need help,what TTL mean?
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Scubaroo
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TTL = Through The Lens - it refers to the method used to meter light. A Google search would turn up a lot of information, TTL is not specific to underwater cameras.
I believe it's Through The Lens.
norcaldiver
Guest
From http://photonotes.org/articles/eos-flash/#ttl
TTL (through the lens) flash metering.
The earliest electronic flashes required the photographer to perform distance calculations by hand. Later, the first generation of automatic electronic flash units relied upon external sensors to determine the flash exposure setting. These sensors, mounted on the front of the flash unit, simply recorded the flash bulbs light, reflected back from subject, and cut off the power when enough light for a satisfactory exposure was determined.
Of course, such external sensors were easily fooled. The sensor might, for example, cover more or less area than the lens currently in use. So Olympus pioneered through-the-lens flash metering in the mid 1970s with the OM2. Canon later included TTL flash metering in their T90 camera a decade later.
TTL flash metering works by measuring the pulse of flash-generated light bouncing back off the subject and entering the lens. It actually measures this light reflecting off the surface of the film itself, in realtime, by using an off the film (OTF) sensor. The light from the flash bulb is quenched when the sensor determines enough light has been produced to achieve a satisfactory flash exposure to get a mid-toned subject.
TTL (through the lens) flash metering.
The earliest electronic flashes required the photographer to perform distance calculations by hand. Later, the first generation of automatic electronic flash units relied upon external sensors to determine the flash exposure setting. These sensors, mounted on the front of the flash unit, simply recorded the flash bulbs light, reflected back from subject, and cut off the power when enough light for a satisfactory exposure was determined.
Of course, such external sensors were easily fooled. The sensor might, for example, cover more or less area than the lens currently in use. So Olympus pioneered through-the-lens flash metering in the mid 1970s with the OM2. Canon later included TTL flash metering in their T90 camera a decade later.
TTL flash metering works by measuring the pulse of flash-generated light bouncing back off the subject and entering the lens. It actually measures this light reflecting off the surface of the film itself, in realtime, by using an off the film (OTF) sensor. The light from the flash bulb is quenched when the sensor determines enough light has been produced to achieve a satisfactory flash exposure to get a mid-toned subject.
try this link for some additional photo terms:photo terms
for some folks, myself included, TTL stands for transitor-transitor logic. It's an electronics term.
for some folks, myself included, TTL stands for transitor-transitor logic. It's an electronics term.
Gilligan
Contributor
TedJ
Contributor
Very nicely done.
TEdJ
TEdJ
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