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*idtDs and old flash

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May 8, 2005 11:33:27 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Hi, *istDs-ists, I've been wondering for a long time whether I can use my
very old Canon 155A flash with my very new *istDs...

I have sent a few emails to Pentax. I got one answer (from Pentax Canada,
Pentax USA) and it says:

"I am not able right now to give you the exact voltage in the hotshoe, but I
would not recommend you to use the Canon 155A with camera."

Fair enough, I suppose it's not good for business.

I've removed the sprockets on the Canon 155A hotshoe except of course for
the central one.

I've measured the voltage and fount it to be 5.5V (other people report
8.2-8.7V, 6.04V, 6.5V...)
Pentax (Germany) is reported to have said that the maximum-voltage for
DSLR's *istD + *istDS is 30 Volt Positive in the middle.
BUNG wrote on 8 May that he was told that the *ist-DS is safe for 480V,
1.26A max.

I'm confused. Any feedback welcome.

Regards,

Jean.

More about : idtds flash

Anonymous
May 9, 2005 5:21:44 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

In article <427e4dbe$0$1236$8fcfb975@news.wanadoo.fr>, "JD"
<no.spam.jdon@wanadoo.fr> wrote:

> Hi, *istDs-ists, I've been wondering for a long time whether I can use my
> very old Canon 155A flash with my very new *istDs...
>
> I have sent a few emails to Pentax. I got one answer (from Pentax Canada,
> Pentax USA) and it says:
>
> "I am not able right now to give you the exact voltage in the hotshoe, but I
> would not recommend you to use the Canon 155A with camera."
>
> Fair enough, I suppose it's not good for business.
>
> I've removed the sprockets on the Canon 155A hotshoe except of course for
> the central one.
>
> I've measured the voltage and fount it to be 5.5V (other people report
> 8.2-8.7V, 6.04V, 6.5V...)
> Pentax (Germany) is reported to have said that the maximum-voltage for
> DSLR's *istD + *istDS is 30 Volt Positive in the middle.
> BUNG wrote on 8 May that he was told that the *ist-DS is safe for 480V,
> 1.26A max.

Jean-

No doubt the Pentax answer is correct because they have no knowledge of
the Canon flash.

I don't know of an easy way to measure the peak current of your flash
terminals, but suspect it would be less than the 1.26A value. Flashes
that use a higher voltage across the terminals, require your camera's
contacts to discharge a capacitor into the primary of an ignition
transformer. With only a low voltage to work with, it is probably applied
to an electronic switch inside the flash. Such a switch would absorb the
higher voltage and current needed to excite the ignition transformer when
firing the Xenon flash tube.

If it were mine, I would go ahead and use it.

Fred
May 10, 2005 4:06:52 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

"Fred McKenzie" <fmmck@aol.com> a écrit dans le message de news:
fmmck-0905051321450001@acade566.ipt.aol.com...
> In article <427e4dbe$0$1236$8fcfb975@news.wanadoo.fr>, "JD"
> <no.spam.jdon@wanadoo.fr> wrote:
>
>> Hi, *istDs-ists, I've been wondering for a long time whether I can use my
>> very old Canon 155A flash with my very new *istDs...
>>
>> I have sent a few emails to Pentax. I got one answer (from Pentax Canada,
>> Pentax USA) and it says:
>>
>> "I am not able right now to give you the exact voltage in the hotshoe,
>> but I
>> would not recommend you to use the Canon 155A with camera."
>>
>> Fair enough, I suppose it's not good for business.
>>
>> I've removed the sprockets on the Canon 155A hotshoe except of course for
>> the central one.
>>
>> I've measured the voltage and fount it to be 5.5V (other people report
>> 8.2-8.7V, 6.04V, 6.5V...)
>> Pentax (Germany) is reported to have said that the maximum-voltage for
>> DSLR's *istD + *istDS is 30 Volt Positive in the middle.
>> BUNG wrote on 8 May that he was told that the *ist-DS is safe for 480V,
>> 1.26A max.
>
> Jean-
>
> No doubt the Pentax answer is correct because they have no knowledge of
> the Canon flash.
>
> I don't know of an easy way to measure the peak current of your flash
> terminals, but suspect it would be less than the 1.26A value. Flashes
> that use a higher voltage across the terminals, require your camera's
> contacts to discharge a capacitor into the primary of an ignition
> transformer. With only a low voltage to work with, it is probably applied
> to an electronic switch inside the flash. Such a switch would absorb the
> higher voltage and current needed to excite the ignition transformer when
> firing the Xenon flash tube.
>
> If it were mine, I would go ahead and use it.
>
> Fred

Thanks for your encouragement. I went ahead some time before I read your
advice. I hope there is no damage il the long run.
Jean.
!