Hello Tom...thanks for replying...I am aware that the f/4 is 1:4 (price is the consideration vs the f/4.5), but I must admit that I don't know how 1:1 or 1:4 translates from subject to image on my film...I do understand ratios, but if I'm photographing a pack of cigarettes on table, what does 1:4 mean?...can you help me with this?...and how does a macro lens treat depth of field (imagine five packs of cigarettes in a pile and needing to focus only on the top pack, and then focused on all the packs)...as an aside, I have tried a close-up filter, but the DOF is not satisfactory...and ps, I've Googled for this information, but I remain confused by overly technical explanations...