The Canon EOS and Photography Forums

I have read that one has to be careful using some flashguns with the Canon EOS cameras because the trigger voltage can fry the electronics, if connecting via the hot shoe.  I have been told that if one connects to the camera using a synch cord and the PC terminal socket then the trigger voltage is not an issue.  I plan to use a Metz 45 CT-1 with a 40D connecting via the PC terminal socket..  Is this a no-no?

The maximum sync voltage on the EOS 40D is 250v, and that applies to both the hot-shoe and the PC connector. Some earlier models had a maximum sync voltage of 6v.

If you are in any doubt about the sync voltage of the Metz (or any other flash), you can always use a Wein Safe Sync (http://www.amazon.com/exec/obidos/ASIN/B00009UU18/bobatkinsphotogr) which fits in the hotshoe, provides a PC connection and a hotshoe connection and converts any flash sync voltage up to 400v down to 6v for the camera. That means you can use just about any flash even with early EOS bodies with only a 6v sync rating.

As far as I know the following information is correct, but use it at your own risk!

Canon DSLRs safe for sync voltages up to 250 volts:
EOS-1D Mark II N, EOS-1D Mark II/III, EOS-1Ds Mark II/III, EOS-1D, EOS-1Ds
EOS 30D, 20D, 5D, 5D MkII
EOS Digital Rebel XTi, XT (400D/350D)
EOS D6000/D2000, Kodak DCS560/DCS520
EOS-DCS series

Canon DSLRs safe for sync voltages up to 6 volts:
EOS 10D, D60, D30
EOS Digital Rebel (300D)

As far as I know, the maximum voltage rating is the same for both the hotshoe and PC terminal in all cases.

Of course using such a device (or the PC socket) means that flash exposure must be manually controlled (via the aperture and ISO rating using the flash Guide Number).

I don't know what the sync voltage of the Metz CT-1 is, but if it's under 250v you should be OK with it on the EOS 40D.

Thanks Bob, I think I have suficient cause to invest in a Canon flashgun that will be safe.
Ken