david_ammer

<p>I used to own the 17-40 and upgraded to the 16-35 for IS. I remember the issue you're describing on the 17-40, but I now always remove the protector (UV) when adding polarizer etc and I typically don't stack any further than that...at any rate I would think a set of 82mm filters and a 77mm>82mm step-up ring would solve the problem more cost-effectively than the lens upgrade though, especially if you can get a few bucks back for your used 77mm filters.</p>

<p>I second the suggestion of getting one that can also serve as an eTTL master; my ST-E2 died after less than two years of pretty minimal use.</p>

<p>I had a similar experience and called the rebate center (phone number at the top of the rebate application form). Upon their explanation of the similarly missing necessary information, I re-submitted the documents via email and eventually received the rebate.</p>

<p>I may be mistaken, but I recall the built-in hood on the Mk I being considerably shorter than the detachable hood of the Mk II which leads me to wonder if it is less helpful and/or if the larger one contributes to more vignetting.</p> <p>Not a significant sample size, but FWIW the only Mk I I've used was noticeably less sharp than the single Mk II I previously owned, and had considerably more dust inside from its longer service life.</p>