GOI Mercury–1 2/5.2cm prototype M39

An extremely rare GOI Mercury-1 2/5.2cm prototype lens in rangefinder-coupled Leica M39 mount.

The optical construction is a mixture of the best features of Leitz and Zeiss lenses from its time — it shows a compact, rigid mount and non-rotating front element, it is an advanced optical construction with 7 elements in 5 groups, with round aperture opening and f-stop range from f:2 to f:22.

The optical elements are coated with unique amber colour. The lens comes with two matching aluminum caps and a special bakelite keeper.

Mercury-1 was never released and for a long time was only known from the GOI catalogues. Today, only a few examples are known to exist.

Photo credit: © Leitz Photographica Auction