Leica D-Lux, Panasonic LX100: Mystery of the 4/3 sensor that isn't quite
The new Leica D-Lux has a 4/3 sensor and a 10.9-34mm zoom lens. Since a 4/3 sensor has a crop factor of 2, this lens would normally equate to 22-68mm. But it doesn't. The manufacturer claims that the lens is actually 24-75. This puzzled me at first. A 4/3 sensor has always had a crop factor of 2, so the figures do not add up.
The answer seems to be that this camera doesn't quite use all the sensor area because of the variable aspect ratio function. The effective area is thus marginally less than the normal 18x13.5mm of a 4/3 sensor and this results in a crop factor of around 2.2 — hence the 24-75mm lens. All this makes hardly any difference to the performance of the camera, it's just interesting to know.