Maybe you have been attracted by the thought of the far lighter bodies of micro 4/3 cameras or the amazing array of functions (superb video and precision focusing aids for example) they boast  but been deterred by the 2x crop factor from changing formats – or even adding a body via an adapter and using manual focus on your lenses. Metabones have produced a intriguing optical device – the Speedbooster XL 0.64 that lowers the crop factor substantially  (to 1.28) and also produces an increase in the speed of the…