Any opinions regarding the use of the canon 100mm 2.8 for potraits? Plan to embark in the 100 potraits of strangers and other than that lens I only have the canon 17-55mm. Will get an 85mm 1.8 in december still another question is how different are these lenses, I mean the 100 and 85 on a 7d ii? I know the 70 - 200 is great but way beyond my current budget. Apreciate any comments.