Canon Fl400mm F5.6 Instructions Manual

20• The rotating volume of the lens is 120 degrees to left and right , or atotal of 240 degrees , with the horizontal position as the standard3 . Operation of Apert u re3 - 1 Automatic apertureThis is the mechanism with which the desired f / stop is preset . Thepreset aperture ring is used When the A·M aperture ring is set at Aposition, and the preset aperture ring is set at the prescribed f / stop ,the aperture automatically closes down to the preset f / stop for the in·stant that the picture is being taken and then returns to full apertureopening after the shutter has been released.3 - 2 Manually operated apertureComplete manual operation of the aperture is possible by setting theA·M aperture ring at M position. The f / stop can be freely changed byturning the preset aperture ring .The same effect can be obtained by keep i ng the A-M aperture rin g setat A position and then t ipping the stopped · down metering lever towardsthe lens side and locking it . With this met hod , deciding the exposureand conf i rming the depth of field can bot h be performed at the sametime .