Part of the reason for these tests is that I do not (yet) have the
experience to differentiate between bad technique and inferior
equipment... so as I consider a new lens, I want to measure the quality
of the two kit lenses as a reference point. There are a lot of strong
opinions out there with respect to lens quality. For example, I'm
interested in the EF 28-135mm F/3.5-5.6 IS USM lens. Research is all
over the map: "Perfect walk-around lens." "Way too soft." "IS is a
life-saver." "IS is not worth the money." And my personal favorite:
"Watch out for bad copies." Bad copies? There goes some more hair...

I guess there's no substitute for just plunking down the $$$ and trying
it out.

Or, you can use modulation transfer curves and make decisions based on how
you will most often use a particular lens:

http://www.usa.canon.com/consumer/co...mode lid=7445

By the way, the sharpness freaks can lead one astray. I have run tests
between two similar Canon zoom lenses, one of which was L-glass, and was
underwhelmed with the difference in sharpness. It was definitely there ...
I could see it; but honestly the difference was modest. Just me.

I'm not saying that L-glass is not worth it, by the way. Auto-focus
acquisition time and ruggedness are certainly worth having and paying for if
one has deep pockets or is a pro.