EF 24-105mm f/4L IS USM
This lens is my EF 24-105mm f/4L IS USM (L stands for luxury, IS stands for image stabilization, USM stands for ultra sonic motor), actually I like this lens much because this is general zoom lens that make me easily to take photo in many conditions. Flexibility is important for general zoom lens, this lens has IS which can prevent hand shake. IS helped me in many conditions, for low light conditions I still can shot without tripod….. for me bring a “burden” tripod is only worthed if I want to take a landscape photo or group photo. As a general zoom lens, this lens also has long focal length range, I can capture use focal length equal 24mm to 105mm. Compare with EF 24-70mm f/2.8L USM, this lens is lighter & cheaper; It also has longer focal length range and image stabilization, but maximal aperture only 4 (not 2.8).
As a zoom lens there is something that you can’t get. You can’t get sharpness as good as fixed lens, that’s the weakness of zoom lens. You can choose what is your priority: Flexibility or Sharpness; when I started learning photography I choose flexibility, but in the end I choose sharpness. That’s why in the end I change this lens with a fixed lens EF 35mm f/1.4L USM.
More detail can be seen here: http://www.the-digital-picture.com/Reviews/Canon-EF-24-105mm-f-4-L-IS-USM-Lens-Review.aspx