From Manufacturer
The Laowa Aurogon FF 10-50x Supermicro Lens for Nikon F mounts from Venus Optics offers a solution for those interested in microphotography but also seeking the convenience of using conventional DSLR cameras. The lens system works in two parts: a primary lens and a set of four magnifying elements in 10, 20, 35, and 50x which can be swapped out for your desired strength. The lens has a set 20mm focusing distance, which is consistent across all of the magnifying units, making it easy to use and switch between them without having to completely reconfigure your set up. The numerical aperture (NA) ranges from 0.15 to 0.5 and is set manually on the primary lens.