[HELP]Flashgun firing but photo's not exposing.

jxmt018897

jxmt018897

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Hi Guys!
I've recently bought a second-hand Sigma EF 500 DG ST for my Canon 450D.(first time having a flash on my camera)
After testing I found the TTL sync is working,flash fires, but the picture is not exposing the light...
Here's a video on youtube showing the problem...
[YOUTUBE]cvMDYaHWdYM[/YOUTUBE]
Could someone have a look and give me some help please :p
Thank you!!

(y)(y)
 
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It's just the last section after the = in the URL that you need to use in the youtube links. Post a full link if you're struggling :)
 
Nope, its like that for all modes.. It occasionally works but most of the time its just not exposing at all...
 
It sounds to me as though there's a fault in the flash outputting a consistent quantity (for want of a better word) of light. Where did you buy it 2nd hand from?
 
I tried using long exposures in a dark room to check if its the power of the flash but even after a long exposure the picture is still not exposing any of the light.. It feels to me as if the flash is going off before the mirror actually moves up to expose the sensor..

the flash came from ebay.
 
This might sound like a newbie response but in the video you can see the flash fire long before you hear the shutter ?
 
Carlos68 said:
This might sound like a newbie response but in the video you can see the flash fire long before you hear the shutter ?
Click to expand...

The audio of the video is slightly out of sync with the visual. They do fire at the same time as far as my eyes can tell....
:shrug::shrug:
 
I know nothing about canon or that type of flash but is it possible one or the other has the flash acting as commander sending out pre flash only to fire other guns which aren’t there
 
It looks like the E-TTL pre-flash is firing, but for some reason the main flash isn't. Does it work with the gun in full manual? There is no pre-flash in this mode.

I don't think that Sigma gun can act as a master/commander, so therefore you cannot disable the main flash.
 
HoppyUK said:
It looks like the E-TTL pre-flash is firing, but for some reason the main flash isn't. Does it work with the gun in full manual? There is no pre-flash in this mode.

I don't think that Sigma gun can act as a master/commander, so therefore you cannot disable the main flash.
Click to expand...

The flashgun does not fire at all on MH or ML (the 2 manual modes)...:thinking:

&& Yes its a Canon fit :p
 
Yup, it seems to work fine on my friend's 500D too... I think it might the spring on the mirror of the camera thats not flicking up fast enough? do such problems exist?
 
Have you tried it on second curtain setting
 
Folks often get confused with flash guns ;) but by a process of elimination, ie your flash on another camera and another flash on yours, will isolate the problem.

With E-TTL flash, when you press the shutter release, a pre-flash is fired which is then measured by the camera's metering system for exposure. Then the mirror rises and the shutter opens, and the main flash is fired at the metered power output. The two flashes go out in such quick succession that they look like one with the naked eye.

In manual, because there is no exposure metering to be done, the pre-flash doesn't fire and only the main flash is emitted.
 
HoppyUK said:
Folks often get confused with flash guns ;) but by a process of elimination, ie your flash on another camera and another flash on yours, will isolate the problem.

With E-TTL flash, when you press the shutter release, a pre-flash is fired which is then measured by the camera's metering system for exposure. Then the mirror rises and the shutter opens, and the main flash is fired at the metered power output. The two flashes go out in such quick succession that they look like one with the naked eye.

In manual, because there is no exposure metering to be done, the pre-flash doesn't fire and only the main flash is emitted.
Click to expand...


Now that explains alot! thank you!(y)
So If ive understood correctly,when tested on ETTL, a flash fires, that would be the preflash... the reason my pictures are dark is because the main flash isnt firing...
By testing it on manual nothing is fired beccause the preflash isnt needed in this case and the main flash isnt firing like in ETTL.. Correct?

Would that be caused by the communication through the hotshoe then?
 
jxmt018897 said:
Now that explains alot! thank you!(y)
So If ive understood correctly,when tested on ETTL, a flash fires, that would be the preflash... the reason my pictures are dark is because the main flash isnt firing...
By testing it on manual nothing is fired beccause the preflash isnt needed in this case and the main flash isnt firing like in ETTL.. Correct?

Would that be caused by the communication through the hotshoe then?
Click to expand...

Yes. And the test button fires the main flash, so that should establish that the gun is actually capable of putting it out. So if that works, and the gun works properly on another camera, then there's some communication breakdown in the hot-shoe contacts or related internal connections.

It could be just a dodgy contact. Clean them, fit carefully, lock it down correctly - there should be a pin that engages.
 
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HoppyUK said:
Yes. And the test button fires the main flash, so that should establish that the gun is actually capable of putting it out. So if that works, and the gun works properly on another camera, then there's some communication breakdown in the hot-shoe contacts or related internal connections.

It could be just a dodgy contact. Clean them, fit carefully, lock it down correctly - there should be a pin that engages.
Click to expand...


Ahh I see! Thank you very much for your help!! :) (y)(y)(y)
 
HoppyUK said:
It looks like the E-TTL pre-flash is firing, but for some reason the main flash isn't. Does it work with the gun in full manual? There is no pre-flash in this mode.

I don't think that Sigma gun can act as a master/commander, so therefore you cannot disable the main flash.
Click to expand...

Can the camera be set to 'Emit but not fire' with respect to an external flash?
 
Theres a lot of things it could be, first off try it on a second camera set to program and see what happens, if it's not working on that chances are the flash has some fault.
I'm assuming you have the fllash and camera set up properly with no flash compensation set and the camera set to first curtain sync etc and that the flash is not set to commander mode or something.
 
Asking the obvious???

1) Have you tried your friends flash on your 450D? You said he had tried yours on his 500D and it works!

2) In the video you say using 1/125s are you sure that you have not set a Tv of greater than 1/180 the max apparently for this flashgun? Have you got the image files that you said you took first of all if so what is the EXIF???

3) Does the onboard flash work AOK?
 
Hey everyone thank you for your help!
I tried the flash on my friend's 500D again and another 1000D and non of it works anymore.
I've noticed there's a large bit of the silver coating missing on the front pin of the flash.
The Exif says Flash was fired but the flash activity is Unknown(133) whatever that means....
I have contacted the seller on Ebay and probably gonna return the item for a refund and try my luck with another flash.

Aprreciated the help guys!
 
I agree with the comments made about the flash firing before the camera exposes and the sound doesn't seem too far out of synch. I would say that what you are seeing is pre-flash.

On the 7D if you have flash disabled in the menus the flash can still fire as focus assist or redeye reduction, but will not flash when the picture is taken. I wonder if you have something similar set on your camera.

Top way of presenting the problem by the way. (y)
 
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