Quote Originally Posted by saturnia
Another issue is its famous dust problem. At least my lens collected such a layer of dust behind its front lens within one year that I'll send it better to Canon's service. Some dust specles do not affact image quality but from that much I expect to get closer to some visible effects (flares or at least loss of fastness).

I owned this lens for some time as well. I was very impressed with the pictures it took, but mine was a dust magnet as well. I know the dust doesn't really degrade the images it would take, but I'm far too OCD about my gear and it bothered me, so I actually cleaned the lens a couple of times myself. This YouTube video (http://www.youtube.com/watch?v=tOZRN2mxajk) gives a great little tutorial of how to do it. I used toothpicks to pull up the ring around the lens, since the wood isn't hard enough to scratch the lens.I eventually ended up selling the lens when I bought a 5DII and the 7D became my backup/telephoto camera.


Quote Originally Posted by <span>Gustaftoni
Well, if that squirrel is a worst case sample, I think I'll get the 100-400 as soon as I can.

A couple things you might want to be aware of with the 100-400mm: The lens is quite a bit larger than the others you probably have experience with. It's not an easy lens to take on hiking trips, camping, or anywhere where space or weight become issues. I know some might argue this with me, and really it's all personal preference, but I disliked the push/pull mechanism of this lens. It's also not weather-sealed, unlike most current L glass, so depending on what situations you're considering using the lens in, this is also a factor to keep in mind.


I own a 70-200 f/4 IS and am quite happy with it. I've used it for landscapes, people, flowers, etc. I've never used the non-IS version, but from what I understand the upgrade to the IS version is worth the significant increase in price. IS on a telephoto lens is just too valuable and I understand the build quality and image quality is better as well. 200mm might be a little on the short side for you, but for the same price as the 100-400mm you can buy the 70-200mm f/4 IS and the 1.4x teleconverter. This would result in a 98-280mm f/5.6, and on your 7D would actually be 157-448mm. Still not the potential 160-640mm of the 100-400mm, but in a lighter, more versatile package. There's so many pixels on the 7D, cropping is definitely an option.


If it's not too late, for you I might recommend either the EF-S 17-55mm f/2.8 IS or the EF 24-70mm f/2.8 coupled with the EF 70-200mm f/4 IS + 1.4x teleconverter.