Two weeks ago, while traveling for multiple shoots in Charlotte, my favorite lens, Canon’s EF 50mm f/1.4 USM died, in the camera bag, due to Canon’s well-documented design flaw.
The Canon EF 50mm f/1.4 is not a ring type USM, it is a Micro USM. A word of advice: buy a hood and also park the lens at infinity. If you don’t the front of the lens will protrude from the barrel. Any force on the front of the lens can bend the plastic focusing helical, causing the USM to fail.
The first symptom is a failure of the AF mode, eventually the lens will fail to focus manually, as well. Thankfully, I had a Nikkor F-mount 50mm f/1.2 that I keep in my bag, along with a Nikon to Canon EOS adapter. Yes, you read that right — in order use my preferred, Canon-manufactured cameras, I had to utilize Nikon glass.
The Sigma 50mm f/1.4 is more expensive and heavier, but suffers from backfocus issues, especially wider than f/4. The Canon 50mm f/1.8 is cheaper, but exhibits vignetting until f/4, has harsher bokeh and has AF issues in low-light. The EF 50mm f/1.2L lens has suffered from backfocus issues since introduction, with users reporting multiple trips to Canon’s service centers before focus was acceptably accurate.
I’m sending my copy off to Canon, along with a letter explaining my belief that a high-end prime lens shouldn’t fail while sitting idly in a camera bag. Perhaps they’ll listen. Perhaps not.