Last August, I wrote about picture quality finally winning against macho marketing. In other words, it seemed Canon, Nikon and Sony were giving up the simplistic escalation: my camera has more pixels than yours, therefore it is better. In the P&S (Point & Shoot) category especially, the facts were that more pixels ended up producing mediocre pictures.
P&S cameras are the smaller (not necessarily simpler…) models you carry in your pocket and purse, as opposed to “superzooms”, bigger lenses with a wider range of focal length, or DSLR, bigger, heavier but also better, more flexible.
As discussed earlier, a look at DP Review’s excellent camera database will make the problem clearer: pixel density per cm² varies from 1.4 million, for high-end DSLRs, to 43 million for some P&S models. The smaller the pixel, the less photons received. The less photons per pixel, the less electrons they convert to in the sensor. This makes it harder to separate the “good” (picture) electrons from the “bad” (circuitry noise) ones. Everything else being equal, the result is higher pixel density means higher picture noise, that is worse picture quality, especially in low light when fewer photons fall on each sensor pixel.
(DP Review, arguably one of the 3 to 5 best photo sites on the Net, is now owned by Amazon. IMHO a smart move considering Amazon’s general reliance on user reviews to help its customers make good choices and, as a result, come back, and come back…) More
Finally, reason is about to prevail over marketing machismo. Specifically, Canon and Sony are coming up with more advanced cameras featuring less pixels.
Why? In these new cameras, less pixels translates into better pictures in low light. (You might want to refer back to two Monday Notes on digital photography: Pixels Size vs. Number and More on Sensors Digital Photography.)
So far, the selling argument has been more pixels equals better pictures. A higher number conveys an image, so to speak, of higher quality. This is not entirely untrue: it’s nice to have lots of pixels when you need to “crop”, to throw out a large fraction of the original image in order to concentrate on a key detail, a face for example. If you have enough pixels left in the “crop”, it will print or display with good detail.
But there is an important downside: for a given sensor size, more pixels means smaller pixels. In turn, this means each pixels will receive less light energy, less photons to be converted into electrons. The smaller number of electrons will have to “fight” against the background electrical noise in the sensor. The lower signal-to-noise ratio means lower quality pictures. This is particularly true in low-light situations where, to begin with, the number of incoming photons is smaller. More
In the (now waning) days of analog photography, much was made of which film was best: Kodak’s Kodachrome, Ektachrome, Fuji’s, Konica, Agfa, Ferrania… to name but a few of the old standards. Today, a similar debate goes on regarding the altogether simpler digital sensors. In the April 5th Monday Note #80, I took a first pass at the sensor size question, one that is, I believe, deliberately obscured by manufacturers. Showing their always flattering view of our intelligence, they peddle the number of pixels in the sensor, regardless of the size of those pixels. Never mind that (everything else being equal) pixel size makes the most important contribution to image quality.
Fortunately, the Web comes to the rescue with tutorials, charts and even calculators. Cambridge In Color features nice tutorials such as this one. A French company, DxO Labs, offers a sophisticated sensor rating site: You’ll see what I mean by sophisticated as the site provides numbers for color depth, dynamic range and low-light ISO. More
OMG, says the blogger, the next iPhone’s camera will have 3.2 million pixels instead of today’s measly 2 million! The blog entry gave me the final push for an occasional, meaning at irregular intervals, series of columns on digital photography. The idea is to find insights into what’s really going on in this very dynamic industry, to extract a few useful ideas from the flow of markitecture BS coming from hardware and software vendors on a daily basis. As you’ll see, these columns are intended for the ‘interested’ digital camera user and, on occasion, for the technophobe, but not for the pro – they use cameras to make money, not to have fun like we do. More