Originally posted by Kunzite Those figures are not sensor sizes, even though they're related. Just Google search for "sensor sizes" and you'll get plenty of results, relevant charts and explanations.

For example, 1/2.7" is ~5.37x4.04mm with a 6.72mm diagonal, and 1/1.8" is 7.20x5.35mm with a 9mm diagonal.

Well thanks for the explanation. I have followed it up and here, finally is the answer I was looking for, that is, the actual relevance of the numbers - they are in inches!?!?:

"- For small cameras, they use a bizarre fraction like “1/2.5 inches.” This is a diagonal measurement; divide 1 by 2.5, and you find out that the sensor is

actually 0.4 inches diagonally. In other words, a smaller denominator is better. For an S.L.R., though, sensor sizes are published as millimeters on a side, like “24 x 16 mm.” If you convert that to inches, and then calculate the diagonal, you find out that that’s 1.14 inches diagonally."

Larger sensors just use height and width in MM. Can't believe I am the only one who was puzzled by this.