Canon EF-S to EF converter?

[Big Mike]

They're generally not as good quality as EF lenses of the same focal length and I'm pretty sure that there are no "L" desginated EF-S lenses.

I don't agree with that. The EF-S 10-22mm is at or near L quality and the EF-S 17-55mm F2.8 IS, surely has L level image quality.
The rest of the EF-S lenses aren't up to that quality, but you could say the same thing about many of the EF lenses as well.

As mentioned, Canon just doesn't give the L to EF-S lenses, irregardless of quality.

 

[Village Idiot]

They're generally not as good quality as EF lenses of the same focal length and I'm pretty sure that there are no "L" desginated EF-S lenses.

I don't agree with that. The EF-S 10-22mm is at or near L quality and the EF-S 17-55mm F2.8 IS, surely has L level image quality.
The rest of the EF-S lenses aren't up to that quality, but you could say the same thing about many of the EF lenses as well.

As mentioned, Canon just doesn't give the L to EF-S lenses, irregardless of quality.

^^