Major's last gasp, their 1958 book:

But even with the cutesy illustrations...

..and the introduction of PRESTO-PATCH

(which even an infant can operate)

...this catalog cannot hold a footcandle to the 1931 book, posted last month, click here to see that one.

However, reader Chris van Goethem makes a very good observation.  In the 1958 book, ellipsoidal reflector spotlights are offered with either dual plano-convex lenses or a single step lens.

At that time, the two leading manufacturers were Kliegl Brothers and Century.  Century's instrument, trade named "Leko" (after inventors LEvy and KOok) featured dual condensing lenses; the Kleigl units featured step lenses.  A page from the 1957 Kliegl catalog shows the difference:
The difference was that Lekos could focus sharp, and Kliegls could not.  For the designer, it was an artistic choice, and in
sophisticated plots of the era, the two were often used in conjunction.


The Major 1958 catalog:

February, 2017.