What is so complicated about iTTL?

With so many manufacturers coming up with support for Canon's eTTL (Ikelite, Aquatica, Inon, Sea&Sea), I wonder what is so complicated about Nikon's iTTL since nobody has produced (hell, they are not even talking about it) anything compatible yet...

POSSIBLE Answers.

1. iTTL is newer. Canon eTTL came out on the Rebel before iTTL appeared on the D70.

2. eTTL is more important because the Canon Rebel and 20D cameras are perceived to be better/more popular DSLRs for underwater photography.

3. iTTL is tougher to implement than eTTL.

many manufacturers coming up with support for Canon's eTTL (Ikelite, Aquatica, Inon, Sea&Sea

Inon does not have any E-TTL solution. They offer common Nikonos strobes, that's it. Inon's "optical TTL feature for DSLR" is so much around as their 10D housing (hoho )

Aquatica never finalized their ICU from what I’ve heard/seen? Or has somebody a working unit now?

Two converters available which do not offer the exposure precision and compatibility of a real E-TTL system (expecting offense for this 8). but please including reasonable explanation than advertising :wink: ):

1. Ikelite for Ikelite housings and two Ikelite strobes for the corresponding cameras (10D,20D,300D ??)

2. Matthias Heinrichs (10D, 300D) for several strobes (Ikelite, Sea&Sea, Inon, Subtronic, ….)

These converters are not 100% E-TTL compatible. They are limited to certain camera models as they do not feature the origin Canon protocol chip. And even with the limited compatible cameras they work different to E-TTL.

Only real E-TTL strobe is the Mickey Mouse YS-55 from Sea&Sea which has less power and coverage than a good housed landgun. In difference to Ikelite and Heinrichs you can plug this ridiculous strobe onto every E-TTL and E-TTL II camera like an old 1995 Canon landgun which works with a brand new 20D 10 years later as well.

Canon eTTL came out on the Rebel

E-TTL was not introduced with the 300D. E-TTL was introduced in 1995 and is 100% up-/downwards compatible over the whole period. Manufactures often want to make you believe E-TTL II is different in terms of strobe control that they can advertise “hey, we even support E-TTL II”. E-TTL II is just a software feature of the camera taking subject distance into consideration, etc.

Only for Ikelite and Matthias an E-TTL II camera is different and means additional hacking. But not because of E-TTL II itself. They have to hack it for every new camera model as they both do not have the proper E-TTL protocol implemented as Sea&Sea has got (they seem to have a good line to arrogant Canon Japan. They don’t give such details and protocol chips away easily)

From my understanding i-TTL features multiple preflashes. E-TTL just one. But the intensity is modulated (therefore all conversion units never work so exactly as the original E-TTL).

Different to Nikon: Canon has not changed it’s E-TTL system for the last 10 years which is nice.

Some suppositions why i-TTL conversion is not available already:

- multiple preflashes can not be fired by amphibic strobes. Hard for a conversion unit to equalize the exposure differences because of one steady preflash instead of the stroboscope i-TTL preflash

- if intention is to reproduce the multiple preflash the current amphibic strobes are to slow (I still doubt a big ring tube can be as fast as required)

- I guess manufactures became upset when they started to figure out D-TTL and Nikon switched once more to i-TTL. Maybe it was more promising to focus on Canon’s E-TTL which has greater lifetime than a Nikon TTL system nowadays (I just remember D100 landguns have been exchanged for D70 compatible ones)

Just my ideas on this topic

Julian

"Two converters available which do not offer the exposure precision and compatibility of a real E-TTL system (expecting offense for this . but please including reasonable explanation than advertising ): "

Compatibility yes, but I thought the Ikelite exposure precision was pretty good from what I've seen - any reason to think it's not? This is important to me as I plan to update my non-eTTL housing, which isn't particularly cheap, and involves me having no housing for several weeks. Other issue is whether eTTL2 implimentation works better than eTTL (given that each camera is different) and whether it is therefore easier/more cost effective to trade 10D and 10D housing for new 20D and 20D/ettl housing.

Is the Mathias converter living up to your expectations?

Amphibic strobes do not output a modulated preflash like your 420EX does. This causes exposure differences which a converter's logic has to equalize. That does not mean the converters do not work in real world. But they work different to real E-TTL strobes and landguns.

Rob, I would go for it if you want to have automatic strobe control, because you have no other choice. Or wait for Sea&Sea until they bring out the YS-55's big brother and have a modified sync cord for it :-)

Why would you suggest a better performance from a 20D? Same story here.

I've posted samples from the Heinrichs converter with a 300D:

http://www.wetpixel.com/PNphpBB2-viewtopic...-start-15.phtml

I've never seen such exposure series from Ikelite's converter, only some shots from a Dealer here in wetpixel. I think they were without EXIF data in did not really show how the system performs. I my opinion all those converters (no matter if Ikelite or Heinrichs) are still a compromise in comparison to a real E-TTL strobe. But if I would have an Ikelite housing already I would order the conversion of course.

Having that said, I have a converter in my housing as well.

It delivers similar results as the 300D photos linked above.

But I have trouble to get the Z220 focus light and laser supported that they are driven by the camera's trigger pressed halfway down :-)

However, I can switch them on manually and they will be surpressed when the strobe fires which is OK.

Only with wide open apertures the converter delivers slightly overexposed results which Matthias has confirmed. Not visible in the results linked above because they were done with the kit lens in tele position (slow lens, begins at 5.6). Maybe Matthias did not have any other lens when adjusting the unit

Julian