Amazon.com : 2 Pack JJC 37mm Center Pinch Front Lens Cap Cover with Deluxe Lens Cap Keeper for Olympus Panasonic Canon Nikon and Other Brand of Lenses with 37mm Filter Thread : Electronics
Metalux 2 ft. x 4 ft. 64-Watt Equivalent Integrated LED White Center Lens Troffer, 4000K Bright White 24LCRL4040C - The Home Depot
Lens
Prism Made Easy
File:Convex lens - Object between focal point and optical centre.png - Wikimedia Commons
The center of the lens is called :
Center-Pinch Lens Cap – Breakthrough Filters
Concave lens – Principal focal length and centre of curvatur
A complete guide to help you choose lenses for your Raspberry Pi High Quality Camera - Latest Open Tech From Seeed
Concepts in Light and Optics – Lenses – Part 2 – Esco Optics, Inc.
Definition: Centre of Curvature of a spherical lens - YouTube
Would your vision become worse if you wear large-sized glasses often?