[JJ_SO]

This is an APS-C lens with an APS-C image circle - you may argue with 1.55x or 1.6x there but that's about it.

 

1.6 to 1.34! The lens also covers the new Sigma Foveon APS-H. 

 

You were referring to the lens, not to the limits or crop factor of Canon APS-C size. Ignoring the speed of the lens, which is the reason for it's size, price and weight is the result of this silly equivalence games.

 

You also would not "equivalent" a remote controlled model racing car going up to 100 km/h to be 2000 km/h fast because the genuine "FF"-car model is 20 times bigger. 100 km/h = 100 km/h.

 

Also, FF is just one of many sensor sizes. Given the amount of phone cameras and their sensor sizes, there's no reason to declare FF to a reference. Not many of today's daily camera users ever took pictures on film - or full frame cameras, which are NOT the center of photographic world anymore. So, I think it's better to use the true specifications and not equivalence numbers.