Schneider 138mm SPLIT Diopter Set

Schneider-Kreuznach 138mm split diopters are used primarily to achieve a “deep focus” effect by keeping two distinct planes—foreground and background—in sharp focus simultaneously.

Two Planes of Focus: It is a semi-circular piece of glass (essentially half a magnifying lens) mounted in a ring. Half the frame captures the foreground through the diopter, while the other half captures the background through the native lens.
No Exposure Loss: Unlike stopping down the aperture to increase depth of field, a split diopter does not require additional light or exposure compensation.
Macro-Like Results: They allow standard lenses to capture sharp, extreme close-ups of tiny subjects without needing a dedicated macro lens.
Anamorphic Solutions: They are essential for anamorphic lenses, which often have very limited close-focus abilities.
Matte Box Compatibility: Designed for standard matte boxes like the ARRI LMB-5, LMB-15, LMB-25 and LMB 4×5.