Canon 188A - Manual (Page 39)

distance using the guide number of formula
and then set manually on the lens' aperture
ring. The procedure for manual flash photo­
graphy is as follows:
1 Set the 188A's Aperture/MANU selec­
tion switch to the lowest position;
"MANU” will appear in the Aperture/
MANU window
2. Make sure that the proper ISO film
speed is set on the flash
3 Focus the subject
4 Read the shooting distance from the
lens' distance scale.
5 Calculate the aperture using the fol­
lowing guide number formula;
. guide number
Aperture = —r—r—-----------------
shooting distance
6 Set the aperture on the lens
7 Turn the main switch ON
8
Do not press the shutter button until
the pilot lamp glows.
*
The 188A's guide number is 25 (ISO
100-m) or 41 (ISO 25-ft.)