Samyang is the manufacturer.
I have a Samyang 14 with problems, so I donīt think Samyang sell the better lenses with own brand, and sell worse lenses to Rokinon, Bower, Walimex, Falcon..
It is one of the mechanical worst lenses of my +300 lenses.
I've had a Samyang, Rokinon and a Pro Optic version of the 14mm in front of me at the same time and they were all absolutely identical except from the printed logo. I didn't compare them optically but I seriously doubt they're any different from one another (aside for typical manufacturing tolerances copy variation). I personally owned a Rokinon 14mm for a while and it performed wonderfully.
I have Samyang 14mm and two 85mm (first version & umc). Have no complaint with the 14, but the 85 hood is annoying...can not attached firmly and the focus throwing is too heavy for me.
I agree with you on the 85mm hood. I replaced my Rokinon's with a Hama rubber screw mount.
I've found the Rokinon a real pleasure to use, especially on Sony SLT's EVF with focus peaking and spot magnification. I think the 85 1.4 has got to be one of the best "bang for the buck" alternative lenses out there.
As someone who takes them apart - there's no difference on the inside, either, and the parts are completely interchangeble. We tend to refer to them as RokiBowYang since they're identical other than brand name.
My understanding is Samyang is the manufacturer, the others simply rebrands. They buy from Samyang in quantity, Samyang agrees not to sell their own-branded lenses at less than a certain price.
The Samyang formula is pretty straightforward: they usually model the optics after an older lens (the RokiBowYang 85mm is almost optically identical to the Nikon 85mm f/1.4 D, for example), but put the optics in a much less expensive housing at a very reasonable price.
I own several personally and think they're a great bargain, as long as you realize it's not going to hold up forever (lots of glue inside where others would use screws, thinner plastic housings, etc.) and there is no repair network.
