They look like some type of recycled plastic material. looking for my (Dutch to English) translator button to read the description. Fortunately, I do not do much tropical travel, but moisture is everywhere.
@D.Sim - did your sister ever figure out you were the "borrower"? I have two sisters and that would have been an interesting "discussion".
@ D.Sim & xROELOFx - thanks for the feedback. More things to consider in the process. Leaning toward the 300 due to size and IS. Fortunately, not a pressing timeline, so I can change my mind a few more times.
@ xROELOFx & Trumpet - this is the type of real life experience I was looking for. Shooting on a crop body for now (1D some day). I will mull over the pros (many) and cons (few) of each. weight seems to be a big differentiator.
do not think either will be a bad choice...sort of like splitting hairs on a bald man.
@ Paul - I am using the 7D for sports and wildlife, so I am excited about the reach and flexibility with extenders. AF and fps are as good as I can get...will migrate to a 1D system (hopefully, some day, budget allowing). This is just a passionate hobby for me, do not have the raw artistic skills you pros have, (yet?).
@Flake - Thanks for the third party lens perspective. I have been one dimensional (Canon only) for so long that was not part of my consideration. I love the focal range the Sigma offers, as I would be using extenders to get the reach I want for birding (on top of the 1.6 the 7D provides). As far as the reality check of who is looking at me or showing off, it would be too little, too late (past that stage in life).
Will definitely look at the Sigma, but what are your thoughts about the IQ of an "older" 400 (non-IS) versus a relatively "younger" 300?