I did not see a thread focusing on this lens so I thought to start one. If I missed something perhaps the mods can merge this post into the existing thread.
I tested the lens this afternoon. Well, testing is a big word for what I did but I did some boring comparison shots from f4-f16 for focal length 24-38-35-50-70mm. Photos were made of a brick wall (yawn) and a resolution card. There is noticeable lack of sharpness at f4 at every focal length near the edges. Things improve at every aperture (number) increase. Even f16 looks better than f4. The worst focal length is 35mm as the center is also quite unsharp. In addition, the lens is no match with the 35mm and 50mm primes in my case.
Do you have similar experience? If not, I might have an inferior copy. I am curious to your thoughts and experience.
Thank you.