After searching through this forum and extensive "googling", I haven't found the answer.

When a lens is built specifically for APS-C sensors (Canon or Sony), are they useable on the NEX-FS100 without vignetting or loss of image at the border of the frame?

I know the 'crop factor' is approx 1.5 on the FS-100...
I also know Canon

Thanks

All of my Nikon APS-C lenses do just fine on the FS-100. I doubt Canon lenses are any different in the size of the image circle.

I've used the APS-C kit lens that came with my 7D and it was fine. It's the only APS-C lens I have but I'd be reasonably confident they'd all work ok.

If you're using EOS lenses you might check Metabones. I seem to remember something about the adapter not working with some of the Canon S lenses.

Little need to worry about vignetting -- you lose the corners with HD video anyway.