"There was a time where fast lenses were scarce in Micro-Four-Thirds land but things have changed quite a bit during the last 2 years. Among the first high-speed lenses was the Panasonic Leica Summilux 25mm f/1.4 ASPH which filled the "standard lens" gap in the system. Its maximum aperture of f/1.4 is certainly fast with respect to light gathering, but in terms of depth-of-field you are effectively "loosing" about two f-stops in this respect compared to the classic full format but this is still sufficient for quite shallow depth-of-field images especially for documentary photography. You should be able to find one for around 500EUR so it is far from being a budget item considering the typical prices for standard prime lenses in the DSLR market."