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Peter Wallage
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, December 19, 2005 - 02:50 pm: | 
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Hi all,
Can anyone give me a dfinitive answer about using a non-Canon, non-dedicated flash in the hot shoe of a Canon T70?
I have had conflicting advice.
1. Yes you can as long as it on 1/90sec, manual aperture selection.
2. No you can't, it won't synchronise.
3. Any flash except a Canon Speedlight will damage the camera because of the high flash contact current.
All Canon UK will say is that the T70 is designed for Canon flash units and they have no experience of using any other makes.
I don't want to just try it and see in view of amswer 3.
Does anyone know the real answer, please?
Peter |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, December 19, 2005 - 06:42 pm: |
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You are talking about a normal 'hot shoe' flash unit with the single connector in the foot I suppose.
It is not the current only that is the problem but the trigger voltage in electronic and digital cameras. For Canon electronic cameras the trigger voltage of the flash unit must be 6 volts or less. If trigger voltage less than 6 volts then OK to use if you take into account the following:-
When using single contact units place a piece of insulating tape over the small contacts on the camera shoe. Shorting can occur between the centre flash unit contact and the small shoe contacts when the unit is being fitted. more so if unit is on and charged.
Obviously if the unit is non dedicated you have to set shutter to sync speed and set aperture manually. If flash unit is auto it will self regulate output, if not auto unit use the GN/Ft equation or supplied tables.
A bog standard flash with a single foot contact will synchronise at sync setting on camera.
Some flash units with trigger voltages above 6 volts will damage the T70 so you need to know the trigger voltage or purchase a Wein Safety Sync Adapter - basically stops the over voltage.
On another photo site I came across a very comprehensive list of flash trigger voltages, but I did not mark it so cannot refer you to it. Google 'electronic flash trigger voltage comparison' and see what happens. This might be the site www.botzilla.com/photo/strobeVolts.html but I cannot seem to connect.
Canon UK gave me a lot of useful information on T90 and flash units a number of years ago - specifically mentioned trigger voltages of non canon units, especially studio uni |
Peter Wallage
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 11:33 am: |
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Thanks for that really useful info, Glenn. Can I assume that the trigger voltage is the same as the combined series voltage of the dry batteries that charge up the capacitor in a small flash? In other words, if it takes for example two AA batteries in series will the trigger voltage be three volts? If not, is there any way I can measure it with a multimeter?
Thanks,
Peter |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 20, 2005 - 11:56 am: |
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Peter,
From reading the info on that forgotten site, it seems that everybody was using DVM to measure. From what I remember of the listed voltages it has NOTHING to do with the batteries and how they are connected. This is based on me having two of the models listed and thus knowing the power supply, but could be wrong on this.
As to measuring; I assumed that the DVM was connected across the foot or PC contacts and the flash then fired via Test Button. Perhaps this is rather simplistic, but from number of results I cannot see all those people diving into the internals of their flash units. Anyway some of the units are almost un-diveable without spare bits and pieces.
The list was bloody comprehensive and I will see if I can find it again - may link from one of the EOS forums.
Is maker still in existence, perhaps a quick email might get the information.
Glenn |
Doug Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, December 24, 2005 - 07:54 pm: |
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www.botzilla.com/photo/strobeVolts.html site is still active. Good stuff. |
Ben
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, December 26, 2005 - 08:30 am: |
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I measured the sync voltage of my 283 by measuring across the two hotshoe contacts with the flash fully charged. This voltage is the voltage that will surge through the camera's flash trigger as soon as they are closed, so this is the voltage that you need to be concerned with. In my case, I measured 270 volts, so, needless to say, my 283 has not been mounted my on T70. |
Peter Wallage
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 27, 2005 - 04:35 am: |
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Doug,
Many thanks for that link. I looked up in the list the three flashes I have, Sunpak, Starblitz and Metz, and they are all well over the 6v limit given by Canon, so I won't be using them on my T70.
Peter |
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