Whats TTL

[Frenchy2005]

I have heard this alot recently and I am new to photography so was wondering what it means?

 

[Mako Mark]

TTL means through the lens metering

It basically means that your camera measures how much light comes through the lens from the strobe etc, and when it is enough, it shuts off the strobe and or closes the shutter!.

I am sure there are far more expert people on the board, but that is the basics.

 

[trob09]

Through The Lens - TTL

 

[RonFrank]

I have heard this alot recently and I am new to photography so was wondering what it means?

As others have said. It's known in SOME systems as OTF (off the film).

In theory the *flash* is measured independently from the ambiant exposure, and once the *correct* amount of flash was measured based on the aperture set ON the flash (not the camera) hitting the FILM plane, then the camera shuts down the strobe. This all happens VERY fast, at the speed of light!

With digital I'm not longer clear how may camera's actually TTL by measuring off the film plane (the sensor). Most have sensors build around the film plane, and implemetations of TTL seem less sucessful with digital, but are getting better. DTTL (nikon) was the first version of Digital SRL TTL, and it was quickly replaced by iTTL which is better. Many use preflash to determine flash output, which is NOT as good in that preflash is NOT what is hitting the sensor during the actual exposure.

TTL is a reflective type of meter, and like any reflective meter it is based on 18% grey, and easily fooled.

Ron

 

[ReyeR]

In simple terms, TTL is a method of measuring the amount of light (ambient or flash) coming from a scene by placing sensors behind the lens. TTL metering can be used to control both the camera and the flash.

For example, when a camera is used in full-auto mode (also called Program mode), it uses TTL metering to determine both the shutter speed and aperture for what it thinks is the correct exposure. Or when used in full-manual mode the camera uses TTL metering to indicate (usually with a + or - exposure value) whether the exposure is going to be correct for the shutter speed and exposure you have chosen.

For TTL flash or strobe photography the camera uses TTL metering to control the strobe itself and quenches the strobe when it thinks the scene has been lit properly - so in a way the camera is 'talking' or 'communicating' with the strobe. For this to work the flash must understand the TTL protocol or language that the camera uses. Unfortunately different manufacturers use different protocols, making it difficult to swap strobes between manufacturers.

 

[Frenchy2005]

Hey Thanks a lot for the help.