On Dec 20, 2005, at 1:51 PM, Bob Shell wrote:
On Dec 20, 2005, at 4:25 PM, Godfrey DiGiorgi wrote:
TTL flash metering is supported by the D (built-in flash when
using lenses that do not support P-TTL metering) and by the DS/DS2
when using a compatible dedicated external flash unit. Due to the
nature of TTL flash metering, it must be reading "off the film/
sensor" since it is determining light levels dynamically at the
time of exposure.
None of the DSLR cameras use off the sensor metering. This is due
to problems with the reflectance characteristics of the sensors.
They do TTL metering by measuring a preflash.
That's not correct, Bob. Pentax SLR cameras do P-TTL as the standard
mode, using an integrated ambient/pre-flash metering evaluation, but
they also do traditional TTL flash metering with no pre-flash (the
*ist D with the built-in flash, the *ist DS/DS2 with a compatible
external flash).
Godfrey
