Britain’s new Highway Code. Updated but outdated – a victim of the measurement muddle

The new Highway Code is an example of the consequences of the Britain’s measurement system muddle. Its mixture of units from the imperial and metric systems brings confusion, when clarity should be a foremost requirement. The UK Metric Association (UKMA) has looked forward to the completion of the metric changeover, and produced a simplified, metric version of the Highway Code to illustrate the clarity that one system makes possible. (Press release issued on 27 September 2007.) Continue reading “Britain’s new Highway Code. Updated but outdated – a victim of the measurement muddle”

The Four Thirds system

In response to a misconception voiced in another article,, it may surprise some readers to learn that the image sensors in Four Thirds digital cameras do not have a diagonal size of four thirds of an inch.

[Article by Martin Ward]

The naming of the Four Thirds camera system is a good example of a practice that is often used when a manufacturer wants to hide the true size of a product from the consumer. Namely, an obscure or deceptive imperial measuring convention is used instead of the original metric design size. The image sensors in Four Thirds cameras are actually 18 mm x 13.5 mm (22.5 mm diagonal), with an imaging area of 17.3 mm x 13.0 mm (21.6 mm diagonal) – quite a lot smaller than a diagonal size of four-thirds of an inch (33.9 mm), and significantly smaller than the 22.5 x 15.0 mm and 23.6 mm x 15.8 mm sensors used in the equivalent cameras of competitors Canon and Nikon.

The practice of describing image sensors in this deceptive manner continues from the days when all image sensors consisted of vacuum tubes and were described by the physical diameter of the glass tube, which was always larger than the “diameter” of the image sensor inside. Thus the imaging area of a Four Thirds camera sensor (17.3 mm x 13 mm) is the same as the imaging area of a hypothetical vacuum image-sensing tube of 4/3 inch diameter.

As with LCD and plasma TVs, technology has changed beyond the point where it makes any sense to continue using the old measuring conventions. It would be far more useful to modern consumers to describe the sizes of TV screens and camera image sensors in terms of width x height in standard metric units, than in terms of the diameters of hypothetical vacuum tubes, especially when these products now come in different aspect ratios. But, as is often the case, the needs of consumers do not always coincide with those of the marketing departments of manufacturers.

Further information on the Four Thirds system can be found at

Metric and the decline of UK manufacturing industry

Metric Views’ attention has been drawn to an article recently posted on the “Weekly Gripe”. This links the decline in the 1980’s of the UK’s engineering and manufacturing industries to their failure to embrace metrication in the decade before.

Continue reading “Metric and the decline of UK manufacturing industry”

No return to pounds and ounces

Today’s announcement by the European Commission that it is to propose that “supplementary indications” (such as lbs and oz) should be allowed indefinitely does NOT mean that traders can go back to weighing and pricing in imperial measures – so says the UK Metric Association (UKMA). [Press release issued on 11 September.]

Continue reading “No return to pounds and ounces”