neuroanatomist said:Unless you absolutely need f/1.4, I'd get the 40/2.8.
silvestography said:I'd say try and find a copy of sigma's version 1 30mm f/1.4. You'll be getting a 50mm equivalent, which is a great focal length on which to learn plus a faster aperture than either of the two options you mentioned (for not that much more money). Otherwise, get the pancake for size and better AF.
cbecklund said:Since you mentioned video, I'd recommend the 40mm. It has a lot smoother focus compared to the 50 1.8.