SVBONY Ultra Flat Field 10mm Eyepiece 60 FOV The 1.25 UltraFlat Field Eyepiece features a high quality standard and a very compact design, which is designed to remove the field curvature at the edge, resulting in a flat, distortion-free image up to the edge of the visible field of view, even in very fast telesocpes. The eyepiece has over - sized eyepiece lenses for the largest possible field of view and a 20mm eyerelief - also suitable for spectacle wearers, the eye-rubber allow a comfortable view.All lenses have a braod-band-multicoating (FMC) and blackened lens edges. The plug-in sleeve is equipped with a thread for 1.25 filters. SVBONY Ultra Flat Field 18mm Eyepiece 65 FOV The SVBONY 18mm Ultra Flat Field Eyepieces offer a perfectly flat field of view and a distortion-free image even when used with very fast telescopes. Made with oversized lenses, the highest possible field of view is maintained as well as long eye relief. All of the lenses in this eyepiece design have broad-band multicoating (FMC) with blackened lens edges to remove spurious light reflections. The 1.25 eyepiece barrel is threaded to accept standard 1.25 eyepiece filters. 65apparent field of view and long eye relief for comfortable viewing. Remove the field curvature at the edge Fully Multi-Coated All of the lenses in this eyepiece design have broad-band multicoating (FMC) with blackened lens edges to remove spurious light reflections. Standard 1.25 inch thread The 1.25 eyepiece barrel is threaded to accept standard 1.25 eyepiece filters. Eye relief:16mm/20mm Field diaphragm:14.7mm/23.4mm Specification: How to use it?