On Mon, 30 Dec 2002, Cotty wrote: > Aside from P-TTL, the other feature that I'm trying to get my head > around is high speed flash sync, So: the button is pressed, the mirror > pops up, the pre-flash fires, the exposure is read and calculated, any > adjustments are made to the flash, (then, crucially) the second flash > fires and continues to fire while the
For P-TTL, the first pre-flash occurs *before* the mirror swings up. It uses the viewfinder's 6 segment metering to calculate the exposure (not possible once the mirror swings up); and the usual off-the-film TTL flash sensor in the mirror box is not used. Once the exposure is set, the mirror pops up, shutter opens and the main flash is fired at the preset level. High speed sync works closely with P-TTL with the same pre-flash; then after the mirror pops up, the flash fires in a series of multiple bursts as the shutter blades sweep across the film. -- --Lawrence Kwan--SMS Info Service/Ringtone Convertor--PGP:finger/www-- [EMAIL PROTECTED] http://www.vex.net/~lawrence/ -Key ID:0x6D23F3C4--
