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the non-TTL units they again have to be used in the full manual mode.
Most units support both hot shoe and the PC (pronto-compur) cable
connections to allow connection to a variety of flash guns.
If you use a fixed intensity flash unit where there is no adjustment for
output power you will need to use the flash “guide number” to be able to
set the camera aperture.
The guide numbers are usually in metres, so for example a flash unit
with a guide number of 32 at ISO 100 will give an exposure of the guide
number/ distance to subject (in metres).
If our subject is 5 metres away then the aperture is then set to 32/5
which is f6.1. The ISO would be 100.
Most flash units have some form of table which helps you establish the
correct aperture for any ISO setting and flash to subject distance.
My National dual head flash
gun with side flash bracket
used with a PC cable
connection to a “hot shoe”
adaptor. This unit has
bounce facility with lower
power –“fill in” flash. A
very useful unit for parties
etc.
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