reverse mounted, magnification is a little less than life size 1:1.17
Peripheral area is soft, at F2 it is even worse. (35mm full size now)

Setting: used only 40.5->46 + 46->52 + 52->55 (step up rings)
+ 55<->52 (male<->male adapter) + 42->52 (step up) + M42->E
So I cannot change its magnification, and if 40.5->55 (step up)
ring is used the magnification goes down a little but wider view.

With M42 helicoid together, the magnification goes up but DoF
becomes extremely shallow and mechanical vignetting will happen.