Is that conclusion from technical testing, or is it an opinion?
It was from me taking a bunch of pics to compare the two before I sold the 1.8. I was curious myself what the difference was so I took some test shots of action figures in a DIY product box at various apertures and the results were most similar to those on The Digital Picture. So... I guess I just got lucky with my copy.
Derrel, don't you have a 50 1.4? How does it compare? Do you think the 1.8 II is better?
There has been some speculation that the recent 50/1.4 EF lenses, like those tested in the five-sample test, since they are all wonky on one side, might be suffering from some type of assembly line fault or flaw, or perhaps are suffering from some type of parts problem. Like the owner of Lensrentals.com wrote a while back, lens makers can have "problems", and sometimes the problems come from parts suppliers which make and sell parts to the camera/lens makers; if a part, like a retaining ring or spacer is out of spec a little bit, it can have,potentially, very severe effects on entire batches of lenses built with those parts. THis is not a one-manufacturer issue, and the Lensrentals guys write some pretty good articles about quality control and breakdowns, and so on.
Nikon's D2h had the horrible "dead meter" syndrome, due to a part they bought from a 3rd party supplier...NASA almost had some dead astronauts years ago due to a supplier's QC issue...it's a real bugger to track this kind of stuff down. Anyway...five consistently bad lenses, all out of whack on one side...that sounds like a systematic problem, either on the assembly line, or with the component parts, or with some type of QC issue "somewhere". The earlier 50/1.4's never had this reputation....these lenses were tested in January of 2010...my 50/1.4 EF is from 2007,and seems to be quite a good 50mm lens. I have not tested it really super-critically, but it seems pretty flare-resistant, adequately sharp, and reasonably reliable.
I had a 50 1.8 EF-II, the current plastic-mounted lens, made around 2005, and it was a flare-prone, green-ghosting piece of crap. One of the absolute worst 50mm lenses I have ever owned, and I have owned a lot of 50's, from the 60's,70's,80's,and the 2000's. While it was SHARP and the contrast was good, it has other problems, like horrific ghosting and flare when shot toward strong light in the summertime...it was simply really,really crappy; the flare-resistance of a 50mm is, to me, a critical issue. If you cannot point it toward a light source, either during the day, or in dim light, and have it resist flare or ghosts, or both, to me, it is useless as a fast 50mm lens. So, in that respect, my 50/1.4 EF is a much better lens than the 50/1.8 I gave away.
Sometimes a lens maker will make unannounced changes to either a lens design, or to its manufacturing process; sometimes I think the changes are for the better, but one of the things Japanese camera companies try to do is to figure out ways to increase efficiency or to cut corners to increase profits on products they have made for a while; I think it is possible that the more-recent 50/1.4 lenses might have some type of a fly in the ointment,so to speak. Maybe they got some bad retaining parts, or maybe the way the lenses are held in the assembly jigs is allowing a slight decentering, since the rigorous lab tests are showing the 1.4's are suffering all on ONE side,and the problem is not random, but fairly uniform. That seems like a process error to me...
Sorry for the long post.