BSI image sensor technology set to change how cameras capture

Some camera manufacturers have developed a relatively new backside illumination, or BSI, sensor that keeps the surface of the sensor clear of all electronic parts, a recent presentation delivered at the Image Sensors Europe conference, in London, revealed.

The technology may dramatically improve digital photos and video on a host of products, including basic cameras, SLRs, camcorders, and even smart phones. In fact, a number of manufacturers are banking on BSI, hoping to make it a growing trend over the next several years, according to CNET.

Here's the idea: Imagine if you wore eyeglasses that were crisscrossed with braces that kept the lenses in place. You'd be able to see, but some of what ought to come through the lenses would be obstructed, and the overall image would be dimmer. In a way, most camera imaging sensors included in cameras and camcorders do the same thing; they include small electronic parts that block some of the light coming through your camera lens. BSI is meant to correct this.

Sony, which has been a leader in BSI technology and has included its Exmor R back-illuminated CMOS sensor in a number of its imaging products since 2009, also manufactures sensors for other companies such as Nikon, which includes BSI sensors in its SLRs. According to the presentation, such BSI sensors are said to perform better in low-light situations, which are often challenging environments for conventional image sensors in point-and-shoot cameras and particularly smart phones. This may be why the iPhone 4, which includes a BSI sensor, shoots better images than the iPhone 3Gs. In fact, there are rumors that a new-and-improved Sony Exmor R BSI sensor will be built into the next version of the iPhone.

Here at Consumer Reports, where we test imaging devices such as camcorders in low-light situations, we haven't found much of a difference: Most devices that included BSI sensors haven't shown significantly better low-light performance compared with devices that had conventionally constructed sensors.

Still, since many factors, including lens quality, can affect low-light performance, it's difficult to determine to what extent this finding reflects on BSI sensors versus other design factors. But we'll be monitoring new developments in this technology to see if we notice any significant changes in low-light performance.

—Terry Sullivan