When a sensor is advertised/sold as 1/2.3″ most people would think that is the diagonal of the sensor. Well it is NOT! It might even vary drastically between manufacturers.
For historical reasons the diameter of a fictitious Vidicon tube with the same active area is what is advertised!!
Unfortunately, it is even more confusing than that…
The same article also has a table, that I have expanded with two ratio columns. Some intermediate rows also added (data via wiki).
(And removed some columns to make it less confusing)
|Sensor||Asp||Width||Hight||x*Full||Factor adver. to real diag.|
Note that the actual sensor diagonal is approximately 2/3 (63% -72%) of the advertising figures!!
A 1/2 “sensor is thus effectively only about 1/3″ or 8mm
But to add to the confusion factors vary between models and manufacturers!
|Manufacturer / Model||Adver.||Width(mm)||Height(mm)||Real Diag.(mm)||Factor adver. to real diag|
|FujiFilm / F50,60,100,200||1/1.6″||8||6||10||0.63|
|FujiFilm / F30, 31||1/1.7″||7.44||5.58||9.3||0.62|
|FujiFilm / F900||1/2″||6.40||4.80||8.00||0.63|
|Sony / IMX220||1/2.3″||6.30||4.72||7.87||0,71|
So Sony’s sensor called 1/2.3″ is only 1.6% less in diagonal than what FujiFilm call 1/2″ !!!
Said otherwise Fuji could call Sony’s sensor a 1/2.03″, OR Sony could call Fuji’s 1/2.26″
So be REALLY careful when comparing sensor sizes that you look at the actual area in use!! – if you can get the correct info from the manufacturer!!!
As the factor used can vary with as much as 14% (matching 30% in area) it is easy to make wrong assumptions, and many sites do, assuming that e.g. all sensors called 1/2.3″ has the same actual size. There are NO reason to assume that – unfortunately…
See also this post on the Megapixel craze