>>3595911>viltrox ef-m extension tubesIf you're talking about hollow ones, then yes.They are flimsy, and they soften corners, almost without exceptions. They move whole lens forward, so natural curvature of the lens becomes more prominent, this manifests itself in slight centre and noticeable corner softness.
They reduce nearest possible focusing distance of a lens, but since macro lenses already have close focusing distance, they have little effect on them. You may get slightly higher magnification on macro lens using them, but that's all, it will still soften image. They are mainly used on non macro lenses, they turn many of them into macro lenses with decent to very good results. Depending on the lens you fit them on.
Better alternative for macro lenses are macro and close up filters. Hoya, raynox, even no name ones will increase magnification, with as good or better centre sharpens, but again with some added corner softness.
