IR corrected Zeiss Jena "special secret" lenses

kds315* · Expire: 2021-03-09

Well, many years ago in times of the cold war, Zeiss Jena had to
develop special lenses for a very special ministry (dig you guess
which one I mean), which are hardly known to the public, but
available. These are corrected for focusing in visible light, but
also for shooting in (deep) invisible NIR. There were also special
noiseless cameras developed for these lenses.

To make things clear, I distance myself from that former purpose,
but am interested in the performance of those special lenses!

The lenses were designed in such a way that the aperture location
was in front of the lenses, which allowed shooting through
small holes in walls, through button holes in bags etc. - I guess
the purpose gets clearer now. A set of fixed apertures and also
a variable iris usually comes which each lens. All these lenses
cover the full 24x36mm format.

I was able to get a set of these very special lenses thanks to
the contact to and the efforts of Detlev Vreisleben, a german
engineer who, after his retirement has concentrated to shed
some light into these.

(c) Detlev Vreisleben

Here a list of these lenses (SO = "Spezial Objektiv")

SO-3.1 f2,8/35mm a FLEKTOGON wide angle

SO-3.2 f2,8/50mm a BIOTAR normal angle

SO-3.3 f3,5/75mm a TESSAR short tele

SO-3.4 f3,5/135mm a SONNAR tele lens

They have a special mount M36 diameter, but are easily
adaptable.

First tests have shown very good to excellent sharpness
in VIS as well as NIR. More about that later...