I love this little lens when it works correctly, but mine has a terrible front focusing issue when in lower light situations. By lower light, I mean just about anything indoors. If I have good light or sunlight, the issue goes away completely and I get very correct focus. I've tested it in a number of situations, and it is very reproducible. I never hear the AF hunting, it just comes out front focused, and when using larger apertures, it is very noticeable.
My question being, is this common for this lens? Trying to decide if I should buy another one or save up for the 50 1.4, which I hear gives close to the same image quality but costs 4x as much