I’m pretty sure EF-S focal lengths are 35mm equivalent. They just project a smaller image circle and the rear element is closer to the sensor (so will likely crash the mirror on a full frame camera).
I just had a look at EF-S lenses at https://www.bhphotovideo.com. I didn't see anyone that used the 35 mm equivalent focal length in its name. For example, the first is called "Canon EF-S 24mm f/2.8 STM". The details mention "38.4mm (35mm Equivalent)", so 24 mm really is the real focal length, not the 35 mm equivalent one.
APS-C is a 1.6 crop. If you put a 24mm lens on a full frame 5D and a 24*1.6=38.4 mm lens on a APS-C 7D you will see the same angle of view.
The focal length numbers printed on an EF or an EF-s lens are the same thing for consistency. The crop factor isn’t included. So if you take a photo on a full frame 5D and also an APS-C 7D and crop accordingly to account for the difference in sensor size you get the same thing.
So what do the numbers printed on the lens correspond to? It’s hard to find but this canon page suggests it’s 35mm equivalent:
> The focal length numbers printed on an EF or an EF-s lens are the same thing for consistency. The crop factor isn’t included. So if you take a photo on a full frame 5D and also an APS-C 7D and crop accordingly to account for the difference in sensor size you get the same thing.
No, that seems to be a misunderstanding. The focal lengths on the lenses are the real focal lengths, not the 35mm-equivalent ones. For example, have a look at the EF-S 24mm f/2.8 STM [1] The name says it's focal length is 24mm; that 24mm is also printed on the lens. The description says "a 35mm equivalent focal length of 38mm". So clearly its 35mm-equivalent focal length is 35mm, and its real focal length is 24mm.
What that page indicates is the crop factor for each camera (i.e. the ratio of its sensor size to a 35 mm sensor, equal to the factor you have to multiply the real focal length with to get the 35mm-equivalent focal length). For the 7D, the table says that the 35mm-Equivalent Focal Length is "Approximately equivalent to 1.6 x the lens focal length". Let's apply that to our 24mm-lens above. 1.6 x 24mm = 38.4mm, which is essentially the same as the 35mm in the description (focal length specifications are not very precise anyways).
So it checks out: the number on the lens is the real focal length; to get the 35-mm equivalent focal length you can either look it up in the specifications or simply multiply with the crop factor.
I'm not very familiar with Canon, but as I presume you can put EF lenses on APS-C cameras (I know the equivalent of that works in the Nikon world). If you compare an EF 50mm lens and an EF-S 50mm lens on the same APS-C camera, you'll notice both have the same field of view. Because the focal lengths are the real focal lengths, they behave the same when placed on the same camera.
But if you compare an EF lens on a APS-C camera with that same lens on a full frame camera, you'll see that it has a wider field of view on the full frame camera (because the full frame camera has a sensor that's 1.6x the size).
When reading about focal lengths, always make sure to understand what reference the author uses; it's often not explicitly mentioned. For example, people often say a "normal" lens (i.e. a lens with a field of view that appears natural for us humans) is a 50mm lens. But that's only true for full frame sensors. For other sensors (or films) you need the equivalent: for APS-C (or Nikon DX) it's around 35mm, for medium formats it's 75mm or larger depending.
The confusion is that the true focal length and the full frame 35mm focal length are used interchangeably. The Canon link doesn’t make it clear other than to suggest it doesn’t really matter once you use 35 mm as your reference point.
