An optically-matched M48-fitting doublet field flattener for Sky-Watcher's Esprit 120 ED PRO triplet refractor.
The M48 fitting provides a large clear aperture to reduce halation and a precision thread ensures the triplet and doublet lens groups are precisely aligned on the optical axis perpendicular to the image.
When used with the field flattener the Esprit-120 ED PRO's imaging circle is 44mm.
