Quote Originally Posted by Mikeh


[Daniel] - I've had two copies of the 18-55 IS and the 17-40, and never has the 18-55 "blown the 17-40L away". In fact, the 17-40L beats it. You can see the pics for yourself:


First, thank you for the correction -- you are right that the 18-55 IS doesn't really blow away the 17-40 -- it's only slightly better than the L. I should not have exaggerated.


Second, I was responding specifically to the OP's question about sharpness (i.e. contrast and resolution). I was not speaking about the overall performance of the lenses, such as color accuracy, flare, bokeh, transmissivity, etc.


Third, the test you linked to do not demonstrate superiority of the 17-40 in contrast or resolution. The 18-55 is sharper in the corners at all focal lengths, and in the center for most of the zoom range (18-28mm). The 17-40 is only sharper in the center at 35mm.


Fourth, your test photos are stopped down to f/6.3, almost two stops for the 18-55 at 18mm. The difference between the 17-40 and 18-55 are more striking when they are shot wide open. At f/6.3 they become more similar, which is why your pics show a smaller difference than other tests.


Fifth, the comparison you linked to is at hyperfocal distance, which makes it good for landscape photographers. However, my experience is that the strength of the 18-55 is in closer focus distances, such as for people and event photography. The contrast/resolution advantage of the 18-55 is clearer there.


Sixth, I agree that the 17-40 does not have the ugly color cast of the 18-55, but that is a separate issue from sharpness that the OP asked about. Furthermore, the color cast is easily corrected with white balance, or more optimally corrected with a color profile.


Finally, even if I was totally wrong and it is the 17-40, not 18-55, that has slightly higher resolution and contrast, then even then, such a difference is not a good reason to pay so much more for a lens. Maybe 20% more. Or even 50% more if you really need contrast. But not 440% more, which is what it takes to get the 17-40 over the 18-55. The advantages of the 17-40 are in other areas aside from contrast/resolution, such as build quality, focus, weather sealing, and much more. Those other reasons are what make it a good value.