flash e-ttl su analogiche?

“ la EOS 50 è stata la prima Canon a utilizzare il sistema E-TTL, quindi in teoria dovrebbe funzionare senza problemi „

“ TTL and E-TTL and EOS film cameras.

Most film-based Canon EOS cameras support TTL flash metering. The exceptions are the latest consumer EOS film cameras and the oddball Canon EF-M. (the EF-M was a manual-focus camera that could accept EF-mount lenses but which lacked both autofocus and TTL flash circuitry as a cost-saving measure; you had to buy an optional flash unit with an external sensor, the Speedlite 200M, if you wanted to do flash photography with the EF-M) Those film-based EOS cameras with built-in flash units and TTL support rely solely on TTL for flash exposure control of those internal flash units.

Canon cameras designed prior to the Elan II/EOS 50 of 1995 don't support E-TTL. With the release of this camera Canon divided their camera bodies into two types - A and B. Type A bodies are bodies which support E-TTL, FEL and FP flash technologies. Type B bodies are bodies which do not.

With flash units it's easy - if the name of the flash unit ends with the letter X (eg: 550EX, MT-24EX) then it's an E-TTL unit. If it ends with anything else (eg: 430EZ, 480EG) then it is not.

However, there are three points of note here. First, Canon continued designing and selling type B bodies for many years after the introduction of the Elan II/EOS 50, such as the EOS 3000 and venerable EOS 5/A2, so the date you bought your camera won't determine if it's a type A or B body. Second, since Canon came up with the whole A/B naming convention in 1995, older cameras are obviously not described as being "type B" in their manuals. And third, type A simply means support for E-TTL, FEL and high speed sync - it doesn't mean that the camera necessarily supports other recent flash features such as wireless flash ratios or modelling flash.

So the upshot of all this is the following:

TTL/A-TTL and E-TTL are incompatible flash metering systems which can't be combined in any way. Some film cameras support both technologies, but you can't use them simultaneously.

All EX-series (ie: E-TTL capable) flash units also support TTL metering and automatically revert to TTL metering when used with an older type B camera body. However, no EX-series flash units support A-TTL metering.

Since virtually all EOS film cameras (all type B and nearly all type A bodies) support both TTL and A-TTL metering they can all use E-series flash units in TTL mode and EZ-series flash units in A-TTL mode. All EOS digital cameras support either E-TTL or E-TTL II, depending on when they were designed (see below).

If both the camera and flash unit support E-TTL (ie: the camera is a type A body and the flash an EX series) then they will use E-TTL unless specifically overridden (see "disabling E-TTL" below).
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