An amazing lens if one is aware of the limitations and nitrogens for it to work.
This lens is worthless without a macro flash as Canon MR or MT flash is a must.
It lacks autofocus, but it is not useful in this type of macro photography.
One can not be portrayed bumped objects than 1:1 so it can not be used for anything other than macro.
This lens is made only for macro photography and it does it well. Flash is a must even if the lens is an f2.8, it is not useful at lower than f8-f11 if you can not do with a focal depth of a few hundredths of a millimeter.