The DA50-200 is a nice small lens, but its macro feature is not that great, only at about 0.24x mag ratio. You'd better go with a Tamron 70-300 LD macro or Sigma 70-300 APO macro (both have 0.5x mag ratio for macro). These are cheaper too, but of course they are bigger and heavier ...
And of course a dedicated macro lens would give you a lot better results for macros