Mating element aside....How do the FPL-53, FPL-51 and OK-4 Glass types compare?
How do these compare?..... Roland?
Started by zoisite, 06/08/2006 11:29AM
Posted 06/08/2006 11:29AM
Opening Post
Posted 06/08/2006 02:37PM
#2
FPL53 is the most advanced ED glass with the highest V number, which allows a lens of fastest focal ratio to be made. It is the most expensive of the lot. FPL52 is an intermediate ED glass and FPL51 is a first generation ED glass, which is least expensive. OK4 is the Russian equivalent to FPL52.
The overall color correction is dependent on the mating element, and all of these glasses can be made into lenses with any kind of color correction from poor to essentially perfect. The only difference would be that the glasses with the highest V number would have the lowest sphero-chromatism for any given design and F-ratio. Therefore, for equal performance, the ED with the lower V number would need to have a longer focal ratio for equal performance.
Roland Christen
The overall color correction is dependent on the mating element, and all of these glasses can be made into lenses with any kind of color correction from poor to essentially perfect. The only difference would be that the glasses with the highest V number would have the lowest sphero-chromatism for any given design and F-ratio. Therefore, for equal performance, the ED with the lower V number would need to have a longer focal ratio for equal performance.
Roland Christen
