Re: F v FA Lenses

[Godfrey DiGiorgi]

The distance information is used in P-TTL flash metering as well as  
in matrix metering when you set the option to link AF and AE systems.  
It is also used to select preset modes when you set the DS into Auto  
Picture mode ... the camera knows what lens you're using and what  
distance your subject is and makes a guess as to overall scene type  
on that basis.

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.

Godfrey