I purchased a canon ef 70-200mm f/4l (non-is) a few weeks ago and have been getting somewhat inconsistent results with the pictures. I have a Canon Rebel XTi (400D) and am shooting with no filters, no teleconverters, no extension tubes- only a lens hood. The following photos were all taken in RAW and converted in JPEGs, however, no post-processing was done in ACR. I just opened up the file in ACR and clicked "Open file" and saved it as a maximum JPEG. The photos were uploaded onto Freewebs and were not optimized for web. The photos uploaded look nearly identical/identical to the ones on my computer. All shots were taken using Partial Metering, and only the Central AF point was selected and the picture recomposed. These group of photos were taken about an hour before sunset. White balance was set to daylight. The embedded photos are all a 100%, 600 x 600 crop of the focal point and usually around the center frame. The link to the full, uncropped image is provided below the crop as a link. Pic 1 ISO 100, f/4, 70mm, 1/640s Full, uncropped image (4mb): http://www.freewebs.com/olumak/sample1.jpg Pic 2 ISO 100, f/4, 200mm, 1/800s http://www.freewebs.com/olumak/sample2.jpg Pic 3 ISO 100, f/4, 70mm, 1/400s http://www.freewebs.com/olumak/sample3.jpg Pic 4 ISO 400, f/4, 100mm, 1/160s http://www.freewebs.com/olumak/sample4.jpg Pic 5 ISO 100, f/4, 149mm, 1/320s http://www.freewebs.com/olumak/sample5.jpg This picture was taken indoors. The camera was rested on a coffee table and a 3 second countdown paired with an MLU was initiated. Pic 5 ISO 100, f/4, 200mm, 1/30s All of the above pictures I think are very sharp and are fine. But occasionally, I get pictures like these: These were taken during midday. Several shots were taken and all of them turned out this way. Pic 6 ISO 100, f/4, 200mm, 1/800s http://www.freewebs.com/olumak/fly.jpg Pic 7 ISO 100, f/4l, 200mm, 1/800s http://www.freewebs.com/olumak/leaf.jpg While this lens does produce nice results when it is working properly, I do not see too much of a difference when compared against the kit EF 17-55mm lens: Pic 8 ISO 100, f/5.6, 55mm, 1/200s (camera-mounted flash used) http://www.freewebs.com/olumak/emma.jpg I acknowledge the fact that this last picture used flash, while the other did not; but does it really make that much of a difference? Thanks.