On Apr 5, 2006, at 8:34 AM, Thibouille wrote:
P-TTL works with A series lenses without distance information too: it
simply defaults the distance information with a pre-determined
constant based on focal length.
But focal length is unknown on an A lens, isn't it?
I love this kind of discussions ;)
Yes, you're right: focal length is unknown. With A lenses, P-TTL
reads the light values only. P-TTL basically requires the aperture
information, uses whatever other information is available in addition
with F/FA/DA/D-FA lenses.
Godfrey
