Ya I was going to ask does anyone know what the tradeoffs are when you make a lens higher magnification. Clearly there must be serious tradeoffs or everyone would just mag 2x+ macro lenses. Since they don't, why not?I didn't even know 4:1 equivalent magnification is possible.
I am going to speculate that this lens has an actual optical magnification of 1x and the "2x" is Oly making an equivalent comparison.
Edited to update: This page...
does a great job of explaining how to achieve larger magnifications and the drawbacks to doing so. Chief among the drawbacks is an effectively roughly 2-stops slower at 1:1 and of course continues to slow down as you increase magnification. So for example, if the 100/2.8 macro is shot at 1:1 you are really shooting at f/5.6.