Why doesn't my Sigma EF-500 flash work properly with my new Canon 60D?

Question

I've recently upgraded to a 60D (from a 300D) and have just tried my Sigma EF-500 DG ST flash. This used to work fine on the 300D but on the 60D when using it in TTL mode the flash defaults to the setting for 105MM, when focusing to take the picture the flash moves through the range down to 28mm and then back up to 105mm which it then sticks on. Trying to take another picture the flash then does the same again. I've got the EFS17-85mm lens fitted to the body.

Any ideas as to what the problem might be? At the moment all the test pictures I've taken are blown out because the flash is too strong. I can revert back to Mh or Ml modes or bounce the flash off a wall or ceiling but I'm confused as to why the flash isn't working when using in the typical configuration like it used to. Does the communication protocol between body and flash change depending upon the model of camera; is my 60D unable to drive the flash?

Given that it's Xmas eve, bit late to ask for another present!

Answer 1

Contact Sigma. They don't license the flash protocol; they reverse-engineer it. That means that they don't always get the details exactly the same a Canon, and quirks in new models often require an update. The official protocol (secret to Canon) probably hasn't changed, but different camera bodies can implement it differently, and so not work with older reverse-engineering. That's probably what is going on. In the US, Sigma will do such updates for free:

Courtesy Updating

In today's day and age of ever-changing technology, Sigma will, at our discretion, offer some updates if available to the original purchaser of the equipment at no charge.  These updates are done as a courtesy and are not considered warranty repairs.  

(You will have to send it in the their service center, and it may take a little while to get it back.)

I'm not sure of the situation in the UK; I can't find an equivalent message on the Sigma UK site, but there they discuss a specific compatibility issue and say that they'll fix it for free under warranty, for £5 out of warranty with proof of purchase, or £34 for second-hand items. I'd contact them and see if this is also the case with EF-500DG updates.