I picked up an OM 50/1.8 lens midway through 2015, totally on a whim, and it turned out to be my most-used lens of the year. It inspired me to go all-in on OM lenses, so I picked up a 100/2.8 and a 24/2.8. ...And, for no real good reason, a 50/1.4. The 50/1.8 lens is a "made in japan" variant, considered to be the best of the line. The 50/1.4 is a "Zuiko" 1.1+ million serial number lens, also considered to be the best of the line. I've been using the two lenses somewhat interchangeably, since I almost never shoot wide open, but was curious which one really was the better performer. I set up a test scene with my EM5ii on a tripod, and set the camera to shoot in 40-megapixel high-res mode -- why not? The images in this thread are screenshots of the comparison view in Lightroom. (The 50/1.4 (right) is ever-so-slightly wider than the 50/1.8 (left).) Both lenses were focused on the motorcycle illustration on the Dan Walsh book, both refocused with each aperture change to account for any focus shifting. I was careful to match the front edges of each of the books against the same shelf edge to keep flat with the focus plane. ---- You can click through each photo to Flickr for the full-res screenshots. email@example.com vs. firstname.lastname@example.org Wide open test. The 50/1.8 lens is stronger, a bit sharper and with much less glow on contrasty edges. email@example.com vs. firstname.lastname@example.org (The 50/1.8 does not have an f/2.0 setting, both lenses adjust in full stops.) Two notes. First, the email@example.com gets a bit sharper than the 50/1.8. The glow from the 50/1.4 is gone, and you can make out some detail in the green "Silmarillion" title that's just solid color in the 50/1.8 lens. Second, the 50/1.4 appears to gather more light at f/2.0 vs. the firstname.lastname@example.org -- the scene is a bit brighter in the 50/1.4 shot, AND the camera picked a faster shutter speed (1/100 vs 1/80) for the 50/1.4 lens. email@example.com vs. firstname.lastname@example.org Both lenses performing quite well, but with a definite advantage to the 50/1.4; contrast and sharpness a step above. email@example.com vs. firstname.lastname@example.org Both lenses are very strong at f/4.0, but the 50/1.4 is still ahead here in sharpness, especially at the center. Corners are much closer, maybe even a slight edge to the 50/1.8. ---- Both lenses are great, and honestly I expected the 50/1.4 to lose this match -- just because wide open it's obviously the more compromised, which is the only easy comparison without setting up a test scene like this. Is it worth the extra dosh? Probably not. I'm unlikely to shoot the 50/1.4 wide open because of the glow, unless shooting a low-light portrait. Though I am more like to use the email@example.com vs. the firstname.lastname@example.org, and sacrifice nothing in terms of shutter speed. At f/2.8, both lenses are completely satisfactory. Probably the biggest preference I have is that the aperture ring on the 50/1.4 is a lot nicer than the 50/1.8 lens -- the latter has pretty cheap/plasticky feel, that makes sense when you consider it was a kit lens. The 50/1.8 lens is significantly smaller and lighter, but really both are quite compact. I will probably leave the 50/1.8 on a basic adapter, and use the 50/1.4 with my Metabones Speed Booster (not used in this comparison).