Firing 550ex/420ex with pc cord or optical slave?

[dennykyser]

I have the slaves both photo and pc that you can mount a flash on, but do they work with these flashes. I know the basic flash will fire but how about these High tech TTL systems. I remember with my mets 54 I had to order some adapter that made the flash a simple manual flash.

[robertwgross]

(1) Study the Canon system diagram, and note what hooks up to what.
(2) If you want E-TTL operation, stop there.

---Bob Gross---

[slin100]

From what I've heard, the inexpensive optical triggers don't work well with Canon EX flashes. The prevailing problem is that the flash will fire once and the slave will lock up, requiring you to power cycle to flash. Some have had success using the more expensive Wein optical triggers.

Whatever the case, you definitely will lose all ETTL functionality. You'll need a ST-E2 if you want wireless ETTL.

[Morden]

Whatever the case, you definitely will lose all ETTL functionality. You'll need a ST-E2 if you want wireless ETTL.[/quote]
The ST-E2 is a great device. :)

[robertwgross]

The ST-E2 is a great device.

I shot one wedding, and I had used my ST-E2 for something there. I packed all my gear home afterwards and did something else. Three weeks later, there was another wedding, so I was checking my gear out before heading there. I discovered that the ST-E2 power switch had been left ON since the earlier wedding. I couldn't find my spare battery for it, so I did that next wedding using the ST-E2 with suspect battery. A voltmeter showed it had the normal terminal voltage, despite three weeks. I've since located my spare battery, but I'm not going to use it until the first battery actually craps out.

Lithium primary batteries are interesting. The voltage will appear virtually normal for a very long time, and then all of a sudden they go dead. It is not a graceful decay as on other battery chemistries.

---Bob Gross---