Why does my old Quantaray flash not work on my newer Canon DSLR?

Question

I have an older Quantaray QTB-7500A flash with the Canon TTL module. I used this with my old Canon EOS Elan 35mm which died a few years back. I recently bought a Canon Rebel XSi, because I could use my old EF lenses, and figured the Flash would also work. However, when I mount the flash on the camera, it does not acknowledge that the flash is there. The flash powers up, and if I hit the test button, the flash fires, so I know the bulb/charging system is OK. The TTL connectors on the flash look like they match the connectors on the Camera's Hot shoe. Am I missing something? Is the Hot shoe bad? Has Canon changed the TTL connector over the years?

Asked by BillN

Answer

There is an in-depth post about Canon TTL here.

The short version is that there is TTL (film/old style), E-TTL (early digital), and E-TTL II (recent digital).

Some new flashes will work with older systems, but flashes designed for TTL are not fully compatible with either version of E-TTL. According to canon-eos.webuda.com, the Quantaray QTB-7500A is only compatible with TTL.

Answered by chills42

Check more discussion of this question.