KB-25 and R-25 are orthopanachromatically sensitized thin-layer black-white negative films of very fine grain, which proporties together with the coinciding grade provide the highest possible edge sharpness. KB-25 and R-25 resolving power is 115 lines per milimetre. These films find their applications particularly in technical and professional photography. Sensitivity of Efke 25 is 14 DIN (20 ASA, ISO 20/14° GOST 18), but by developing in coinciding developers effecting Efkes sensitivity utilization may be even twice increased to 100 ISO.
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