What is TTL?

Discussion in 'Photography Beginners' Forum' started by Cero21, Sep 13, 2007.

  1. Cero21

    Cero21 TPF Noob!

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    I've been looking a couple flashes and they all state TTL auto and such like that. What exactly is TTL?
     
  2. Sw1tchFX

    Sw1tchFX TPF Noob!

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    Through-The-Lens
     
  3. gryphonslair99

    gryphonslair99 Been spending a lot of time on here!

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

    SwitchFX's explanation makes more sense though.
    [/FONT]
     
  4. Sw1tchFX

    Sw1tchFX TPF Noob!

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    :D
     
  5. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    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.
     
  6. three_eyed_otter

    three_eyed_otter TPF Noob!

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    Tax Title & License--C'mon down to Billy Bob's...We've got a good as new Pontiac Fiero [​IMG] just waitin' to be handled by you!

    :pig::eek:ldman::twoface:

    have a good one
    3Eo
     
  7. Sw1tchFX

    Sw1tchFX TPF Noob!

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    that reminded me of this:

    NSFW for language.



    :lmao::lmao::lol::lol:
     
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  8. Garbz

    Garbz No longer a newbie, moving up!

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    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.
     
  9. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    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.
     
  10. Mike_E

    Mike_E No longer a newbie, moving up!

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    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.
     
  11. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    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.
     

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