This is a brief post to help folks decide which of the following prime lenses is right for them. There are plenty of other prime lenses to choose from but these three are all excellent values. Why should I own a prime?
The 50 f/1.4 offers a wider maximum aperture, letting in more light, slightly sharper at f/2.8 than the 40mm at f/2.8 and offers full time manual focus. Really lovely focal length for portraits, especially on a crop sensor camera like a T4i/T5i. Very wide maximum aperture.The 40mm f/2.8 STM - tiny, makes the DSLR much more portable, quiet but not silent auto focus during video with smoother movement(most useful if you record audio with an external mic), Cheaper and not really noticeably less sharp at f/2.8. Above f/2.8 sharpness is on par with 50 f/1.4. Slightly wider focal length makes the lens a little more versatile. Wide maximum aperture.Best Prices on Amazon Buy the Canon 50 f/1.4 | Buy the 40 f/2.8 STMBuy the 50 f/1.8 (cheapest option) if budget is concern or you think you will only occasionally use this lens.One additional point - prime lenses almost always have excellent resale value- being sold for just a few dollars less than the purchase price years later- if you have taken good care of the lens. Quick illustration of the differences in bokeh between f/2.8 and f/1.4 using the 40mm f/2.8 and the 50mm f/1.4