I don't see the point of your reply about the article.You don't need the maths to work out how to use a Macro lens. It might be interesting for tech people but not to the orginal poster.
I have used the Nikon 60mm macro with great success but suggest the 105, 100 or 90mm lenses would be best. Unlike most lenses, the midrange macro lenses, from any maker will serve you well.
