EF17-40L, just curious how it works.

[toddb]

I received my first L lens this week from B&H, the EF17-40L. I made the mistake of trying to compare it to my 28-135IS and 50F1.8. I was limited to the indoors because I was sick, but couldn't really make out any remarkable image quality differences. I decided I was just going to drive myself crazy if I kept at it. I'll probably see the real difference in landscapes which is why I got it and it rugged durability. Being my first L, I was impressed with the build quality. I have also read that ultra zoom lens are never super sharp just because of it's construction of getting such a wide angle.

Here is my question. The back of the len where it connects to the camera, when you zoom, that piece of glass moves farther away from the camera body. Is this pretty much the same as a built in teleconveter? I've never seen that back part move and I just thought that was interesting.

[griff2]

I'll answer you first question. I've compared the 17-40 f/4L to both the 18-55 kit and the nifty fifty. Compared to the kit it's much sharper with much more detail, much greater contrast, and vastly superior colour rendition. Compared to the 50 1.8 sharpness is about the same, but, again, there's much more detail, and colour rendition is, again, far superior. As for your second question, a Google search, or a search on one of the many Canon websites may help there.

[GyRob]

i just did that test myself shooting a ruler and agree, but the fifty came out a tad sharper and also beat my 85 f1.8 also my 300F4 all tripod shots around f8 and selftimer with the 300. not one is what i call really Sharp and makes me wonder what people do who dont have a computer to sharpen them.
i know people rave about canon but just from the camera there not that good.