I shoot mostly sports photography outdoors so I have a 70 - 200 2.8 L (Canon) That is the only lense I have..........I have kids and am wanting to do more portrait syle photography of them, both outdoors and in studio. What would be a good all around lense to get for that type of photography? (canon) Keep in mind, I,m not a "pro" photographer so keep it simple for me please.