I don't know, Donald... your latest results looked pretty swishy to me... ;-) I'm still expecting a detailed lens report. 100-400mm f/4.5-5.6L IS $1,349.95 7.4"X3.6" 3.00 lb 70-200mm f/2.8L IS $1,619.95 7.7"X3.4" 3.5 lb EF 75-300mm f/4.0-5.6 IS $ 399.95 5-7/16"X3-1/8" 23.5 Oz Interesting... the faster 200mm is a little bit thinner than the slower 400mm (which I guess isn't a surprise). But the 400mm actually has a shorter barrel than the 200mm. [The folks just love it when I compare sizes!] I can see why this discussion would make anyone's head hurt. There is very little to tell from the Marketing literature. Do some of the magazines still do lens reviews with numbers? Having a trusted recommendation is still the best, but I've gotten into too much trouble by recommending things. [The best thing that helped my sharpness, BTW, was a tripod.]