In article , Neil
wrote:

I think some definitions have changed from the days of film. The
digital idea of "full frame" makes no sense in the physical size of
film frames. So, I take it to mean that it retains the full
_perspective_ of a lens rather than the cropped view that an APS-C
sensor would normally yield.

Fullframe still means 35mm film sized frames.

If so, what is the "frame" in a digital camera? It certainly is not an
ASP-C sensor.

Full frame is 36x24mm.* FF digital sensors are typically within less
than a mm of that size.* The Sony a7 III for example is 35.6 x 23.8mm.

Digital cameras can employ any size of course and APS-C is a very good
compromise in getting lens sizes down while rendering high quality
results (though that's not why it was introduced).

You have, again, misunderstood my comment. An APS-C sensor (and many
other digital sensors) is NOT EVEN CLOSE to the "35mm full-frame" size.

not true. aps-c is approximately half the area of full frame, equating
to a one stop difference.

nikon dx: 24x16mm
nikon fx: 24x36mm

smartphone cameras are what's 'not even close'.

There is NO correlation between them. Ergo, the "full frame" reference
is to something other than sensor size.

https://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Sensor_sizes_overlaid_inside.svg/1200px-Sensor_sizes_overlaid_inside.svg.png

if it's something other than sensor size, why show a link that only
shows sensor size?

the term full frame dates back to the 1950s, long before digital, which
used half frame to double the number of exposures on a roll of film.

https://www.olympus-global.com/techn...roducts/pen/pe
n/
The Pen is a half-frame film camera that uses 35mm film. The
first-generation Olympus Pen camera appeared in 1959.