I am planning to establish a table top set-up in my basement with backdrops, staging and appropriate lighting to begin photographing still life compositions, and I am considering purchase of a macro lens(es) for this purpose. There will be a learning curve, but that's part of the plan and the fun. In my research to date I see there are "macro" lenses from the big three or four makers available mostly in 120mm and 180mm focal lengths, but I am wondering which would be the most useful focal length for me to consider as a first purchase? Any other advice you might offer for lens choices would also be appreciated. My camera will be a Linhof Technikarden 45S. Thanks in advance for your help...