TTL-flash & digital cameras question.

[melvinch]

Now before anyone whack me left and right, I would like to share a bit of my background.

I have played with cameras like Canon T90, Nikon FE-2 and F801-s since my army days and have been using TTL-flash a lot, especially for macro photography. I have this question in my mind for a very, very long time and hope someone here can give me a satisfactory answer which I can't get anywhere else.

How on earth does a TTL-flash works with digital camera using CCD/CMOS sensors ? With a conventional film camera, flash will be automatically cut off when the camera sensor senses amount of light hitting the film.

But how does a TTL-flash work when the sensor and the film plane are one and the same thing ???

Is that the reason why prosumer cameras like Panasonic FZ30 and Fuji 9500 do not support TTL-flash ? Because TTL flash is not necessary at all ?

 

[espn]

In a very simplified nutshell...

For the DSLRs, there's a preflash does does the exposure calculation and within a split second flashes the output calculated by the preflash.