EF 70-200mm f/2.8L USM or EF 70-200mm f/4L IS USM.One one hand the 2.8 will allow more light in and a faster speed with lower iso.The f4 IS has IS which helps to keep the shakes away but not sure how much it'll help in night shots.My test shots would be like at local S league games which the only available light is the spotlights.Advice please thanks.And please i don't have the money for the 2.8 IS.