Making sense of compact camera sensor sizes

[AdamJ]

I've never really been interested in compact cameras but now that the good ones are getting bigger sensors, I'd like to be a bit more informed about them.

Please would someone explain to me what 1/1.5" means. I know that it doesn't mean the sensor is 1" x 1.5" because that would make it fractionally larger than full-frame.

I think I'm right in believing that it indicates the ratio of height and width, but how does it tell me what actual size the sensor is. Why don't the manufacturers simply state the sensor's height and width in mm so that simpletons like me can understand?

[PeterJ]

I was wondering about that a while ago as well, the terms are confusing because the inch isn't really an inch. The following Wikipedia article explains it and has a table of the common sizes:

http://en.wikipedia.org/wiki/Image_sensor_format#Compact_digital_camera_formats

[AdamJ]

Many thanks for the link, Peter.

Quote from Wikipedia:

"The sensor sizes of many compact digital cameras are expressed in terms of the non-standardized "inch" system, as approximately 1.5 times the length of the diagonal of the sensor. This goes back to the way image sizes of early video cameras were expressed in terms of the outside diameter of the glass envelope of the video camera tube."

As a unit of measurement for today's compact camera sensors, this seems completely bonkers! It only confirms the validity of my question: why can't they just state the height and width in mm!?

[neuroanatomist]

...why can't they just state the height and width in mm!?

Because then consumers could easily compare across models and brands.  Goodness knows, we certainly wouldn't want that...  </sarcasm>

In many industries, specifications are given in non-standard units or relative to brand-specific benchmarks to make comparisons more difficult for consumers.  Marketing departments just want you to believe, "Ours is better - trust us!"

[Bennymiata]

This courtesy of DP Review