watt100 wrote in post #14511309
lens collections can grow. But I want to put Canon lens on a mirror-less system
Sure they can, but there is no guarantee they will grow fast enough....
How long has the Sony Alpha mount been around? I believe it started out as the Minotla Maxxum/Alpha mount back in 1985, and Sony took over in 2006.
Sure, the Alpha lens collection has grown over the years, but how does it compare to the Canon EOS or Nikon F lens collections?



Nobody knows how many lenses Canon will introduce with its mirrorless system (although rumour has it 3 lenses will be announced at the same time as the body, and there will be a roadmap showing what is to come).
Also, no one knows if the EF/EF-S backward compatibility will be full or "crippled" -- as you may have read by now, conventional DSLR lenses are optimized for phase-detection AF, and they don't work very well with contrast-based AF, which almost all mirrorless cameras use.
People with Olympus DSLRs quickly found out how slow their DSLR lenses work on the mirrorless bodies. Sony tried to get around the same problem by having a separate phase-detection AF unit in their adaptor, but this increases the bulk/cost of the adaptor, plus some light loss (due to the use of a pellicle mirror).
However, my reply you quoted was actually targeted at NEX (which Croasdail has), not this yet-unknown Canon mirrorless system. 
The NEX system was first announced in May 2010, yet in two years, Sony has come out with only 7 lenses. (They have been busy introducing bodies though -- 6 so far.)
In comparison, m4/3 has been around since August 2008, and in less than 4 years, Olympus and Panasonic have come out with a total of 28 lenses (Olympus 13 and Panasonic 15).
However, the number of lenses is only half the story.
Even more important is the variety of lenses available. In m4/3, you can find a wide variety of wide-to-tele zooms (including a constant-F2.8 12-35, a weather-sealed 12-50 which can also do pseudo-macro, a collapsible "Pancake zoom" 14-42, a few superzooms, plus several generations of the kit lens), in addition to quite a few tele zooms including a 100-300 (giving 600mm FOV), several pancake primes, and perhaps most importantly, many fast (F1.8 or faster) primes (including the latest 75mm/1.8).
Do I wish I can use some of my EF/EF-S lenses on the OM-D E-M5? Of course. 
However, there is definitely enough breadth and depth among native m4/3 lenses for it to be a viable alternate system for serious photographers....
