I've just got my 50mm 1.4 today and I have been pleasantly surprised at a few things - in good and bad ways.
Compared to the 1.8 it's surprisingly heavy, and a bit bigger in all the dimensions. The focus ring isn't as smooth as I'd like (nowhere near as smooth as my Sigma 10-20 which is like butter) and although better than the 1.8, the build quality still isn't exactly stellar. Again I feel my 10-20 is more solidly built. There is also not
that much difference between 1.4 and 1.8 as far as exposure is concerned. The 1.4 will give you slightly better ability to freeze movement than the 1.8, but not much. You have ever so slightly less DOF at 1.4 obviously but again it's not overpoweringly different, and barely noticeable. The ultrasonic motor is certainly not silent, but it is quieter than the 1.8. It makes a similar shhhh sound to my 10-20. Focus performance didn't seem that much better than my 1.8 at all - it still hunted a little in our living room; my 10-20 AND EF-S kit lens outperform both lenses in this area. It raises the question; what good is a lens that excels in low light that can't focus in low light? Thank god for full time manual focussing, which
IS included with this model, and is one of the deciding factors for my purchase. I can't stand not having FTM.
Now onto the more positive side of things - IQ. I didn't look at this in detail but from the brief comparisons I've done I can say this: Quality even when wide open is very impressive - it surprised me in fact. At f1.8 (and even f/1.4) the picture is relatively clean, miles better than the 1.8 wide open. There was some softness on the 1.4 when it was wide open, but the pictures were still largely free of defects; on the 1.8, there are abberations everywhere on each side of the focus plane, which don't clear up until roughly f/2.5. At f/2.8 both lenses produce superb images; but it is nice to know that I now have a lens which is very good wide open - I would often hesitate using my 1.8 wide open, and would try to keep it above f/2.2, effectively making it a slower lens than it actually was.
One thing I find very satisfying about the 1.4 is looking through the lens with both caps off. Both the hole at the back and on the business end of the lens are
huge and this just shows how much light the thing can let in.
All in all I'm happy with it, upgrading mainly for the better build quality, FTM and the extra light gathering ability. It delivers in these departments.
Do I think it's worth 200 quid more than the 'nasty fifty'? Quite frankly... no - but I bought it anyway
