Pentax 500FTZ Operation Manual - Page 16

WHEN USING THE "A" (AUTO) LENS APERTURE Programmed TTL Auto Flash is possible with the AF500FTZ when the Programmed AE or ShutterPriority AE mode is set on the camera (Possible when the Aperture-Priority AE mode is set on the Z-1/PZ-1). The flash sync shutter speed and/or aperture value automatically vary depending on the subject brightness, making it suitable for daylight fill-in flash. WHEN SETTING THE LENS TO A MANUAL F/STOP When the Aperture-Priority AE or Metered Manual mode is set on the camera, TTL Auto Flash is possible with the desired aperture selected to control the depth-of-field. (The flash sync shutter speed will vary depending on the subject brightness when the Aperture-priority AE is -set on the Z-1/PZ-1.) In Metered Manual exposure, slowspeed-sync flash is possible. 14 CALCULATING THE FLASH EFFECTIVE RANGE When setting the lens to a manual f/stop, calculate the guide number at FULL output intensity using the zooming position and film speed. Divide the resulting guide number by the aperture in use. Thus, the maximum distance is obtained. The minimum distance is obtained in dividing this max. distance by approx.15. (See "Table of Guide Numbers" on page 16.) However, if the minimum shooting distance is shorter than the shooting distance listed in the "Table of Minimum Shooting Distance According to the Focal Length" on next page, the distance on this table will be the minimum distance. Example: With ISO 100 film and a 50mm lens at 4 (f-number) 1 If the zoom position = 50mm, and film speed at ISO 100, the guide number is 42. 2 Divide the guide number 42 by the aperture .f/4. The result is 10.5m (max. distance) 3 Divide the max. distance 10.5m by 15, and the result is 0.7m (min. distance). However, the minimum shooting distance for the focal length 50mm is 1.Om. Thus, flash effective range is approx. 1.0 to 10.5m (3.3 ft. to 34.4 ft.)