What really matters in a digital camera

David Pogue has bought a Canon PowerShot S95 pocket camera and writes that a major feature is its large sensor.

I love the huge light sensor that's inside an SLR. It can take sharp low-light shots without the flash. It can blur the background the way professionals do.

What I've always wanted is a little camera with a big sensor. Is that so hard? Apparently, yes. The problem is covering a rectangular sensor chip with a circle of light from the lens. Bigger sensor? You need a bigger camera. Those are the simple bylaws of physics.

The S95's sensor is 0.59 inches diagonally -- 88 percent more area than most pocket cameras' sensors. What this means:

The little S95, can take amazing, sharp pictures in low light without the flash. The designers have shrewdly dropped the ludicrous quest for more megapixels -- it has 10 megapixels, just right -- in favor of something that really matters, like better photos. So many times I've used it  for pictures at night, indoors, in shadow. Cathedrals, restaurants, parties. No, the results aren't as good as an SLR's -- it still manages to blur a shot, especially in very dark situations when the subject is moving -- but they're light-years better than any other pocket camera can do.

The bottom line is that just counting megapixels won't tell you everything about a camera's performance. Here's a bit more on this, from Digicamhelp:

The size of a camera sensor will have a big impact on the quality of your pictures. The lens gathers light and directs it towards the sensor, and the sensor records the light to create the image.

All things being equal, a larger sensor will receive more light than a smaller one, and produce better images. This is especially important in low light photography.

When light levels are low, a smaller sensor will generate a higher amount of noise, which will decrease the quality of the images. This is why the best low-light setups include a camera with a large sensor (usually a DSLR) and a lens with a large aperture.


In the compact world, most sensors are equivalent in size. Sensor size for compacts is calculated by measuring the sensors diagonally. The most common sizes are 1/2.5 (0.4) and 1/2.3 (0.43) inches. Pretty small by all accounts.

Manufacturers have started including larger sensors in some of their compacts. For instance, Canon’s s90 camera has a 1/1.7 (0.58) niches sensor. This represents a total area 37% larger than most comparable models, and yields much better low light pictures. Compact cameras like the Panasonic LX5 also sport larger sensors.

Something to consider if you're in the market.

Image: Relative sizes of digital camera sensors

Routine maintenance for your PC

Your PC needs some TLC every now and then. You can get a store to do it, for a fee. Staples, hoping to win new customers, will do it for free.

However, you can do it yourself, The New York Times reports. “Tools to do everything that Staples does are built into Windows 7,” said Ben Rudolph, Microsoft’s Windows PC Evangelist. “It’s not that hard to change your own oil.”

Here's the rundown.

It’s important to run antivirus software regularly. Microsoft offers MS Security Essentials, free antivirus software available from Microsoft.com. Mr. Ackerman recommends another free program, AVG Free (free.avg.com).

To avoid leaving any fragments of applications on the drive after you remove a program, use the application’s own removal tool, rather than just putting the program icon in the trash. If you don’t have the tool, do an Internet search for “[program name] removal tool.”

Defragment your hard drive. After extensive use, large programs tend to become “fragmented,” meaning that critical files are scattered across multiple sectors of a drive. It takes the computer extra time to find and assemble all the pieces needed to run the program. Defragmenting the drive will retrieve the files and place them closer together, speeding up the response time when you run the program.

The preinstalled Windows Disk Defragmenter tool, (search for “defragment” under the Start menu in Windows 7, or look for it under Programs>Accessories>System Tools in most older Windows machines) will defragment your hard drive, either manually, or automatically on a schedule you can customize.

Defragmenting a hard drive can take anywhere from a few minutes to a few hours depending on the size of the drive and how cluttered it is.

Most maintenance tools are easily found in Windows 7. Click on the small white flag in the bottom right of the screen to bring up the Action Center. If you haven’t installed antivirus software, you’ll be prompted to find such a program. You’re also given the option to back up your hard drive. 

Reviewing the new MacBook Air

I don't have an iPad, although I can see the day coming. I have a MacBook Pro, which I love and which is too new to replace. When that time comes, it may be that I can have both in the same machine.

Walt Mossberg, The Wall Street Journal's technology guru, has reviewed the new MacBook Air and found:

Some of the nicest, if little discussed, benefits of using an Apple iPad tablet are that it starts instantly, resumes where you left off, and has a long enough battery life that you aren't constantly fretting about running out of juice or looking for a place to plug it in. And it can do a lot of things for which people use laptops.

What if somebody designed an actual laptop that worked this way—you know, a computer with a real keyboard and a larger screen that could run traditional computer software and store more files than an iPad? And what if it was almost as light and portable as an iPad? Well, somebody has, and that somebody is Apple itself.

The new Air, he writes, comes to life almost instantly and yet has tremendous battery life.

In my harsh battery tests, I found the two new Air models almost matched Apple's battery claims, even with all power-saving features turned off, Wi-Fi kept on, the screen on maximum brightness and a continuous loop of music playing. The 11-inch model lasted four hours and 43 minutes, versus Apple's claim of up to five hours. The 13-inch model lasted six hours and 13 minutes, versus Apple's claim of up to seven hours.

It has less storage to make room for its better battery, he notes, a problem for someone needed to store big amounts of video, for example. And other things, like a DVD drive, have to be purchased separately.

"Overall," Mossberg writes, "Apple has done a nice job in making these new MacBook Airs feel more like iPads and iPhones without sacrificing their ability to work like regular computers."

Do you need a PowerMonkey?

I get occasional emails from an outfit I'm fond of -- Extreme Outfitters, your one stop shop for all things tactical. This is the online version of the Army Navy store in my town when I was growing up. It's the place for combat boots, knives, you name it.

This particular email advertised various power supplies, including the PowerMonkey-eXplorer, a portable solar charger for mobile phones, iPods, PDAs and more. I just don't know how I ever did without it. I mean the name alone ...


Here are some details:

From the heart of Africa to the Hardanger Glacier, the powermonkey-eXplorer portable charger has proved to be an invaluable piece of kit, providing essential power in the most remote locations. Incorporating the new solarmonkey solar charger, the powermonkey-eXplorer lets you charge wherever, whenever. 

The heart of Africa! I bet it even works in your cube, if you sit by a window. 

It gives you 96 hours of standby on your mobile, 40 hours on your iPod, 5 hours on your games console, 48 hours on your PDA and 6 hours on MP3/MP4 players. 

More:

Ultra compact, tough, powerful and Made for iPod approved, the powermonkey-eXplorer is water resistant and made from rubberised casing so can take whatever life throws at it, yet it remains the lightest, most versatile portable charger available today.

Seriously, if you go hiking or camping, or you're just on the road and needing some juice, it sounds ideal.

Create your own x-rays

Well,  not quite. But look what happens when you play around with Scotch tape. From Science News:

Forget fancy particle accelerators — a cheaper tool for emitting X-rays is right there in the office supply cabinet. Pulling back Scotch tape emits X-rays, the same high-energy light emanating from airport security scanners and the interiors of galaxy clusters, and scientists now have a better understanding of why.

Scientists have known since the dawn of 3M Scotch tape in the 1930s that pulling the adhesive emits blue light. But to discover that X-rays also fly out was perplexing because X-rays are a hundred thousand times more energetic than the chemical bonds holding the sticky side down.

Here's how it works.

Peeling tape separates positive and negative charges, creating an electric field. The field jump-starts free electrons in the neighborhood, accelerating them fast enough to emit X-ray photons. This bremsstrahlung radiation is like that created in the bellies of particle accelerators as they whip charged particles around near the speed of light.

They say it isn't harmful. Okay, you try it first. At atmospheric pressure, where air molecules bustle, the electrons quickly run into other particles before they can radiate X-rays. But one scientist imagines that soldiers and medical workers in the field could use a hand crank to peel off adhesives and create X-rays. The light is powerful enough to image a human finger.

Should you store your medical record online?

hIt's now possible to store all of you health information online, making it easily accessible anywhere, but only about four percent of people do. Many are afraid of the privacy implications, although these sites use the same technology as banks do to protect your information.

The Wall Street Journal has reviewed three of the most popular sites.

Google Health doesn't have many tools of its own to allow users to evaluate their health. Instead, it focuses on sharing your data with online applications that do such tasks, like the My Diabetes Health Assessment website, which evaluates users' risk of diabetes based on data from their health records.

Microsoft HealthVault, too, has a limited number of self-evaluation tools but connects to a wide variety of helpful services that can extract data from or import data to your profile.

You can accesss WebMD's Health Manager in two main ways: through its public site, WebMD.com, or through the sites of insurance companies and employers that are WebMD customers.

The Journal's assessment:

In the end, we found that each PHR offers a remarkable value for a free application, but none of the three emerged as a clear winner.

Microsoft HealthVault gets high marks for portability, but it has no features for printing. WebMD Health Manager has all of its health evaluation features built in, so you don't have to connect to external applications, but it lacks the ability to export information in some key industry formats. So does Google Health (it says it may add this later), but it does export data to online health applications.

One way to choose among the PHRs is by the applications that link to them. If you want to import data from LifeScan Inc.'s OneTouch glucose monitor into your PHR, for example, currently only HealthVault does that (Google may add this).

On the other hand, if your insurance company (yours or your employer's) is a WebMD customer, you may want to use Health Manager for its easy importing of all the health data your insurance company already has on you.

Also posted on my technology blog, Tell Your Doctor

Reach out and touch some one through Gmail

Does anyone know why we continue to pay hundreds of dollars for phone service?

Consider: Google launched an Internet-based calling service in August. Anyone with a U.S.-based Gmail account, compatible operating system, speakers and a microphone can make and receive phone calls from their inbox, Courtney Banks reports in The Wall Street Journal.

Gmail calling works best with a free Google Voice account, which assigns you a phone number that links to all your other lines – work, home or mobile. It acts like a personal switchboard operator, allowing you to decide which phone will ring when someone dials your Google number. Without Google Voice, you can only place outgoing calls through Gmail. 

"I could choose whether to answer the call on my computer or on my cell phone, and transfer calls between the two by pressing the star key," Ms. Banks writes. "For example, if I was chatting while walking into the house, I could switch the phone to my computer, and switch back if I had to leave. For technical reasons, call transfer only works for incoming calls."

Gmail calling with Google voice is versatile, because it can handle calls to your other phones. For the moment, it's also cheaper for certain types of calls. On Skype, computer-to-computer calls are free. But calling a phone costs 2.3 cents a minute to the U.S. and many other countries, or 2.99 a month for unlimited calls to the U.S. and Canada. On Gmail, all outgoing calls to U.S. and Canadian numbers and all incoming calls are free, through at least the end of the year. Charges for calls to international numbers cost from 2 cents a minute to landlines in much of Europe and Asia, to 99 cents a minute to Cuba.

Did anyone say free?

How cell phones can track illness

I've read about putting sensors on cell phones that would automatically tell a central computer that a biological or chemical terrorist attack was underway. Here's the same idea but in a more personal use.

Epidemiologists know that disease outbreaks change mobility patterns, but until now have been unable to track these patterns in any detail. So says Anmol Madan of the Massachusetts Institute of Technology and colleagues gave cellphones to 70 students in an undergraduate dormitory. The phones came with software that supplied the team with anonymous data on the students' movements, phone calls and text messages. The students also completed daily surveys on their mental and physical health.

A characteristic signature of illness emerged from the data, which was gathered over a 10-week period in early 2009. Students who came down with a fever or full-blown flu tended to move around less and make fewer calls late at night and early in the morning. When Madan trained software to hunt for this signature in the cellphone data, a daily check correctly identified flu victims 90 per cent of the time.

Two possible uses for this have emerged.

• The technique could be used to monitor the health status of individuals who live alone. Madan is developing a smartphone app that will alert a named contact, perhaps a relative or doctor, when a person's communication and movement patterns suggest that they are ill.
• Public health officials could also use the technique to spot emerging outbreaks of illness ahead of conventional detection systems, which today rely on reports from doctors and virus-testing labs. Similar experiments in larger groups and in different communities will have to be done first though.

And you don't have to make an appointment

Folks at the MIT Media Lab are playing around with a prototype of Netra, a system that can identify problems with a person's eyesight using only a smartphone, software, and inexpensive optical add-ons. The system could help people who can't afford or get access to full-service optometry.

Ramesh Raskar, an associate professor at the MIT Media Lab and the leader of the Camera Culture group there, said it dawned on him that the 300 dpi resolution on a smart phone screen made it the rival of expensive, specialized devices.

Raskar said the ubiquity of smartphones is a key part of what makes Netra attractive. While other systems have been proposed to provide optometry where it isn't currently available, those systems were limited by needing expensive equipment, or by being complex enough that they had to be used by an expert.

Similar hardware add-ons could transform smart phones into inexpensive sensor devices that could serve many medical and environmental needs.

Is this the post-PC era?

Here's a look at the media gadgets Americans own.

The technology research firm Gartner expects sales of 19.5 million units in 2010 for tablet devices like the iPad and Kindle and sees this going to a staggering 150 million units by 2013.