I'm looking to purchase a lens specifically for shooting outdoors with families and kids. I have the 50mm 1.8 that I love, but I just feel it's not very convenient without a zoom for what I want to use it for (kids moving around a lot since I don't want to do all posed shots). I have the 70-300mm 4-5.6 but I would prefer to use something lighter and with a fixed f-stop. I also feel that lens isn't very sharp unless i'm shooting in the shadows...is that normal for it?
The thing is, I don't know what focal length I need/want for that type of photography :\
Any suggestions on a sharp zoom lens for shooting kids/families (1-4people at a time) outdoors? (in shadows and direct sunlight during sunset or sunrise; just thought i'd mention this because some of the lenses i've had create a blurry halo around the subject when shot in direct sunlight even though it's soft light)