Here are prescriptions for two Steinheil Aplanat Periskop lenses:

wide angle (90 degrees): http://www.dioptrique.info/OBJECTIFS1/00022/00022.HTM

narrow angle (45 degrees): http://www.dioptrique.info/OBJECTIFS4/00181/00181.HTM

Also see Eric's comments on Periskops at http://www.dioptrique.info/base/comp...s/periskop.HTM

Both lenses are symmetrical, both are, by modern standards, dreadful. If you want to calculate the performance of lenses for which you have prescriptions, you can download his program 030 from here: http://www.dioptrique.info/base/comp...s/a_propos.HTM