Hello I'm currently using (and loving) the Leica R 180/2.8 APO on my Canon 5D I using Optix v5 adapter with very good results. I previously also used a R 280/4 APO however sold it as it was a used item and the condition was not so good. Now still thinking about the 280/4 APO but it is too expensive now and heavy. Though most of the R-lenses are still usable on canon, Nikon, etc with adapters, but there is still risk of investing too much money on R-lenses. So am thinking about using a R-APO 1.4X adapter with the 180 lens. However, there are two 'versions' of 180/2.8 APO - one can use APO 1.4x but one can't. Unfortunately mine is the can't version. So the other idea is to use Canon 1.4x + Optix v5 adapter + Leica 180/2.8 APO. Anyone have any idea/experience? Thanks!