Digital Rebel XT - flash sync voltage rating

Started Apr 11, 2005 | Discussions
Doug Kerr Forum Pro • Posts: 20,898
Digital Rebel XT - flash sync voltage rating

Chuck Westfall, Director/Media & Customer Relationship, Canon USA, advises as follows regarding the flash sync circuit of the EOS Digital Rebel XT (EOS 350D):

*****

The EOS Digital Rebel XT uses a modified version of the EOS 20D's shutter unit. Consequently, acceptable trigger circuit voltage for both cameras is the same, i.e., 250 volts. Except for the original Digital Rebel, all current EOS digital SLRs (i.e., EOS-1Ds Mark II, EOS-1D Mark II, EOS 20D and EOS Digital Rebel XT) generate their X-sync signals electronically rather than mechanically. This is why they have higher acceptable trigger circuit voltage ratings than earlier models like the D30, D60, 10D and original Digital Rebel. These older models cannot be modified to achieve a higher trigger circuit voltage rating, since such a modification would require a different shutter mechanism as well as a complete redesign of the supporting circuitry.
*****

Best regards,

Doug

 Doug Kerr's gear list:Doug Kerr's gear list
Leica V-Lux 4
ChrisKrueger Senior Member • Posts: 1,751
Holy carp, Doug!

That's great news! Thanks a lot for posting it here! I have an old Vivitar flash from a Pentax body that I couldn't use with my 300D, but now can with my 350D!

Was that posted on Rob Galbraith's forums, or elsewhere?

-- hide signature --
OP Doug Kerr Forum Pro • Posts: 20,898
You're looking at it!

Doug

 Doug Kerr's gear list:Doug Kerr's gear list
Leica V-Lux 4
ChrisKrueger Senior Member • Posts: 1,751
So, email, then?

Just curious if Chuck is posting elsewhere now. I always kept up on his posts on Rob Galbraith's forum when he was still posting there.

-- hide signature --
OP Doug Kerr Forum Pro • Posts: 20,898
Re: So, email, then?

Yes, e-mail.

No,. I don't think Chuck is regularly posting anyplace. I guess he is too busy with his new responsibilities in his "day job".

It's a shame - we had benefited so much from his regular partciipation in the forum arena.

Occasionally Rob Galbraith will publish a special article to which Chuck has contributed.

Best regards,

Doug

 Doug Kerr's gear list:Doug Kerr's gear list
Leica V-Lux 4
Jurc Veteran Member • Posts: 3,541
Re: Digital Rebel XT - flash sync voltage rating

well, i'll take a mental note not to bug 350D owners with the voltage anymore.

Doug Kerr wrote:

Chuck Westfall, Director/Media & Customer Relationship, Canon USA,
advises as follows regarding the flash sync circuit of the EOS
Digital Rebel XT (EOS 350D):

*****
The EOS Digital Rebel XT uses a modified version of the EOS 20D's
shutter unit. Consequently, acceptable trigger circuit voltage for
both cameras is the same, i.e., 250 volts. Except for the original
Digital Rebel, all current EOS digital SLRs (i.e., EOS-1Ds Mark II,
EOS-1D Mark II, EOS 20D and EOS Digital Rebel XT) generate their
X-sync signals electronically rather than mechanically. This is why
they have higher acceptable trigger circuit voltage ratings than
earlier models like the D30, D60, 10D and original Digital Rebel.
These older models cannot be modified to achieve a higher trigger
circuit voltage rating, since such a modification would require a
different shutter mechanism as well as a complete redesign of the
supporting circuitry.
*****

Best regards,

Doug

-- hide signature --

Nekdo je moral Josefa K. o'crniti, zakaj ne da bi bil storil kaj slabega, so ga nekega jutra prijeli.

ChrisKrueger Senior Member • Posts: 1,751
Re: So, email, then?

Thanks, Doug. It's good to hear he responds to personal emails, at least. Especially one that will be so helpful to us all

How did you ever think to ask if the 350D was more tolerant of high trigger voltages? Because the 20D is? Good catch, however you thought to ask.

-- hide signature --
OP Doug Kerr Forum Pro • Posts: 20,898
Re: So, email, then?

Hi, Chris,

ChrisKrueger wrote:

Thanks, Doug. It's good to hear he responds to personal emails, at
least. Especially one that will be so helpful to us all

I don't press him often, only on things where I think the payoff is really important. (The last time, incidentally, was with regard to the 20D sync voltage limit on theh flash shoe!)

How did you ever think to ask if the 350D was more tolerant of high
trigger voltages?

Three reasons.

1. Because there was no reason to think it was the same as the 10D and 300D.

2. All the recently introduced EOS dSLRs are (see Chuck's enumeration).

3. The language regarding the use of "Non-Canon" flash units in the 350D manual is identical to the language (with regard to the flash shoe) in the 20D manual.

Best regards,

Doug

 Doug Kerr's gear list:Doug Kerr's gear list
Leica V-Lux 4
OP Doug Kerr Forum Pro • Posts: 20,898
Boy, is that a big load off your shoulders or what? (nt)

Doug

 Doug Kerr's gear list:Doug Kerr's gear list
Leica V-Lux 4
ChrisKrueger Senior Member • Posts: 1,751
Re: So, email, then?

Thanks again, Doug! I played around with my "new" old flash last night quite a bit. It's tough getting a full manual flash to take good exposures (especially with my flash unit's bounce flash), but it's fun to play with!

-- hide signature --
dkord Regular Member • Posts: 103
Re: Digital Rebel XT - flash sync voltage rating

Thanks for the info Doug; can you tell me in what article or where I can find the original source?
I'll feel more comfortable telling my friends about it.

 dkord's gear list:dkord's gear list
Canon EF 85mm f/1.8 USM +2 more
dkord Regular Member • Posts: 103
Oh, Never mind.

Sorry missed the part about him answering your email.

 dkord's gear list:dkord's gear list
Canon EF 85mm f/1.8 USM +2 more
OP Doug Kerr Forum Pro • Posts: 20,898
Re: Digital Rebel XT - flash sync voltage rating

Hi, d,

dkord wrote:

Thanks for the info Doug; can you tell me in what article or where
I can find the original source?

The first publication so far as I know is in the post at the head of this thread.

The second publication is here:

http://forums.dpreview.com/forums/read.asp?forum=1031&message=13042207

If you want a more authentic confirmation, you may wish to write Mr. Westfall.

Best regards,

Doug

 Doug Kerr's gear list:Doug Kerr's gear list
Leica V-Lux 4
Tony SD Senior Member • Posts: 2,864
So shutter life on the 350D should be

as good as the 20D?

ChrisKrueger wrote:

Thanks again, Doug! I played around with my "new" old flash last
night quite a bit. It's tough getting a full manual flash to take
good exposures (especially with my flash unit's bounce flash), but
it's fun to play with!

-- hide signature --
-- hide signature --

TonySD

OP Doug Kerr Forum Pro • Posts: 20,898
Re: So shutter life on the 350D should be

Hi, Tony,

Tony SD wrote:

as good as the 20D?

Not necessarily - the 350D shutter isn't the same as the 20D shutter. (Read Brother Westfall's utterance carefully.) It just evidently uses the same basic design (incliidng the fact that it doesn't have any sync contact on it).

I could imagine design details that could make a difference (sort of like the "ball bearings vs. sleeve bearings" differerence in two similar power hand saws).

But I do understand that the 350D shutter is seen as considerably more "durable" than that of the 300D.

Best regards,

Doug

ChrisKrueger wrote:

Thanks again, Doug! I played around with my "new" old flash last
night quite a bit. It's tough getting a full manual flash to take
good exposures (especially with my flash unit's bounce flash), but
it's fun to play with!

-- hide signature --
-- hide signature --

TonySD

 Doug Kerr's gear list:Doug Kerr's gear list
Leica V-Lux 4
AdamT
AdamT Forum Pro • Posts: 58,589
That IS good news !!

The 1D series have always had 250V protection but I didn't expect it from the 20D and 350D after the 6V of the Dxx, 300D and 10D ..

Excellent news, I can finally ditch the stupid Safe Sync I for for the D60 in 2002 with my second camera :)))))

-- hide signature --

Please ignore the Typos, I'm the world's worst Typist

 AdamT's gear list:AdamT's gear list
Canon PowerShot G1 X Panasonic Lumix DMC-GX85
crobinso_canada Senior Member • Posts: 1,343
But doesn't this contradict the White Paper?

I don't understand. Could Chuck have made a slip? The white paper
said 9v didn't it? Why would this info contradict? Any ideas?

thanks,

Chris

crobinso_canada Senior Member • Posts: 1,343
Re: But doesn't this contradict the White Paper?

Hmmm....I can't seem to find it in the white paper now. I guess it wasn't in
there after all. It was Bot Atkin's website that was the source I guess:

"The EOS 20D maximum flash sync voltage is 250v (for both the hotshoe and PC terminal), the Digital Rebel XT maximum sync voltage is 6v"

http://www.bobatkins.com/photography/digital/eos_digital_rebel_xt_vs_20d.html#better

Here's the Rebel XT White Paper:

http://www.robgalbraith.com/public_files/Rebel_XT_White_Paper.pdf

take care,

Chris

crobinso_canada wrote:

I don't understand. Could Chuck have made a slip? The white paper
said 9v didn't it? Why would this info contradict? Any ideas?

thanks,

Chris

OP Doug Kerr Forum Pro • Posts: 20,898
Re: But doesn't this contradict the White Paper?

Hi, Chris,

crobinso_canada wrote:

Hmmm....I can't seem to find it in the white paper now. I guess it
wasn't in
there after all. It was Bot Atkin's website that was the source I
guess:

"The EOS 20D maximum flash sync voltage is 250v (for both the
hotshoe and PC terminal), the Digital Rebel XT maximum sync voltage
is 6v"

Hard to tell where Bob might have gotten that "information". As we know, that scoop is hard to come by.

Do note that even the "6 V limit", as applies, for example, to theh 300D, is rarely well stated by Canon.

I consider the best utterance on that to be Chuck Westfall's, which (and I have to parahrase here) was essentially that "flash sync votages substantially above 6 V may reduce the life of the shutter sync contact."

Best regards,

Doug

 Doug Kerr's gear list:Doug Kerr's gear list
Leica V-Lux 4
Jeff Tabor Regular Member • Posts: 382
I fried my D60 this way

Can it be fixed? I didn't know anything about it when I bought the camera.

Keyboard shortcuts:
FForum MMy threads