DxOMark felt the pulse of the manual focus Samyang/Bower/Rokinon 24mm f/1.4 (price & specs), and it turned out the Samyang got the same DxOMark score (31) as Canon’s Ef 24mm f/4L II lens (price & specs). The Canon is sharper and has less distortion but the Samyang produces less vignetting and chromatic aberration are better controlled at all apertures.
From the conclusion:
Although the Samyang is a phenomenal performer, when stopped its sharpness wide open doesn’t match that of rival high-speed designs. Given the modest pricing [$669] it will no doubt continue to be a popular model but it would be all the more attractive with the addition of automatic aperture control and perhaps AF-assist (though it’s often unreliable without experience). There’s another, often overlooked benefit from the inclusion of data transmission – EXIF data stored in Raw files could be used by third-party software suppliers to apply lens corrections. Future updates such as these would seem likely but for now the Canon mount version is overshadowed by the better performing rivals.
It is up to anyone to know if a manually operated lens like the Samyang is ok for their needs. The optical performance is very good and if you have at last a minimum of photographic experience, then this lens shouldn’t be a problem at all.
Samyang/Bower/Rokinon 24mm f/1.4 price check: Amazon, B&H, Adorama, Canon USA, J&R, Digitalrev, Borrow Lenses, eBay
Canon’s Ef 24mm f/4L II price check: Amazon, B&H, Adorama, Canon USA, J&R, Digitalrev, Borrow Lenses, eBay
Specs and description after the break.