APS-C = a ton of advantages! | Bill Fortney

O.K. for all those folks that are sick of my talking about how happy I am with my Fuji X-System, this isn’t about that, well, maybe a little, but lots of cameras have APS-C size sensors and there are a number of reasons you should consider one!  If only as a back-up body! First, over the past four or five years the push was to go to “Full Frame” sensors, actually all sensors are full frame, (they occupy the entire frame no matter what their size!), what people mean is a sensor that is approx. the size of a 35mm film frame 36X24!  The push was because when they first became available they offered significantly better high ISO, low noise performance!  Not so much today.  The most recent top of APS-C size sensors have really been pushing the 35mm size sensors on noise, dropping the advantage to less than one f stop!!!   The other advantage for the 35mm size sensor was that lenses were their “actual” focal length, meaning super wide lenses, wet actually super wide.  Then the APS-C cameras got super wide lenses and super wide zooms, advantage gone.  The last big advantage was that depth-of-field was more shallow, thus leading to nicer Bokeh.  When the APS-C guys got very fast lenses, the APS-C depth-of-field more closely matched the 35mm sensors……

Source: billfortney.com