Leaving the down-sizing issue aside, using random lens owner pictures to compare optical quality of lenses is just not practical. There are too many factors affecting the picture quality. For example, factors like camera shaking, subject motion, quality of light and the subject itself vary so much from picture to picture such that these variations tend to by many factors mask off the objective differences between modern lenses, which are getting diminishingly small. The objective optical quality of a lens puts a limit on the potential of the quality of pictures taken using the lens. Often the quality of pictures realized are far below the potential. To compare the true potential of lenses, factors that affecting the picture quality besides the lens itself must be under control to have meaningful result.