Hmm. Live by the catalog, die by the catalog.

I make this point because I recently had the opportunity to confront what two Berthiot catalogs (pre-WWI, between the wars) and one Berthiot brochure (post-WWII) say about Perigraphes' (Serie VIa, f/14; Serie VIb, f/6.8) coverage. It fell over time. In the case of the VIb, from 95 degrees to 65 degrees.

Further on this point my friend and co-author Eric Beltrando (see his site, has used a ray-tracing program he wrote to evaluate a number of lenses' performance, including coverage, using prescriptions from patents and from as much of the Boyer archives as he has. Short answer, in general coverage claims are exaggerated. This is especially the case with Boyer's Beryl, a clone of Goertz' Dagor, and the Dagor itself.

Faith in coverage claims published in catalogs seems, um, misplaced. The best way to know what a lens will do for you is to ask it.