雙凸鏡片，N-BK7 光學玻璃*

Ordered two of these for a small relay setup and the figuring is excellent, edges stay sharp across the whole field. The glass arrived spotless with no chips and both lenses matched closely in focal length.

The N-BK7 glass gives really clean imaging over the narrow spectral range I'm working in, no noticeable distortion at the edges. Polish quality is excellent right out of the box.

I needed a lens for a specific narrow-band imaging project and these biconvex lenses delivered exactly the performance I hoped for with the N-BK7 glass.