Very nice start of your review! The thing I am most curious about is how this lens performs with Eye-AF on real humans in both bright and low light.

The 50mm f/1.4 is typical in having a beautifully engineered metal barrel and a full set of weather-seals. The optical design is based on Zeiss’s legendary Distagon principles. The long rotational travel of the focus ring helps focusing precision, and its super-smooth fluidity makes focusing a joy. On the inside, we have 9 elements in 8 groups, three of which are aspherical. The lens is internal focusing, so it does not rotate or extend in use. This is helpful when using polarisers and graduated filters. Minimum focusing distance is 0.45m (1.47 feet), a maximum magnification of 0.15x. This is fairly typical of any traditional 50mm lens.

Your Comments

The corners are even worse and the lens might suffer from field curvature which also affects its corner performance close up.

FWIW, some do not share my opinion but I have never been a fan of the 45/1.8 rendering - tons of sharpness and contrast but that's about all it has going for it - I compared it in some detail to the Sigma 45/2.8 (which IMO produces a far superior look) here: https://www.fredmiranda.com/forum/topic/1616217/1#15153308 Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software. Built for enhanced usability, a custom switch can be set to allow for adjustment of the aperture by rotating the focus ring. Samyang has taken on board hands-on experience from photographers and videographers to increase the usability of this lens. The custom switch can be set to your preferences. Use the optical lens station to set a mode to suit you. Overall build quality of the Samyang AF 50/F1.4 is excelent, easily the biggest upgrade over any other lens they made till date. Samyang in a way always was behind Tamron/Sigma and Sony in terms of build quality but not anymore. This lens is up there with all the other top tier lenses.When comparing to Samyang 45/F1.8 CA and LoCA is a bit better controlled but the improvement is pretty small. Quite a long way from GM 50/1.2, than again you can't have everything for not even 1/3rd of its price. The Samyang 50mm f/1.4 II surprised us with almost no breathing at all. The Zeiss on the other hand has a huge amount of breathing (see our video for the test). Chromatic aberrations The lens includes 9 rounded blades (we will see later on how this effects the bokeh of the lens). Filter This isn't just hype though, as the Z 50mm is terrifically sharp, only fractionally down on the significantly pricier Z 35mm f/1.8 S, and that’s the sharpest lens we’ve ever tested.