I dont know if someone can help me or not. I have a canon 50d.. and I have a hard time getting it to focus on my two children. It seems to always focus one child and not the other. I am sure this is user error so I am not sure how to fix it. as you can see with the picture one subject is clearly in focus and the other is not. For these photos I was using a canon 50mm lens. looking for any advice.