Flash gun firing but black pictures!

rbrown74

rbrown74

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Rick
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Hi guys,

I got myself one of the major bargain Jessops 360AFC flashguns for my canon450D.

It worked the first few pics I took so I put it away and only got it out again today. It wouldnt expose the pics. I coudl see it firing but the pics were black or pratically black screened. Futtered about for a while trying all sorts of settings, taking it off and on and then got about 6 good pics. Set it down, picked it up 10 minutes later turned all on and back to black again - havent had a pic from it since. Tried all modes and no joy. Turkey??
 
It sounds like your shutter speed is too high, try dropping it down below 1/250 :)
 
Check you shutter is not set higher than the maximum sync of the camera - possibly 1/200 on that body but not sure

Too slow typing !
 
Possibly too high a shutter speed - or a shutter speed that should theoretically work, but which in fact will only work under perfect conditions - but which won't work if the flashgun batteries are past their best.
 
Vasectomy Club sale? Actually, I had the same issue with the Jessops 300D, it was all down to syncing with the shutter. Damned thing had too many options for me to figure out at this stage in my career!

Arthur
 
doesnt the camera auto sync at 200th or 250th when the flash gun is attached???
 
Dave450 said:
doesnt the camera auto sync at 200th or 250th when the flash gun is attached???
Click to expand...

I think it only does that in program or auto mode, usually Canons don't default the shutter speed in TV or AV although you can set it it the menus.
 
5D is 200th sec
40D is 250th sec, think the xxxD's are the same.

Have found with the 5D it's more like 160th and if you have a speedlite you can use a much faster shutter speed.
 
Gel said:
5D is 200th sec
40D is 250th sec, think the xxxD's are the same.

Have found with the 5D it's more like 160th and if you have a speedlite you can use a much faster shutter speed.
Click to expand...

450D is 1/200
 
Have you got the Jessops gun off-camera and in manual mode?

If so, it's probable that it is slaving off the pre-flash so that it appears to be working normally but in fact the flash has been and gone before the shutter actually opens.
 
Thanks for all the replies. I have the lens cap off thanks:) I'm aware of sync speeds for the camera being around the 1/200 mark but this thing is underexposing at speeds which aren't feasible for handheld photography in any mode using ttl.

Tried all modes and flashgun is showing the info from the camera - just isn't exposing pics at all, apart from 4 or 5 which mysteriously did work in the midst of it all. Tried fresh batteries too to no avail. :(
 
HoppyUK said:
Have you got the Jessops gun off-camera and in manual mode?

If so, it's probable that it is slaving off the pre-flash so that it appears to be working normally but in fact the flash has been and gone before the shutter actually opens.
Click to expand...

I had a this problem using flashes with a photo cell slave on them, try holding the * button in on the back of the camera to stop the preflash.
 
Flash In The Pan said:
Make sure you haven't accidentally flicked it onto slave function, it's easily done :whistling:
Click to expand...

Definitely in the right mode. Slave is off, auto zoom is working Ttl is on the screen of the flash and I can't get an exposed pic.

Had read that they can be tempramental in mounting on cam but I've taken it off and on a dozen times. Tried holding it down firmly in case of a dodgy contact. Like I say, it seems to display the right info but then goofs the pic. it does flash but I don't know what is up. :(
 
Bit long winded but is it worth resetting to defaults, then check/note down iso,ap and sht readings in all modes with and without flash attached, then comparing results. Meters can be fooled as can we.
 
rbrown74 said:
Definitely in the right mode. Slave is off, auto zoom is working Ttl is on the screen of the flash and I can't get an exposed pic.

Had read that they can be tempramental in mounting on cam but I've taken it off and on a dozen times. Tried holding it down firmly in case of a dodgy contact. Like I say, it seems to display the right info but then goofs the pic. it does flash but I don't know what is up. :(
Click to expand...


Does it work in slave mode, triggering off the camera's onboard flash?
 
Flash In The Pan said:
Does it work in slave mode, triggering off the camera's onboard flash?
Click to expand...

I think that may be the problem, as I posted above. If a remote gun is set on manual, it will fire off the pre-flash.

You cannot disable the pre-flash on a Canon. The only work-around way of doing it is to press the FEL * button which fires it separately, which will then trigger the remote gun, wait for it to recycle and then take the picture when the remote gun will fire again off the on-board's main flash.

That will work. It will also confirm if that's the problem.

Can't be sure as the OP has not confirmed exactly what he's doing.
 
HoppyUK said:
I think that may be the problem, as I posted above. If a remote gun is set on manual, it will fire off the pre-flash.

You cannot disable the pre-flash on a Canon. The only work-around way of doing it is to press the FEL * button which fires it separately, which will then trigger the remote gun, wait for it to recycle and then take the picture when the remote gun will fire again off the on-board's main flash.

That will work. It will also confirm if that's the problem.

Can't be sure as the OP has not confirmed exactly what he's doing.
Click to expand...


There are optical triggers available that ignore the pre-flash, I'll maybe see if I can get some to try
 
If the flash is firing but is under exposing it is going off with the preflash, try holding the * button in on the back of the camera, if the flash flashes that is the problem. Like Hoppys says just wait for it to recycle then, and take the photo.
 
Just tried it using the optical slave. The flash triggers no problem but here is the strange thing. It's not affecting the pics even on longer exposures. I even took a pic of the flash pointing point blank at an object and it fired real bright but yet the pic didn't show any signs of flash, even slowed down to shutter speeds of almost 1/2 sec! onboard flash exposes fine. Really just wanted it for ttl on cam for quick snaps at events.
 
rbrown74 said:
Yep, think that'll be it. So manually it is fine. Just the ttl is screwed then.
Click to expand...

Rick, I think it's just the reverse. It will work as intended in E-TTL which can only work with the pre-flash.

It's manual operation that is the problem, and the best way around that is to use a radio trigger which completely circumnavigates the pre-flash, as I think you have found.
 
HoppyUK said:
Rick, I think it's just the reverse. It will work as intended in E-TTL which can only work with the pre-flash.

It's manual operation that is the problem, and the best way around that is to use a radio trigger which completely circumnavigates the pre-flash, as I think you have found.
Click to expand...

So are you saying that it will not work in ttl because of the pre flash? Surely it knows to ignore this?!? I'm getting confused. :'(
 
HoppyUK said:
Rick, I think it's just the reverse. It will work as intended in E-TTL which can only work with the pre-flash.

It's manual operation that is the problem, and the best way around that is to use a radio trigger which completely circumnavigates the pre-flash, as I think you have found.
Click to expand...

rbrown74 said:
So are you saying that it will not work in ttl because of the pre flash? Surely it knows to ignore this?!? I'm getting confused. :'(
Click to expand...

:eek:
 
rbrown74 said:
Sorry,hadn't read it correctly. Apologies.

Preflash is on given the way it was firing optically. Surely then ttl should work. Still confused
Click to expand...

Yes.

The only way you can fire the remote gun, and sync it properly, is in E-TTL mode. In this way, the camera will attempt to set correct exposure and balance the light from both the on-board flash and the remote gun together. It's well clever.

According to the camera's exposure mode (eg Av) it will also try and balance the ambient light exposure with the flash, by adjusting the shutter speed. Even cleverer :thumbs:

If you want to work in manual, you need to switch off the on-board flash and use a separate trigger, which fires off the central hot-shoe pin and so is not affected by any of the pre-flash pulses that are causing you problems.

All current auto flash systems work by firing a pre-flash the moment you press the shutter release (there is actually a stream of high speed pulses for both calculating exposure, and instructing the remote gun via a series of morse-code like signals). After all this, then the shutter opens and the main flash is fired for the actual exposure. The pre-flash and main flash are fired incredibly quickly - so fast that you cannot distinguish the two by eye.

Because you cannot turn off the pre-flash, when you have the remote gun in manual it doesn't know to ignore the pre-flash and so fires immediately on that - it's all over and done with way before the shutter even opens for the actual exposure.

HTH :)
 
Thanks for thereply. But I think we're getting crossed wires here.

I tested the flash manually with triggers and optically just to make sure the flash worked ok. I'm not trying to fire an onboard with a remote flash. Just the jessops onboard using the ttl and getting pics similar to not using a flash at all .

Thanks for the replies to date, just not getting something right here.
 
rbrown74 said:
Thanks for thereply. But I think we're getting crossed wires here.

I tested the flash manually with triggers and optically just to make sure the flash worked ok. I'm not trying to fire an onboard with a remote flash. Just the jessops onboard using the ttl and getting pics similar to not using a flash at all .

Thanks for the replies to date, just not getting something right here.
Click to expand...

Okay, let's start again....

Is the problem that when the flash is mounted on the camera hotshoe and set to ttl mode that it is not working?
 
Okay, then assuming you have tried everything suggested here. it can only be that the Jessops gun is firing a pre-flash and appearing to work, but not following up with the main flash, ie faulty.

Take it back and try another one.
 
HoppyUK said:
Okay, then assuming you have tried everything suggested here. it can only be that the Jessops gun is firing a pre-flash and appearing to work, but not following up with the main flash, ie faulty.

Take it back and try another one.
Click to expand...
Sounds like the most probable answer tbh

Flash In The Pan said:
Okay, next step, could you post an example, so that we can have a look at the EXIF data
Click to expand...
I'll give it a go once I'm back inside. On my mobile at the mo
 
Flash In The Pan said:
Okay, next step, could you post an example, so that we can have a look at the EXIF data
Click to expand...

Right took 3 pics and uploaded to flickr as follows:
First pic - no flash at all
4282153590_fbffd26f7a.jpg


Second pic - on board flash
4282153596_aa59738c78.jpg


Third pic - Jessops flash mounted on board - full ttl readings coming up on the screen of the flash, flash seemed to fire but.....
4282153606_32402a621f.jpg


forth pic, taken yesterday and the flash actually worked 4 times in a row!!
4282153618_03fefd7403.jpg

See all here:
http://www.flickr.com/photos/38708674@N08/?saved=1

(hope that all works!)

Thanks again guys for taking time to help.
 
According to the EXIF data the flash fired on the third shot, the only real difference I can see between that and the 4th one is the iso :shrug:
 
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