I am confused about Crop sensor ratios and their impact on EF-S Lenses

[Buckster]

Since I use both FF and Crop bodies, it's important to me that I understand what's what. That said, it's also important to clarify it because you really need to get a handle on it, even if you don't personally need, so that you can STOP giving out bad information to others. Now follow along:

If I'm shooting with a FF body and a 16-35mm lens at 16mm, and then I want to switch to a crop body and get the same field of view for essentially the same composition, I have to use the 10-22mm lens on that crop body at 10mm. I have to do that because the 10-22mm lens on a CROP body = a field of view equivalent to the lens' spec of 10-22mm TIMES 1.6, which is 16-35mm, which is the field of view I'm looking for.

The fact that the EFs 10-22mm won't fit the FF body is irrelevant. ALL LENSES' focal length in mm, whether it's EF, EFs, FD or whatever, ALL are tuned to FF bodies as a base for field of view. ANY LENS you put on a CROP body means a CROP of 1.6x has to be factored in.