The composite elements were a spherical glass component with an optical plastic having an "identical" diffraction index, molded to the glass component to form the aspheric element. The optical plastic was the glue...
AlunFoto wrote: > I think the achilles heel of the FA 28-70/4 was actually the quality > of the cement used to glue the elements together, rather than the > elements themselves. Pentax has done a lot of lenses with AL since > then, without repeating the mistake. > > Jostein > > 2008/6/4 P. J. Alling <[EMAIL PROTECTED]>: > >> Interesting, the lens contains not one but two composite, aspherical >> elements, the composite aspherical element was the achillies heel of the >> smcp FA 28-70mm f4.0 an otherwise exemplary little lens. >> >> Dario Bonazza wrote: >> >>> http://www.dpreview.com/news/0806/08060301pentax17-70sdm.asp >>> >>> >>> >> -- >> Vote for Cthulhu. Why settle for a lesser evil... >> -- Dr. Jerry Pournelle >> >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above and >> follow the directions. >> >> > > > > -- Vote for Cthulhu. Why settle for a lesser evil... -- Dr. Jerry Pournelle -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
