OscarF wrote:
Use an achromatic closeup lens when you want to get closer...
I tried my Nikon 4T achromat (2.9 diopters) with 50/2 AL.
Magnifications are in the 1:6.9-1:3.2 (0.145-0.313) range. However, the achromatic close-up lens induces i) quite evident field curvature (if I focus in the center, the borders are visibly out of focus, and vice-versa) and ii) spherical aberration with consequent focus shift (it's better to focus at the set aperture). Corners are never sharp enough; so other aberrations are induced by the close-up attachment filter.
Probably the more expensive Leica Elpro 52 could reduce such aberrations. However, the Elpro 52 is a 7.7 diopters close-up lens, and magnifications are most likely restricted to the same values attainable with the Leica Apo 50/2 ASPH, i.e. 1:2-1:2.6. A rather limited range.
