Olympus DE-N3 camera lens adapter

Diopter-Correcting Eye Cup DE-N3 (for negative correction extension) The DE-B3 provides diopter extension in the negative direction by shifting the diopter by -3m-1. When installed on the viewfinder eyepiece, the diopter can be extended down to -6m-1 so that even shortsighted users can see the viewfinder images clearly.
Like the DE-P3, the DE-N3 is also a large-sized eye cup with an easy-to-attach/detach slide-in type mechanism. To help screen out extraneous light (including sunlight) the cup is made of a soft rubber material that is comfortable and eye-friendly.