Q My friend told me that choosing a smaller picture size in my camera setting would result in cleaner, less noisy low-light photos. Is this true?
A Your friend is sort of right, but only in theory. Like film, a digital-camera sensor collects light. Unlike film, a camera sensor has to split that light into individual, discrete pixels. If you decrease the number of pixels that a sensor needs to create, it seems like more of the surface of the sensor could be devoted to each pixel. More surface area means more light absorption, which means better low-light photos. Here’s the thing: camera sensors are the number of megapixels of the photos they produce. Think of the pixels as little buckets: a 10-megapixel camera actually has 10 million of them, and they can’t change size. Some pro-grade cameras can group clusters of pixels to achieve the effect your friend is talking about. But the majority of cameras, when turned to a lower megapixel setting, will either capture a full-resolution image and re-scale it or simply use less of the sensor. Different image-size options are included to save storage space, not to improve image quality.