In article <4b6n9q$593@lll-winken.llnl.gov>, bkesser@llnl.gov says...
>Correct me if I am wrong, but I thought that f3.5 was a 1/2 stop slower
>than f2.8, not 2/3 stop slower.

Nope. Sorry. (And I, too, am a fan of the E 75-150mm, but I find the 70-210mm F4 E [and early AF] to be close enough in performance
to justify the extra size and weight in return for the extra length.)
Hope this helps.