Asahi Pentax ES Operating Manual Excerpts
OPEN-APERTURE
OR STOP-DOWN READING
With the new Super-Multi-Coated (SMC) Takumar lenses with an open-aperture reading pin (1), mounted directly on the ES camera body, the TTL meter reads exposure through the fully open aperture or stopped-down taking aperture for correct automatic exposure. For open-aperture reading, the stop-down lever should be DOWN; for stop-down reading, push up the lever.
With all other lenses or when using Extension Tubes, Bellows Unit or Microscope Adapter, remember always to push up the stop-down lever for stopped-down aperture reading and correct exposure.
The SMC Takumar 85mm f/1.9 (photo at the top right) and SMC Takumar-Zoom 85mm~210mm lenses do not have the open aperture reading pin (1), and therefore, they should be used on the ES for stop-down reading.
Also remember that the TTL metering does not work unless the shutter dial is set at "AUTOMATIC".
Reproduced for Historical and Reference Purposes by Paul M. Provencher http://whitemetal.com Not For Resale.