Is anybody here who can commit to the quality of Samyang/Rokinon/Wallimex Optics?
I have owned 4 of the 24/1.4 Rokinons and returned all of them.
Everyone raves about their excellent coma performance however I suspect that the "reviews" are biased towards DX format DSLRs and/or web sized images.
The 24/1.4 has the ability to be an excellent minimal coma lens (on FX and large images) as was the case for one of the copies I had. Unfortunately there was way too much focus slop which made critical focusing on stars a nightmare, so back it went. The two other copies had excellent coma performance in 2 of the 4 corners (optics misaligned) and the fourth copy was just plain soft.
I have a friend who has rented this lens twice and both copies suffered the same issues. If you rent one and find it "perfect" then offer to buy it for full price, I would.
I really want to like this lens (for nightscapes) and it's been over a year since I bought my first copy and 6 months since my last copy. The experience and frustration is fading so I might be tempted to try again.