Back in October we reported on a bold claim made by a representative of Nikon Japan about Nikon's Z-mount teleconverters. During a conversation between the Nikon rep and the Japanese Kakaku.com Magazine, the (translated) claim was made by Nikon that "by taking advantage of the high descriptive power of the master lens. Image quality will not be degraded." [when using a Z-mount teleconverter].
Check out our original report for a detailed explanation of why we were sceptical of such a claim, but to sum up our thoughts: wherever extra lens elements are used to magnify the image of a host lens, any optical flaws in that host lens will also be magnified, therefore degrading the image quality of the recorded image. Since no lens is optically perfect, the assertion that a teleconverter will not degrade image quality is fundamentally inaccurate.
