Subtronic EOS 300D ETTL

Hi,

Just my thoughts on TTL converters based on some information from Matthias Heinrichs. I don’t know how Ikelite’s solution works. But the fact that the Ikelite converter has to be designed for every camera model and adapted to certain existing strobes is to some degree identical to the Heinrichs converter (separate or built into Mini 300D version). So I call them both converters here

I see two drawbacks in difference to third party “real” E/D/-TTL strobes:

1.

third party strobes like Sigma or Metz have implemented a kind of complete and proper TTL protocol. Metz just made a hint: ”the license and protocol information from Canon are naturally not for free to us”. So I guess this means they pay some kind of license fee to Canon (and Nikon, …) but get proper communication protocol details.

The advantage is that the strobes work like an original one and support all cameras which are present of the time the strobe is released.

The converters just own a kind of hacked protocol which will be limited to the camera the hacking was done for.

I can imagine that the electronic handshake between nowadays cameras and strobes (where camera and strobe introduce to each other) is already a problem. So the Heinrichs converter (available for every housing) did a great job with a 300D but didn’t work properly with my 10D.

2.

The preflash item. In difference to digital compact cameras, DSLRs don’t have a normal steady preflash. Canon’s E-TTL has a modulated preflash (intensity is modulated, not steady).

Sigma and Metz strobes have to feature this special preflash as well. So no problem here.

As far as I understand the converters drive the amphibic strobes to fire a steady preflash. The exposure calculation for the mainflash is influenced by this and compensated by the converter with a kind of correction table. Maybe Ike could tell if this is the same with Ikelite’s converter?

To me this would mean that the converters for nowadays amphibic strobes will always suffer in temrs of compability. They have to be adapted to every camera and to some strobes as well. Because it is more a way of hacking instead of implementing the full Canon or Nikon protocol which would work with every E-TTL or i-TTL camera.

So far I didn’t see any results with these converters, if the correction for the steady preflash gives constant good results underwater. 300D topside was OK.

Would be interesting to see one manufacture coming up with a real E/i/D-TTL strobe like the Sigma and Metz landguns. Sea&Sea or Inon?

But this might be difficult. Don’t know if a big ring type flash tube could produce the required preflash with appropriate timings and so on.

I might be completely wrong. As I said I don’t know if Ikelite’s converter is comparable to the Heinrichs model in terms of working method.

But I feel we won’t see this solution very soon: “here is your E-TTL strobe, plug it onto any E-TTL camera and it works like a landgun" (like third party Nikonos V strobes in the past). Same with i-/D-TTL.

Julian

Sorry for late entry to this thread, but just some general comments (maybe a little tirade ) about strobe ratings, and in particular the relevance of “watt seconds” power.

In addition to reliability, after-service, and subjective criteria like color temperature etc., strobes should be evaluated on actual performance.

Watt seconds does not equal performance.

Watt seconds is the “power” (basically, condenser capacity) a strobe has before it fires. When it fires the watt second rating becomes fairly irrelevant. Circuitry design & efficiency; and, reflector design, material and efficiency are what are critical to turn the available energy into useable light.

It does not make sense to have a strobe with a huge watt second spec (with requisite battery & condenser capacity) if much of the power is lost before it reaches the subject. Conversely, if a strobe can efficiently utilize most of the energy, which reaches the subject as light, and the strobe is lighter and smaller as a result, all the better.

Accordingly, watt seconds or “power” should not be used as guiding criteria for evaluating strobes. Instead, actual performance is more meaningful. In particular, Guide Number and Beam Angle are most relevant and practical.

Would someone please conduct an objective and comprehensive test of actual strobe performance? I would hope the results would confirm above thinking.

Best regards,

-Mark Rupert

Inon America, Inc.

We agree with Rupert's comments, but it does take watt seconds of power to produce powerful strobes. Otherwise we would pop in two "AA" cell batteries and produce 400 watt second strobes. Our tirade is about strobes with almost inentical intensity and coverage yet wildly different advertising claims. We have screamed for years about the 90 and 100 degree claims for strobes that have two f/stop loss of inensity at ninety degrees coverage. DS-50 sure looks puny when comparing ad claims with the competition, yet all are surprisingly similar in performance.

A topside guide number with topside beam angle are not pratical at all. We want to use the stobe underwater. To compare two different strobes you'll need:

-power

-color temperature

-weight and buoyancy

-UW guide number together with the used measuring method (e.g. 1 f/stop)

-UW beam angle

-recycle time (For a FULL charge, not the usual 80%....)

-number of full power flashed with one set of batteries or one charge (You can compare the efficiency of the inverter)

-sizes

-electrical/optical "interface"

And some more "soft skills":

-after sales service (if required)

-reliability

-available add-ons

-useability of the controlls

-additional features (like light or audible signals)

-all I missed

moving on ... E-TTL 10D

http://www.digitaldiver.net/yabbse/index.p...y;threadid=9149

Julian