Help - 450D only fires remote flash on sync cord if popup flash is on

Started Jul 29, 2009 | Discussions
bestremera
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Help - 450D only fires remote flash on sync cord if popup flash is on
Jul 29, 2009

Troubling problem for which there is no apparent solution.
Please help.

I'm firing an off-camera Vivitar 285 using a PC hotshoe adapter and sync cord.
I can fire the Vivitar when I push the test fire button on the hotshoe adapter.

But the flash will NOT fire after I depress the shutter UNLESS the popup flash is up and also fires.
I do not want to use the popup.

Yes, I could cover it up so it doesn't affect the exposure, but I can't understand why this is not working as it is supposed to.
I've tried every menu option there is and no luck.

Can somebody help?

Thanks, Bob

WilbaW
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Re: Help - 450D only fires remote flash on sync cord if popup flash is on
In reply to bestremera, Jul 29, 2009

My guess is that you have a malfunction with the switch in the hot shoe that tells the camera that an external flash is mounted.

If you look into the hot shoe, on one side you will see a metal strip that is pushed down when a flash is mounted. The strip presses on a switch. If that's not working right or not being depressed sufficiently, the external flash won't fire.

This link was posted recently in another thread ( http://forums.dpreview.com/forums/readflat.asp?forum=1031&message=32520357 ), and will give you some more information - http://www.conraderb.com/flashrepair/ .

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Guerito
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Re: Help - 450D only fires remote flash on sync cord if popup flash is on
In reply to bestremera, Jul 29, 2009

It is probably a voltage issue. You can damage your camera if the flash trigger voltage is too high. On Botzilla, the Vivitar 285 is rated at 350 volts, the 285HV is somewhere around 6-8 volts. I believe your hot shoe is rated for 6 volts and your manual warns against connecting a high-voltage flash to the hot shoe (page 167).

Do some reading on this site before you continue using that flash on your camera.
http://www.botzilla.com/photo/strobeVolts.html

Don

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Paul De Bra
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That does not explain the malfunction. The switch is more likely.
In reply to Guerito, Jul 29, 2009

The high voltage means the flash is unsafe, but still it should be triggered.

The hotshoe should trip the switch that tells the camera there is a flash connected to the hotshoe.

Easy way to tell: set the camera on auto in low light and half-press the shutter release button. If the built-in flash pops up it means the camera is not detecting the hotshoe adapter.

Guerito wrote:

It is probably a voltage issue. You can damage your camera if the flash trigger voltage is too high. On Botzilla, the Vivitar 285 is rated at 350 volts, the 285HV is somewhere around 6-8 volts. I believe your hot shoe is rated for 6 volts and your manual warns against connecting a high-voltage flash to the hot shoe (page 167).

Do some reading on this site before you continue using that flash on your camera.
http://www.botzilla.com/photo/strobeVolts.html

Don

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bestremera
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Re: That does not explain the malfunction. The switch is more likely.
In reply to Paul De Bra, Jul 29, 2009

Hi,

The Vivitar is the 285 HV, the 'safe voltage' variety.

Paul, I did your test, focusing and half-press shutter in low light in Auto mode.
The popup flash, popups up.

So the camera is NOT recognizing the hotshoe. But why does the camera send the signal to through the hotshoe only when the popup fires?

Also, is there a forum or Canon tech support where I can document this problem and seek additional Canon help.

Thanks for the help.
Bob

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Guerito
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Re: That does not explain the malfunction. The switch is more likely.
In reply to Paul De Bra, Jul 29, 2009

Paul De Bra wrote:

The high voltage means the flash is unsafe, but still it should be triggered.

The hotshoe should trip the switch that tells the camera there is a flash connected to the hotshoe.

Not necessarily. To protect the camera from damage when using a high-voltage flash, the camera's protection circuit may prevent the flash from firing.

From the camera's instruction manual on page 167:

"Do not attach a high-voltage flash unit on the camera's hot shoe. It might not work."

Going through the poster's history, I see he's had this problem for months now.

Don

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Paul De Bra
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Here is why it does not fire.
In reply to bestremera, Jul 29, 2009

When the camera does not detect an external flash (because the little switch in the side of the flash socket is not tripped) and the internal flash is not popped up the camera "thinks" there is no flash, so it does not try to trigger a flash.

When the flash is popped up the camera knows there is a flash (the internal one) and it triggers that flash. Apparently the trigger for internal and external flash just work in parallel so the undetected external flash still fires.

So really you need to make the little almost hidden switch work, and when it works the internal flash will not pop up in auto mode, so that's the way to check whether it works.

bestremera wrote:

Hi,

The Vivitar is the 285 HV, the 'safe voltage' variety.

Paul, I did your test, focusing and half-press shutter in low light in Auto mode.
The popup flash, popups up.

So the camera is NOT recognizing the hotshoe. But why does the camera send the signal to through the hotshoe only when the popup fires?

Also, is there a forum or Canon tech support where I can document this problem and seek additional Canon help.

Thanks for the help.
Bob

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Slowly learning to use the 450D and and the Canon G6.
Public pictures at http://debra.zenfolio.com/ .

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bestremera
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Re: Here is why it does not fire.
In reply to Paul De Bra, Jul 29, 2009

Maybe I should have mentioned that I never shoot in Auto, only Manual or AV.

Paul, how do I identify this 'hidden switch' and if I find it, how do I make it work?
Thanks
Bob

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Steve Dudley
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Re: That does not explain the malfunction. The switch is more likely.
In reply to Guerito, Jul 29, 2009

I do not understand what is meant by the "flash is unsafe" is that for the user or people nearby or maybe the camera might be damaged. I think if Canon is not recommending the use of high voltage flashes there is a good reason and they have said it might not work in the instruction book and they appear to be right. To the OP don't bother looking for a hidden switch because it is probably hidden for a reason it appears. I think that after three months of looking for a fix the best one is to is to put the vivitar aside and buy a Canon flash that will work .

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Paul De Bra
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A high voltage flash is unsafe for both.
In reply to Steve Dudley, Jul 30, 2009

If you turn on an old high voltage flash while it is not on the camera and you then tough the metal base and the center trigger point you get a serious jolt. (I never tried to find out.)

When the flash is fired the camera briefly shorts the two contacts, which releases the charge built up in a capacitor to the flash bulb. Some electronic circuit in the camera has to short two leads with a few hundred volts between them. Some cameras can handle this, others cannot. (The old DRebel/300D for instance can die when you try this.)

Steve Dudley wrote:

I do not understand what is meant by the "flash is unsafe" is that for the user or people nearby or maybe the camera might be damaged. I think if Canon is not recommending the use of high voltage flashes there is a good reason and they have said it might not work in the instruction book and they appear to be right. To the OP don't bother looking for a hidden switch because it is probably hidden for a reason it appears. I think that after three months of looking for a fix the best one is to is to put the vivitar aside and buy a Canon flash that will work .

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Paul De Bra
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I'm only suggesting "auto" as a test.
In reply to bestremera, Jul 30, 2009

In manual or Av the camera will never automatically pop up the flash. I suggested setting the camera to auto because then it automatically pops up the flash, which is a telltale sign that the camera has not detected the external flash (or flash trigger).

If you take a close look at the "rails" of the flash mount you see that there is a metal strip that is bent down when you insert a flash (or flash trigger). On the left you may see a tiny hole underneath, more or less in the middle. On the right you should see a tiny pin, more or less in the middle. The metal strip being bent down when you insert the flash pushes the pin down, and that is the switch through which the camera detects that a flash is connected.

So put your camera on auto. Half-press, and the flash should pop up. Push it back down. Now insert something in the right flash guide rail (like a small screwdriver or a coffee stirrer) to push down the metal strip and trip the switch. Now half-press the shutter release button again. The flash should not pop up. If it pops up then the switch must be broken. If it does not pop up now, but it does when you insert your flash trigger, it means the trigger is too thin on the righthand side and does not push down the metal strip far enough.

bestremera wrote:

Maybe I should have mentioned that I never shoot in Auto, only Manual or AV.

Paul, how do I identify this 'hidden switch' and if I find it, how do I make it work?
Thanks
Bob

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Slowly learning to use the 450D and and the Canon G6.
Public pictures at http://debra.zenfolio.com/ .

 Paul De Bra's gear list:Paul De Bra's gear list
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bestremera
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Re: I'm only suggesting "auto" as a test.
In reply to Paul De Bra, Jul 30, 2009

Thanks for all the tips.
I'll give the hidden trigger a look.

Steve, of course I've looked into the 430EX but since I only use the flash off-camera, behind an umbrella for portraits, just don't want to spend the extra $240 or so when I SHOULD (big question there) be able to use the Vivitar.

Thanks all. Bob

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Steve Dudley
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Re: I'm only suggesting
In reply to bestremera, Jul 30, 2009

bestremera wrote:

Thanks for all the tips.
I'll give the hidden trigger a look.

Steve, of course I've looked into the 430EX but since I only use the flash off-camera, behind an umbrella for portraits, just don't want to spend the extra $240 or so when I SHOULD (big question there) be able to use the Vivitar.

Thanks all. Bob

I also have a Sunpak flash that I tried to do the same with and finally gave up.

If you want to do some flash portrait work get the 430 ex and a diffuser like the Joe Demb Flipit or the UBC you will be amazed at the results you can achieve by bouncing your flash with the full benefits of a flash designed for your camera using E-TTL . I have no idea what the Vivitar's guide number is but it would have to have a fair bit of power to be of any use with a brolly. There is also another issue if you are trying to activate another flash as a slave and that is the main flash sends out a pre-flash and this can activate the slave prematurely. Look up the site The Strobist a lot of good information can be had there and if it can be done with flash someone there has done it. I have the 420 ex and the 580 Ex II but from what I have heard the 430 Ex is an excellent flash and at $240 well worth it.

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