Yes, yes, I know a similar question has been asked a number of times before, but I am kind of well...lost. The short version of my problem is that I am not entirely happy with my lens set, in particular my "walkaround" lens - I'm looking for something to replace it, but there seems to be no single "obvious" pick, unless I am missing something. Am I? The long version: Well, I have a 40D. I am contemplating switching to full frame camera in a year or so - meaning that I am primarily considering either an (relatively) inexpensive EF-S (or 3rd party lens designed for 1.6 crop cameras), or a (possibly more expensive) lens that I could continue using if I switch to full-frame. Budget is not really an issue...well, within reasonable limits, of course - no 1200mm lens for me. The lenses I have are: Canon EF-S 10-22 -Use it a lot for landscapes, also some other stuff. Really happy with it, despite some CA problems it has, but many of my best pictures have been taken with this one. If I switch to full frame, I would sell this one with the 40D and get a 16-35 or 17-40 instead. No problems there. Canon EF-S 17-85 - the "kit" lens I bought with the camera - more about this one later. Canon EF 50mm f1.8 - Well, everyone knows this one. Canon EF-S 60 macro - In hindsight, buying this one was a mistake - I should have taken the 100mm instead, but I will get that eventually, regardless of whether I switch to full-frame or not. No issues there. Canon 70-200 IS L - What to say .. I love it, and of course there are no problems there if I switch to full-frame. Vivitar 800mm f/8 - A 40 year old manual lens - interesting, but irrelevant to my current problem Now, here is the problem: Sometimes I like going for a walk with just my camera and one lens - I typically do this if I know beforehand I will not be taking landscape pictures, or that I will not need a wide angle. So, in my case, that means the 17-85. What happens is that I frequently discover that my "walkaround" lens is not ideal - it is not long enough - I am bumping into the 85mm end far more often than the 17mm one. An ideal/reasonable "walkaround" lens for me would be something like 20-135mm, f4, but of course no such thing exists, so I have to compromise. Also, I am not 100% happy with the image quality when using the 17-85, compared to what I get with my other lenses. So, what options do I have? I could get something like the 18-200 (new canon lens or the Sigma one, or even the recently announced 18-270 from..uh, Tamron, I think, but I don't need all that length, and I'm afraid that the compromises that have been made in the design of those lenses would negatively affect what I really need - I doubt the image quality is any better than what I get with my 17-85. Also, none of those lenses would be usable on a full-frame camera. A second option would be the 28-135, which is light and convenient as a walkaround lens, with IS, but probably not wide enough on the 40D, and not long enough on a full-frame. A third option would be the 28-300 L, but it is not really wide enough on my 40D, but pretty much ideal on a full-frame - well, if it wasn't for the weight. A bit heavy for a walkaround lens. The fourth option I was considering was the 24-105 L IS lens - which would give me the extra length og my 40D, but on a full frame I would be back in the same situation as I am in now with my 17-85 ... although with a higher quality lens. The final option is just to admit I will never get a "perfect" walkaround lens, and just resign myself having to carry my bag around, but even in that case I still would need a replacement for the 17-85 when/if I go full-frame. So, my question - are there any factors I am missing - any options or 3rd party lenses worth considering?