Hi all, I just got a new Canon EF 50 mm f 1.8 STM lens. I did a lengthy tripod test on it, keeping the ISO at 200 for every shot, using a 2 second shutter delay so my hands were not on the camera when the lens was open, and took the same shot every time. I also used 2 different cameras, my newish Canon 77D and an older Canon Rebel SL 1, both compact sensor. Both gave me the same results using this lens. At 1.8, the lens was NOT sharp at the focus point. At 2.8, it was quite sharp. At 5.6, 8.0, and even up through 16.0, it was still quite sharp. At 22.0 it degraded again and was not sharp.
I don't really care that it is not sharp at f22. I bought this to use in low light and for general portraits (hoping for some nice bokeh), so I am very concerned that it is not sharp at f 1.8.
My question is, is this normal for this or a similar lens, or is this particular lens defective? If I need to send it back and exchange for another one, I will do that. Thank you in advance for any thoughts on this issue.