On May 12, 2005, at 10:43 AM, Cory Papenfuss wrote:
...A series lenses are fully enabled for P-TTL operation when the lens' aperture ring is set to "A". When you set the aperture to anything else, they operate as a K/M bayonet lens and flash is fully manual.
So the manual is incorrect (p 177)? That table says on an 'A' lens, P-TTL is No, and TTL is Yes with the footnote that it discharges fully. That's self-inconsistent, no?
Yes, the manual is incorrect. A lenses work exactly the same as F/FA lenses.
The DS does not have TTL flash metering as an option without an external flash unit, only P-TTL and full unmetered output. With a dedicated external flash unit like the Sigma EF 500 DG Super, it supports both P-TTL and TTL; you force it to TTL mode with A series and all autofocus lenses by setting the aperture ring off the A setting. With K/M bayonet lenses, you need to be on manual exposure anyway for the lens to stop down.
Hrm... that's odd, but I guess in consistent with the manual and my observations. If I understand you correctly, you'd have to have an external flash that supports P-TTL and TTL in order to use the *internal* flash in TTL? I see on p153 that TTL doesn't work on the internal flash. Odd.
The DS' built-in flash will ONLY operate in P-TTL or full power manual mode.
You use a dedicated external flash unit that supports P-TTL, TTL, and other modes, to get traditional TTL flash metering. The built-in flash is not used when you're using an external flash unit.
Godfrey
