> Acorn, I think the biggest differentiator between these two macro > lenses is the working distance they offer - the longer focal length > allows for your camera to be set further back from the subject to > achieve the same reproduction ratio, and this can be useful if you > need to introduce lighting or if you are working with icky things > (insects or whatever).
As I recall, in the old days the 50mm Micro-Nikkors were designed to have a flatter field of focus - that is, if the subject were flat (like a postage st&) the lens was corrected to be sharp from edge to edge of the image field. Since normally a lens' focus zone describes a hemisphere, if the optics were left alone the corners of the st& might otherwise become fuzzy (since at macro distances depth-of-field becomes paper thin). However, I do not know if the current 60MM macro lens is built the same way - and frankly if that's an issue to you...depending on what you plan to shoot, it might make no difference whatsoever.