The entire flat field Dyna series, Balplan and Microzoom scopes were based on that design principal. A couple of other of their engineers worked on and patented the 2.5X .30 or when multiplied 12.5X flat field apochromat and the 5X .65 or when multiplied 25X flat field apochromat, which seem to be the only one's catalogued. George Aklin also patented at least 2 others, which apparently never went into production, according to Jay Margolis : a 15X 1.2 or when multiplied 75X oil flat field apochromat and 25X/125X 1.4 N.A. oil flat field apochromat. There were several flat field fluorites and at least one 10X .80, therefore 50X planfluorite and a standard fare of .5/2.5X .06, .8/4X .09, 2/10X .25 ( in a l.w.d. version too), 4/20X .50, 8/40X .65 and 20/100X 1.25 flat field and plan achros. There were epi objectives too and epi D.I.C.
The Microzoom had a whole range of low power l.w.d. industrial planachromats up to 10/50X.
For years I was baffled by the inexplicable performance or lack of when Balplan objectives were installed in other microscopes and visa versa.
https://www.microbehunter.com/microscop ... t=breaking