Pentax SF-1n SF-1n Manual - Page 41

• The Program Flash system can be used in combination with a Pentax-F or -A lens. Be aware that the RTF's discharge may be cut off by wide-angle lenses or lenses with a large diameter. • When the following lenses which may cut off the RTF's discharge; * Lenses with a focal length of less than 35 mm * Lenses with a focal length of over 210 mm * Macro lenses the shutter can be released but the RTF will not discharge. • Do not use a lens hood. The RTF's discharge is also cut off within the distance of 1m when a 35mm wide angle is mounted, so do not use the RTF in such cases. • Be aware that photographing a person straight on from the front using a flash beyond a distance of 3m may cause the "red-eye" phenomenon produced when light reflects off the retinas. • Be sure to push the RTF back down into the housing after use. If you leave it in the "up" and "charging" position, the battery will be exhausted in about two days. AF Spotbeam Projector When using the RTF in a dark location, the AF spotbeam projector automatically emits a red beam to assist the auto-focus system. The spotbeam projector can also be used in dim locations where the auto-focus system may not work effectively. • The AF spotbeam projector can be used only when the focus-mode switch is set at the SINGLE position. It will not work at any other position. • The AF spotbeam projector's effective range is approxi- mately 1m to 4m. If flash illumination is unnecessary, push down the RTF unit after the AF system captures the subject in focus. • The AF spotbeam projector does not operate for bright subjects. • If the ] indication appears, auto-focusing is impossible. (See pages 31 to 33) • When the AF400FTZ's or AF240FT's AF spotbeam projector is used, the AF spotbeam projector built into the camera does not operate. Red-eye phenomenon: The Red-eye phenomenon occurs when the flash illumination reflects off the retina because the pupils open up in the dark. Although it is impossible to prevent it entirely, it can be minimized by lighting up the location up to about EV8 level or shooting in a close distance from the subject. 39.