A couple posting ago I went on a rant about how people in the photo-forums have nothing better to do than squawk about something they know little to nothing about. Mainly, that lenses have properties that influence image quality that are obvious (to them). I'm thinking of the flame wars about Nikon vs Canon sharpness. I'm thinking about the Leica crowd who fervently believe their images are better than anyone else's because Leica lenses are (somehow) better. I'm thinking of the heavy Sigma lens bashing that goes on. I'm thinking of the folks who pick over potentially unobservable details between one Canon zoom over another. I'm thinking of the folks who "test" lenses and then pontificate over their findings.
OK. So I too am pontificating. Here's my proof. So maybe I'm not exactly pontificating, rather just sharing potentially useful information.
I have once again proven to myself (if no one else) that lenses, by and large, are not the limiting factor in image resolution. From my observations, the sensor is the limiting factor.
Look at the test of four lenses and look for the smallest group of lines that can be resolved. Compare results within specific focal lengths. Look at the influence (or, really, non-influence) of aperture on resolution. Then think about what these observations mean.
If you're being truthful with yourself, you'll realize, as I have, that lens resolution is really sensor resolution in the case of modern AF optical systems. There is no way of getting more resolution into a file than this.
So why do folks go on and on about which lens is better than another? They say "resolution" in many cases, but what people may really be referring to are other dimensions. Perhaps build quality? Perhaps how a lens "feels" in the hand? Or, what I really suspect is true in a large number of cases, is how people can impress complete strangers with their ability to spend large sums of money.
If you want to make wonderful images, buy a lens. Just about any lens. If you want to impress folks, I'm sure you can find a way to spend a lot of money to achieve you goals.
The following are 100% center crops from a 5D MkII Canon full frame DSLR. +1 EV CR2 originals were then converted using #3 Sharpness in DPP. The image style was set to "Standard". No other manipulations were made to the output.
Click on this image, mouse over the image, click again and you can observe the file at full resolution.