>>4237372>>4237376If you want to go macro without buying another objective, you could get macro rings that will let you get closer with the one you already have, they're pretty cheap, and considering the alternative is another lens, they're practically pennies.
I'll also recommend closing the aperture a little bit to gain more depth, the closer you get to something, the shallower the depth of field, meaning that a smaller bit of what you're photographing is in focus, pic related.