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TTL Flash

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Ravi Krishnaswamy

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Dec 8, 1993, 3:20:05 PM12/8/93
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Hello Folks,

I have read a lot of posts about TTL flashes. Believe me, I have
one with TTL mode(Nikon SB2X). But, I am anxious to find out
what TTl stands for and how it is different from other modes
(manual and auto). When does one use the TTL mode compared to
others.

I read my manual, and not able to figure out the definition of TTL
and its advantages (or the disapdvantages) over the other modes.

Any reponse/info would be greatly appreciated.

Ravi

Paul Tse

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Dec 8, 1993, 10:59:26 PM12/8/93
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In article <CHqGH...@lznj.lincroftnj.ncr.com>,

Ravi Krishnaswamy <ra...@sodium.lincroftnj.ncr.com> wrote:
>
>I read my manual, and not able to figure out the definition of TTL
>and its advantages (or the disapdvantages) over the other modes.

TTL stands for "through the lens" and refers to the metering of the
flash exposure. In TTL mode, the flash output is cut off when the
meter inside the camera body sees that enough light has reached the
film. This automatically takes into account any filters and lens
extensions you have on.

The other auto mode would be using the metering cell on the flash
unit. This eye does not necessarily see the same angle of view
as the lens you have on the camera; and it does not automatically
take into account filters, etc.

Given that you've got TTL, you would probably use it all the time.
The only time you'd want to use the flash's sensor is if you're
using the flash off camera (remote triggered) and don't have a
dedicated flash extension cord (in your case, the expensive SC-17).

Hope this helps.

~{@O>F~}

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Dec 10, 1993, 12:15:45 PM12/10/93
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: using the flash off camera (remote triggered) and don't have a
: dedicated flash extension cord (in your case, the expensive SC-17).

Does anybody know any third-party cord as a substitute of SC-17?

-- Yi

Craig Greenwood

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Dec 13, 1993, 1:40:39 PM12/13/93
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===========================================================================

"TTL" stands for "Through The Lens". In this mode the flash employs a sensor
that is built into the camera body to sense when enough light has been
delivered from the strobe. If you open the back of the camera and hold the
shutter open (using "B" setting on shutter speed dial) you will see a sensor,
maybe with some sort of lens, on the bottom or side of the mirror box. This
sensor cell reads the light that is being reflected off the film itself.
Because of how it reads the light, the focal length, aperture, and any filter
factors are included. This makes it ideal for macro because bellows factor
just is not an issue anymore.

Craig

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