AJUTOOOOR!

salut ... am un canon EOS 350D
am cumparat un blitz  speedlite 540 EZ
la probrat si nu da randament .. exista niste setari speciale .. imi iese cam intunecat .. ba e prea puternica .. ba prea slaba lumina .. nu stiu ce sa zic .. sau poate ca nu se potriveste cu canonu .. aveti vreo idee .. un sfat ceva .
nu sunt profesionist ..dar vreau sa am cat de cat habar de fapt .. sunt paralel

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TTL - With film SLR cameras, light passed through the lens and reflected by the film is continually measured by the flash sensor during exposure until the correct exposure has been achieved. This system is referred to as a TTL flash metering system (see the image of a TTL flash sensor system below).

D-TTL - Digital camera sensors do not reflect enough light for the TTL sensor to use during exposure so metering is performed using light from the *Monitor pre-flash reflected from the shutter curtain before the exposure, the end of the exposure is detected by the camera metering system. This system is referred to as a D-TTL flash metering system.
*What is ''Monitor pre-flash' (or 'pre-flash')?
The Speedlight fires a series of pre-flashes to 'test' the scene, using the flash meter it can then calculate exposure just before firing the main flash to illuminate the subject during the actual exposure time. The pre-flashes are lower power than the main flash. Nikon use the term DX as a suffix for Speedlight names that support the pre-flash function which is an essential element of D-TTL operation.

i-TTL - Is an evolution of D-TTL that incorporates more accurate systems for pre-flash. Metering is performed using light from the pre-flash reflected from the shutter curtain before exposure as with D-TTL. However the pre-flash fired is much stronger and of much shorter duration than D-TTL to achieve greater accuracy using the flash sensor.

i-TTL Speedlights are compatible with Nikon's Creative Lighting System (CLS) when used with compatible Digital SLR cameras (D2H and D70) offering new functionality that is not compatible with non i-TTL Speedlights.

What is the difference between TTL, A-TTL, E-TTL and E-TTL II flash?

    These four modes are all forms of through-the-lens flash metering used by Canon cameras. Older EOS film cameras support TTL and A-TTL metering only. Newer film models and all digital EOS cameras support E-TTL flash metering. E-TTL II is available on EOS cameras from 2004 on.

    * TTL (through the lens) and A-TTL (advanced through the lens) flash metering rely on small flash sensors inside the camera body. Flash metering occurs after the shutter has been opened - the sensors record the amount of flash-created light returning to the camera through the lens and automatically shut off (“quench”) the flash when an appropriate amount of light has been produced.

    * A-TTL adds a preflash (a brief pulse of light, usually invisible infrared, from the flash) which is fired before the shutter is opened. This preflash is used in P mode to adjust lens aperture, but that’s really about it. In fact, A-TTL flash still relies on the TTL sensor to quench flash output after the shutter has opened. Sadly, therefore, A-TTL is a fairly pointless flash mode.

    * E-TTL (evaluative through the lens) is quite different. It relies on the standard evaluative metering sensor used in ambient light metering. With E-TTL flash a visible-light preflash is fired by the flash unit before the shutter is opened. The camera records the effects of this preflash and uses it to calculate the appropriate flash output to be delivered once the shutter has opened. E-TTL flash does not use a separate TTL flash sensor, and no metering of flash occurs after the shutter has opened.

    * E-TTL II is a variant of E-TTL. It’s essentially the same as E-TTL but with two main refinements. First, rather than relying on a flash metering pattern it examines the scene before and after the preflash is sent, reducing the risk of highly reflective objects messing up the flash metering. Second, it can incorporate focus distance data from compatible lenses into the metering formula, which can also lower the chances of bright areas causing metering errors. E-TTL II camera bodies can use all E-TTL flash units without problem.

    Remember that to take advantage of a given flash technology you need a camera and a flash which both support the flash technology you want to use. So if you have, for example, a camera body capable of supporting E-TTL and then you attach it to a flash unit which supports TTL but not E-TTL then you won’t be able to use E-TTL.

    For more information on these modes and how they affect your photography please consult my Canon EOS flash photography article.