Presets. Many cameras come with "presets" that can be useful for various recurring situations -- sports, portraits, Eastern European espionage, etc.
  
  
• ISO settings. These replicate the various "speed ratings" of film, and set the light sensitivity of the camera's image sensor. Ideally, this lets you take pictures without a flash in low-light settings, and should auto-adjust.
  
  
• Anti-shake. Another term for image stabilization, this can be very, very nice on higher-end cameras. If you want to get really into it, optical image-stabilization is usually better than digital image-stabilization -- just as with zoom. Check the fine print in the spec sheet.
  
  

Summary

Generally speaking the digital camera market is hale, healthy and only getting better. You can get a lot of bang for your buck, and the fierce competition is ramping up the cool features while driving down the prices. Reminiscent, actually, of the great Scottish butter churn market of the early 1800s, when new advances to the barrel-style crank resulted in a boom of innovation and widespread distribution of -- well, that's a story for another time, I suppose.

Keep on Rocking in the Free World,

Dr. Samuel Centralia holds several dozen advanced degrees in computer technology, theoretical physics, applied mathematics, organic chemistry, dangerous explosives, situational ethics (medical and professional), and high-yield subsonic demolition. He has authored 20-odd groundbreaking nonfiction books, including "Shattered Motherboards, Shattered Lives," "Cloned: An Unauthorized Autobiography," and the worldwide bestseller, "Gigabyte!" He lives in a series of fortified underground bunkers with his dog, Copernicus.