You can't go wrong with the C-Biogon. It offers the best small size and high resolution compromise on the market. The APO summicron resolves marginally higher, has a much more pleasing color rendition, lower macro contrast but higher micro contrast and it really the best on the market but it costs 10x more and is bigger and heavier. But for most applications, the resolution of the C-Biogon would be more than enough.