What is TTL?

[Cero21]

I've been looking a couple flashes and they all state TTL auto and such like that. What exactly is TTL?

 

[Sw1tchFX]

Through-The-Lens

 

[table1349]

Through-The-Lens

Darn, I thought it always stood for Tough [FONT=&quot]Tonsillectomy!

SwitchFX's explanation makes more sense though.
[/FONT]

 

[Sw1tchFX]

 

[Big Mike]

That's right, Through The Lens.

When talking about flashes...TTL has to do with the metering. It means that the camera is measuring the light output of the flash and relaying that information back to the flash.

Modern cameras with E-TTL (Electronic TTL, I think)...will usually fire a pre-flash, the camera measures this test flash and use it to calculate how much flash output to use for the actual exposure. This all happens very fast, you might not even have noticed that the flash went off twice.

 

[three_eyed_otter]

Tax Title & License--C'mon down to Billy Bob's...We've got a good as new Pontiac Fiero

just waitin' to be handled by you!

ldman:

have a good one
3Eo

 

[Sw1tchFX]

that reminded me of this:

NSFW for language.



:lmao::lmao:

 

[Garbz]

Modern cameras with E-TTL (Electronic TTL, I think)...will usually fire a pre-flash, the camera measures this test flash and use it to calculate how much flash output to use for the actual exposure. This all happens very fast, you might not even have noticed that the flash went off twice.

So what's A-TTL. I've always wondered how they differ. I think it's stupid on canon's part not to make them compatible. Nikon call it i-TTL. I guess if apple ever made a camera they'd sue Nikon for the name too.

 

[Big Mike]

So what's A-TTL. I've always wondered how they differ.

A-TTL was the older Canon version wasn't it? Probably Automatic TTL :scratch:
Maybe it was a different type of flash metering...I do know that some flash systems don't work with a pre-flash...but instead they measure the light TTL, during the actual exposure...then when enough light has been recorded, it sends a signal to the flash and the flash is quenched.

 

[Mike_E]

TTL is through the lens as stated. But, TTL auto is where the flash uses a built in sensor to shut itself off when it has received back enough light to properly expose for a set aperture. The cheap ones make you set it on the back and the more expensive ones can tell which aperture is set from the camera. Some of the very best ones only measure the wavelengths that they give off for even more accuracy (I believe the Metz falls into this category).

For true TTL you generally need an OEM flash because the flash and the camera work together as an integrated unit and the manufacturers don't give out the coding.

 

[Big Mike]

But, TTL auto is where the flash uses a built in sensor to shut itself off when it has received back enough light to properly expose for a set aperture

Do they call that TTL...Since is isn't using any of the light that is actually coming 'through the lens' of the camera? I just see those called 'Auto' or 'Auto Thyristor'.

I have always thought that 'TTL' designates that the metering is done by the camera, not by the flash.