There are 2 main options : the 120mm Macro lenses from Schneider and Rodenstock, both optimized for digital, to various degrees (can't elaborate on that as a I have no direct experience with them), both 5.6, main difference being the image circle - 110mm for Schneider, 150mm for Rodenstock. I would also love to hear from users who have direct experience with both lenses, on high-density pixel digital backs (6u and 5.2u micron size ... ) , with extreme movements all the way to the borders of the IC !