Canon EOS EFS lens

Careful observation on Canon EFS lens has proved the reason for incompatibility on ordinary EOS body except Kiss models. The lens back of EFS is so short as to be hit by the mirror movement and the posterior lens element is protected by a rubber ring designed intentionally for safety in case of error. The most posterior glass comes back when the zooming operation of widest 18mm position. By setting some stopper at safer position not to interfere mirror movement and removing protection part, it might be possible to set on ordinary EOS body if vignetting does not exist, I do not feel any necessity to do that because of insufficient picture quality though lighter and smaller zoom system is attractive. My son deserted this first generation Kit standard zoom lens included in Kiss body. Probably, the lens designing engineer in Canon factory must have made incredible efforts to invite this EFS lens system inviting several design changes into existing EOS mounting system.