Great news from Matthew Gore over at Light and Matter:
However, this is not just the same old lens in new clothing. The optics have been updated and now carry Canon’s latest coatings for improved light transmission and reduced chromatic aberration. The new lens can focus down to 14 inches (.21x magnification), and while the old lens had only 5 aperture blades which created “unique” pentagonal bokeh, the new STM lens has 7 rounded aperture blades for smoother, more natural blur.
This is great. The new lens also appears to be slightly smaller in size, although a bit heavier due to its metal mount — the current “nifty-fifty” is an all-plastic design.
The Canon 50mm f/1.8 II is the best-selling lens in the world by a huge margin, so any improvements they can make — particularly without raising the price — will be extremely welcome.