This lens is much rarer than MACRO-SWITAR 50mms. When I got Alpa 7 camera
it came with it, IQ is much the same as Macro-Switar 50/1.9 but has more 3D-pop.

The total number of this lens made is 1,526 from 1951 to 1955. A double Gauss type,
4 grp / 6 elm, not same as Macro Switar 50/1.8 (5g/7e), there is IR-mark on the lens.
(I disassembled this lens to clean some cloudiness, so 4 grp / 6 elm design is correct.)
MFD = 0.54m, near APO lens you see that IR-mark is very close to distance marker ▲

Non macro Auto Switar 50/1.8s with shutter bulge were made 5,785 from 1956 to 1968.
BTW silver Macro Switar 50/1.8s were made 9,173 from 1958 to 1969, 1,146 black ones.

The lens coating has almost gone, and has some internal reflection. So it does not perform
well against bright background nor white stuff, but it sometime produces very nice photos.
So there is always veiling glare in the images produced by this lens, oh well I like this lens.