Hi, and welcome to the TDP Forums!


First off, I firmly believe that there's no such thing as 'too much lens'. The quality of the lens has a much bigger impact on image quality than the camera body. Consider - the CMOS sensor in the T2i is the same as the sensor in the 60D, which costs a few hundred dollars more, and it's the same as the sensor in the 7D, which costs twice as much as the T2i.


However, one thing to consider about the 24-105mm lens is that it might not be wide enough for your needs, especially since you mention landscapes. Because of the 1.6x FOVCF (aka 'crop factor'), lenses on the T2i provide an equivalent field of view as 1.6x greater on full frame, like the film SLR you previously used. Good for the telephoto end, bad for the wide angle end - the 24-105mm gives the angle of view of 38mm on FF, which isn't even wide angle, and the tradeoff is a 168mm long end.


The weather resistance won't help you, as the T2i is not weather-sealed (the 7D is, and I use mine with a 24-105mm f/4L IS in the rain on a regular basis).


IMO, the best general purpose zoom for a 1.6x crop body is the EF-S 17-55mm f/2.8 IS USM. It's around the same cost as the 24-105mm, offers a true wide angle (27mm FF equivalent), and a fast f/2.8 aperture. The build quality is not as high as with an L lens, but the optical quality is definitely L-level. Another lens worth considering is theEF-S 15-85mm f/3.5-5.6 IS USM- it's got a broader zoom range and very good IQ, but is variable aperture and gets slow at anything other than the wide end, so performance will suffer in low light. It also suffers from more distortion at the wide end, resulting from it's broader zoom range.


The combination of the 17-55mm and a 70-200mm zoom is very versatile and will provide excellent IQ throughout the range. IS is a big help for still subjects, and the 70-200mm f/4L IS lens is also optically better than the non-IS version. Keep in mind that IS only helps with camera shake at the expense of shutter speed, meaning if your subject is moving IS is not as useful. At longer focal lengths, IS is of greater utility.


You mention wildlife, so I should say that 200mm is often not long enough. I use my 70-200mm f/2.8L IS II for wildlife only in the pre-dawn and post-sunset hours, where I absolutely need the f/2.8 aperture - in that case, I end up cropping a lot of the image away. In brighter light, I use the 100-400mm, often at 400mm. In case you haven't seen it, Canon is soon releasing a newEF 70-300mm f/4-5.6 IS L USMlens that provides some additional reach relative to the 70-200 series, at the cost of up to a stop of light compared to the 70-200mm f/4 lenses. As a side note, what you list as 'wild life (low light)' is one of the most challenging scenarios for a lens - wildlife usually means you need a long focal length, and low light means you need a fast aperture. The combination of long and fast means a supertelephoto lens (300mm f/2.8, 500mm f/4, etc.), and those start at over $4K.


Bottom line, I would recommend considering the EF-S 17-55mm lens. Personally, I have and use both the 17-55mm and the 24-105mm lenses on my 7D. I grab the 24-105mm when it looks like rain, or when I know I'll only be shooting outdoor shots of my toddler (where 24mm is wide enough, because she's less than 3' tall), or when I'm bringing several lenses on a photo outing, meaning I'll have the EF-S 10-22mm f/3.5-4.5 to cover the ultrawide to wide range. But for the most part I use the 17-55mm more frequently than the 24-105mm - it's the lens that stays on my camera when I'm at home, and if I could only pick one lens to take on a trip, the 17-55mm would be it.


Good luck with your decision!


--John