Tuesday, May 12, 2020

Truth in Advertising

I was doing some research on the Sony RX line of "luxury compact" digital point & shoot cameras and came across this dude's blog (which is a gold mine of film camera stuff, BTW).

I found that he reported the sensor size this way:
 "13.2 x 8.8, deceptive marketers (including Sony) call it a 1″ inch sensor, it’s actually 1/2″ wide or 0.52″ according to Sony."
Sensor size nomenclature can be confusing when you get away from the more photographically-oriented "Full Frame/35mm", which is the size of a 35mm negative (well, sort of...more on that later), and "APS-C", which is the size of an APS-C film exposure.

Smaller sensors are described with measurements like '1/2.5"' (in an iPhone XS), '1/2.3"' (most cheap P&S cameras), or '1/1.7"' (nicer P&S cameras). Most people ignore that as technical data buried in the instruction manual. If you ask someone what the size of the sensor was in the Android phone in their pocket or the Nikon CoolPix in their purse, they'd give you an answer measured in megapixels, not inches.

The disconnect comes when you run into the "luxury" or "enthusiast" end of the compact camera market, where the physical size of the 1" sensor in cameras like Sony's RX100 line or the Canon PowerShot G7/G9 is touted as a selling point.

Because the sensor itself is not physically an inch in any dimension. For that matter, a tiny 1/2.5" sensor isn't two fifths of an inch in any dimension either.

Small CCD/CMOS video sensors are labeled based on the size of video tube they replace. These tubes had a rectilinear imaging surface inside the cylindrical glass vacuum tube. Inside a 1" tube would be an imaging surface measuring 16mm diagonally, or a little less. When solid state sensors started replacing tubes forty years ago, they were labeled according to the tube they'd replace.

So to this day, a sensor 16mm (or a bit less) diagonally is still called a 1" sensor.

For that matter, "35mm" film is only 35mm if you measure from edge-to-edge, sprocket holes and all. "Full Frame/35mm" sensors are only about 29mm diagonally; there aren't any digital sprocket holes.

Just like we still "dial" and "hang up" our cell phones, even though phones with dials and handsets that you hang on the wall are a vanishing memory, digital imaging technology is still named after the analog technologies it supplanted.