u/Hot-Statistician-559

I bought an Olympus 12–40 f/2.8 lens.

At f/2.8, images taken with this lens are quite blurry, but at f/4, the image quality improves significantly.
I’m comparing it to the 40–150 f/2.8 lens.

A photo taken with the 40–150 at a focal length of 40 mm and an aperture of f/2.8 is incredibly sharp, whereas with the 12–40 f/2.8, it’s blurry.

I bought the lens secondhand.

I’m attaching a photo taken at a focal length of 40 mm and an aperture of f/2.8, along with a close-up of the defect.

Please help me with this