what is is about macro lenses

[Bob Salomon]

E. von... That's for variable spherical aberration, not variable macro magnification.

Then try the 210 and 300mm Makro Sironar lenses. With the front and rear in their normal positions the lenses were optimized for 1:3 to 1:1. Manually unscrew and switch their positions in the shutter and they were corrected for 1:1 to 3:1. A pictograph on the front and rear cell rims showed which went where for the different ranges.

Not a floating element by most people's definition but performed the same task.

At infinity both were mediocre, but from 1:3 to 3:1 with 3 dimensional subjects they were superior optics!

The 120 and 180mm Apo Macro Sironar lenses and the 120mm Apo Macro Sironar Digital lenses are corrected for 1:5 to 2:1 without having to swap the cells around. These lenses replaced the earlier Makro Sironar lenses.

[Old-N-Feeble]

Bob... That's neat but it's more akin to "reversing" the lens than it having a floating element.