digital TTL versions explained?

I am a bit of a fossil. I have been shooting my TTL strobes on manual for nearly 20 years and only occasionally on TTL for some macro work. Can anyone explain all the new versions of digital TTL?

i.e. eTTL, iTTL, and now Nexus and Inon have got together to bring out sTTL, I know the s stands for slave.

Do the different prefixes refer to different generations?

Do they work differently?

Which ones use preflash?

I prefer hardwired, which are hard wired?

Thanks everyone.

Mary

Hi Mary,

Here is a quick account.

eTTL is Canon's DSLR TTL protocol. There are actually several flavours. I have always assumed that the e stands for EOS, but I'm probably wrong.

iTTL is Nikon's DSLR TTL protocol. Again there are subtle differences between this protocol on the different camera models. Like the Canon system the companies own flashes can cope with these differences. This is not always the case with third part strobes - which sometimes have to be camera specific. I presume the i designation is to make it sound digital and sexy - like the i in iPod?

dTTL was Nikon's early DSLR TTL protocol. The D100 was the last camera to use this. d stands for digital.

sTTL is the system developed by Inon for a optical slaved TTL with system with digital compact cameras. The Inon system is the only one that is not electronically hardwired.

One of the main differences between this and old fashioned TTL (Nikonos style) is that the digital systems use preflashes (although it should be noted that preflashes were also used in the later film TTL protocols).

Alex

p.s. All that is written from memory - so please don't treat it as gospel. I haven't checked my facts for a while!

For the record, eTTL = evaluative TTL

As Alex mentioned, it's not exclusive to Digital SLRs, in fact quite a number of the Canon EOS film cameras support it, including EOS 3 and EOS 1V (all of what Canon refer to as "Type A" bodies). It benefits from using the same exposure sensors as the ambient metering system, whereas TTL sensors are generally less sophisticated.

Martyn

Thanks guys,

Mary