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Old 4th of November 2006 (Sat)   #1
TMR Design
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Default Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

I know this is a really basic question but I never really see this explained so whenever I see one of these abbreviations being used I am not sure what the distinction is between them.

Can someone give me the rundown?
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Old 4th of November 2006 (Sat)   #2
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

Check out this link.
Look down in table of contents.
http://photonotes.org/articles/eos-flash/
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Old 4th of November 2006 (Sat)   #3
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

TTL is an abbreviation for "through the lens". In a nutshell, TTL flash metering is a concept used by many camera manufacturers with film, measuring light reflecting off the film and shutting off the flash "in real time" as the exposure occured. A different system was required for digital cameras, and Canon refers to its version as E-TTL. Enhancements were made a few years ago and the enhanced version they call E-TTL II. E-TTL in its various forms uses a preflash to calculate the necessary flash power required before the shot is taken.

I highly recommend reading the link PeaPicker provided. It's a bit long, but very enlightening if you want to understand Canon's flash systems.
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Old 4th of November 2006 (Sat)   #4
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

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Originally Posted by PeaPicker View Post
Check out this link.
Look down in table of contents.
http://photonotes.org/articles/eos-flash/
Thanks Jon,

I just read a majority of that link. It helped quite a bit.
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Old 5th of November 2006 (Sun)   #5
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

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Thanks Jon,

I just read a majority of that link. It helped quite a bit.
Right before I noticed your post I just happened to enter "flash photography" on "The Google" and this site came up.
I learn something new here everyday.
Remembering it is the problem.
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Old 6th of November 2006 (Mon)   #6
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

E-TTL is a variant of ETTR.

ETTR means Expose To The Right, and is a method of using the histogram to get correctly exposed shots. The right side of the histogram represents the brighter pixels -- by exposing to the right, you get a nice, bright image.

E-TTL means Expose To The Left, and is canon's patented flash system designed to produce left-shifted histograms, giving underexposed flash shots.

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Old 6th of November 2006 (Mon)   #7
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

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E-TTL means Expose To The Left, and is canon's patented flash system designed to produce left-shifted histograms, giving underexposed flash shots.
That explains a lot!
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Old 6th of November 2006 (Mon)   #8
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

Quote:
Originally Posted by DavidEB View Post
E-TTL is a variant of ETTR.

ETTR means Expose To The Right, and is a method of using the histogram to get correctly exposed shots. The right side of the histogram represents the brighter pixels -- by exposing to the right, you get a nice, bright image.

E-TTL means Expose To The Left, and is canon's patented flash system designed to produce left-shifted histograms, giving underexposed flash shots.

Heheh...Never thought of it that way.
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Old 6th of November 2006 (Mon)   #9
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

http://photography-on-the.net/forum/...ghlight=ettlii
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Old 6th of November 2006 (Mon)   #10
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

Scott, welcome back, haven't heard from you in a long time. you've always been really helpful, especially on the topic of flash.
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Old 7th of November 2006 (Tue)   #11
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

Thanks. I even got a new trench coat.
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Old 7th of November 2006 (Tue)   #12
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

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Thanks. I even got a new trench coat.
OK, zip it up and get on with business......
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Old 7th of November 2006 (Tue)   #13
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

Quote:
Originally Posted by DavidEB View Post
E-TTL is a variant of ETTR.

ETTR means Expose To The Right, and is a method of using the histogram to get correctly exposed shots. The right side of the histogram represents the brighter pixels -- by exposing to the right, you get a nice, bright image.

E-TTL means Expose To The Left, and is canon's patented flash system designed to produce left-shifted histograms, giving underexposed flash shots.

While this is a clever (and often accurate) description of the acronym the actual description is Evaluative Thru The Lens. The II added recently denotes a new version that in its mystery is probably darker than David's explanation above.

Evaluative - that pre-flash that is quite often not seen - is used to evaluate the scene.

TTL - it's done thru the lens by the camera as opposed to on the flash.
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Old 5th of February 2007 (Mon)   #14
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

I've always been very frustrated by flash photography, but thanks to this thread it's actually starting to make sense! It really does make a difference when you know how your camera is thinking and I've actually managed to capture my first shot using fill flash. I know it's not great, but it's a start!

The only thing that I'm still unsure about is colour temperature. If you're using fill flash then you have a mixture of colour temps, what should you use as the white balance? Or, is it best to sort it out when you process your raw file?
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Old 5th of February 2007 (Mon)   #15
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Default Re: Can someone please explain what exactly TTL, E-TTL and E-TTL II mean?

Set the WB to the ambient color temp, and match up the flash by using a color gel.
Matching up mixed lighting in post is nearly impossible.
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