Centuries ago, a young boy in Japan was preparing for a long journey. “You will need much drinking water,” said his master. “Construct a barrel that will catch the rain.”
After a quick run to his local Pagoda Depot for supplies, the boy built a large barrel, open at the top. When it rained, the barrel filled quickly.
“Good,” said the master. “Now pack it up.”
“But master,” the boy protested. “This barrel is much too big and heavy to take on my journey — it might not even qualify as carry-on! I need a much smaller, lighter container!”
“A wise observation,” said the master.
“And yet,” said the boy, “a smaller container means a smaller opening, and it won’t catch nearly as much rain.”
The master nodded again. “Excellent, my son,” he said. “Now you understand the trade-off between digital S.L.R. cameras and pocket cameras. The S.L.R. is big and heavy, but it has a huge sensor that collects much light; you can get sharp photos even at twilight. The pocket camera has a tiny sensor that’s blurry in low light, but at least you won’t slip a disk trying to carry it around.”
And for centuries, that’s how it stood. People could buy a big camera with a big sensor, or a tiny camera with a tiny sensor.
State of the Art - Sony’s Entry in the Big Sensor-Small Camera Race - NYTimes.com
I have taken up an interest in photography lately but never quite understood the difference between the big cameras (SLRs) and the pocket ones. I thought the story above is a good way of explaining it. For those who are wondering too.