on 03.03.03 13:27, J. C. O'Connell at [EMAIL PROTECTED] wrote: > most "normal" ( non-macro ) lenses are > optimized for a single focus distance, or > in the case of IF lenses, a range of distances. > By adding a ext. tube and going closer than designed > you will usually degrade the image compared > to what it was designed for. You are right, but this Sigma has been designed as more universal lens (something like F/FA 100/2.8 Macro) - it has even "macro" in its name. If you read the article below, you will know, that it performs very good in whole focusing range. Perhaps it uses FREE element as FA 100/2.8 Macro does? http://www.naturephotographers.net/rp0600-1.html
-- Best Regards Sylwek
