Pentax and Schneider-Kreuznach
12 and 5 researched events on one shared scale. Pentax 1919–present, Schneider-Kreuznach 1913–present.
The axis stretches where either maker has research and collapses where neither does, so a year sits opposite the same year on both. Event counts differ because research depth differs, not because one company did less.
Pentax1919–present · 12 events · 2 concurrent threads
Schneider-Kreuznach1913–present · 5 events
Read either maker on its own: Pentax · Schneider-Kreuznach