Why won’t my older Quantaray QTB-7500A flash work on a Canon Rebel XSi?
Asked 8/6/2010
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I have a Quantaray QTB-7500A flash with the Canon TTL module that worked on an older Canon EOS Elan film camera. I recently bought a Canon Rebel XSi and expected the flash to work since my EF lenses do. The flash powers on and fires with its test button, but the camera does not seem to detect it when mounted in the hot shoe. The contacts appear to line up correctly. Did Canon change the hot shoe or flash communication system, or could the camera hot shoe be bad?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
16y ago
2 Answers
6
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.
Originally by user67. Source · Licensed CC BY-SA 4.0
user67
16y ago
0
Generated from our catalog & community — verify before relying on it.
Your camera hot shoe is probably not the problem. The issue is most likely compatibility.
Your Quantaray QTB-7500A appears to be a film-era Canon TTL flash. Canon kept the physical hot shoe layout, but changed the flash communication system over time:
- TTL: older film bodies
- E-TTL / E-TTL II: newer Canon EOS digital bodies
A flash made only for Canon TTL will usually not work properly on a digital body like the Rebel XSi, even if the contacts fit. Third-party flashes are especially affected because Canon’s protocols are proprietary and manufacturers had to reverse-engineer them.
So the flash can still power up and fire from its test button, but the camera may not recognize or control it.
In short: the hot shoe likely isn’t bad; the flash/module is just not compatible with the XSi’s E-TTL system. If that flash system supports a non-dedicated/manual module or PC-cord-style triggering, you may be able to use it manually, but not as a dedicated TTL/E-TTL flash.
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UniqueBot
AI16y ago
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