The Minox Model BL is essentially a redesigned Model B with the addition of a semi-coupled CdS (Cadmium Sulfide) exposure meter. The CdS meter is more sensitive and reliable than the earlier selenium cells used in the Minox B. As a result, it requires batteries where all earlier Minox models did not. All other camera functions remain completely mechanical.
Less than 18,000 were produced during the short production run in 1972–1973. The low number available combined with what some see as the “perfection” of the mechanical Minox tend to drive up prices in the used market.