Canon 300 TL - Manual (Page 45)

Manual Mode (M Hi/M Lo)
In some cases, automatic flash may not be suitable for
your subject. If, for instance, the subject's surroundings
are bright white with strong reflections or if the main sub­
ject is small with a dark or distant background, the
automatic flash exposure may be affected by the con­
trasting background. Incorrect exposure can be avoided
by using the Manual Hi mode.
In the manual modes, the aperture must be calculated
from the guide number. The aperture is then set using
the electronic input dial of the T90 in the Aperture-Priori­
ty AE Mode. The shutter speed is automatically set to
1/250 sec.
Aperture =
Guide Number
Shooting Distance
• To find the correct aperture, the same unit must
be used for the guide number and the subject
distance. For example, meters and meters or
feet and feet.
Since the guide number changes depending on film
speed and the position of the flash head, the 300TL has
two stickers giving the guide numbers in both feet and
meters for various film speeds and flash head positions.
The sticker should be attached to a convenient place on
the flash unit.
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