Shutter misfire with external flash- 40d.

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Bigdeaks

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On occaisions when using an external flash with my 40d, particularly when using 6fps, i will get a shutter misfire. By this i mean the shutter fires as normal but sounds like a much faster click then those on either side and i get a black frame. It is not just that the flash does not fire- its like the shutter misfires.

Its not a problem in itself, and i first noticed it when using a Cactus v4 radio trigger with external strobes. I put it down to the trigger, but I have recently got a 430ex II and the same thing happens. Maybe 2 or 3 frames every hundred or so.

Is this normal? Or is the shutter dying? If it makes any difference my 40d is about 8 months old running latest firmware with about 15,000 clicks. Never had any err codes or anything like that.

Any ideas?

Ollie
 
If it's the shutter, it will do it with or without flash. Try that.
 
I have tried but cant replicate it without a flash/trigger mounted.

Im pretty sure its not just the recycling time of the flash. If that were the case then why would it happen with the radio trigger where there is no communication back from the trigger to the camera- just a fire trigger from the camera to the trigger. To clarify it seems to happen randomly, not just 5 or 6 frames into a burst, and the shutter sounds like it is firing really fast.

I have had a look at one of the 'black frames' in more detail, I will try and post an example to show what i mean.
 


This is one of the 'black frames' run through lightroom with the exposure and brightness maxed out.

Exif shows
Exposure 0.017 sec (1/60)
Aperture f/5.0
Focal Length 50 mm
ISO Speed 100

The banding looks like the shutter speed is obvioulsy faster then 1/60 sec and it sounds quicker too. Strange also that on this photo the flash had HSS on which should have meant that it synchs whatever the shutter speed, although it has happened with HSS on and off.
 
Bigdeaks said:
Im pretty sure its not just the recycling time of the flash. If that were the case then why would it happen with the radio trigger where there is no communication back from the trigger to the camera- just a fire trigger from the camera to the trigger.
Click to expand...

The recycle time has nothing to do with whether the flashgun is mounted on wireless triggers or not, it's to do with the power setting you have the flash at and the type of batteries you are using.

The 430EXII has a recycle time of 3.7 seconds at full power - this means that every time you fire a full power shot the flashgun needs 3.7 seconds before it can do it again.

If you're firing off the flash six times per second, even at much lower power settings, you're going to get to a point where the flash isn't recharged in time to illuminate the shot, so you get a black frame.

Flashguns also use a lot of battery power, so you need good quality, high-mAh rated rechargeables to get the best results.Even then the flash will run through them pretty quickly. As the power in the batteries wains they will take longer to recharge the flash, again leading to more misfires.....
 
Bigdeaks said:


This is one of the 'black frames' run through lightroom with the exposure and brightness maxed out.

Exif shows
Exposure 0.017 sec (1/60)
Aperture f/5.0
Focal Length 50 mm
ISO Speed 100

The banding looks like the shutter speed is obvioulsy faster then 1/60 sec and it sounds quicker too. Strange also that on this photo the flash had HSS on which should have meant that it synchs whatever the shutter speed, although it has happened with HSS on and off.
Click to expand...


Are you trying to use HSS with a set of triggers?
 
Thanks for your thoughts.

It has happened with sb-26's fired by cactus v4 radio triggers and with the 430 on camera. I have only tried HSS with the 430 and it has happened with and without it on. I havent tried the 430 wth the radio trigger.

I understand about recycling times and that the flash 'cant keep up' and I also get plenty of shots where it doesnt fire and the photo comes out dark with no flash illumination, but I do think this is different. Its as if for whatever reason the shutter decides to fire at 1/4000sec. The photo is what i would expect to look like at a really high shutter speed and the shutter sounds like it as well.
 
Inconclusive. You need to isolate the possible causes.

If it's the shutter, maybe firing off a random frame at a much faster speed than set, it will do it with or without flash.

If the flash isn't recycling in time, then it won't flash. It looks like strip at the top is the flash.

Then there is the trigger. The notorious Cactus. If I was to guess, I would say that's the problem. What might be happening is that the batteries are tired, and they get even more tired during a burst. So the firing signal goes out very late and you're only catching the last moment of the exposure. The dark band from the bottom up is the second shutter blind closing.

I think the HSS thing is a red herring. The flash will revert to normal operation on a remote trigger, and even on the camera it only engages when the shutter speed goes over 1/250sec, then switches off when the shutter speed drops below that.

Guess: the trigger. And you've been hearing things.

The only thing that makes me think the shutter might be misbehaving is your comment about the different noise it makes. That might suggest a random misfire at high speed which would cause the banding.
 
As Richard says, if it was the shutter then you'd be able to replicate that shot without a flashgun or triggers.
 
HoppyUK said:
Then there is the trigger. The notorious Cactus. If I was to guess, I would say that's the problem. What might be happening is that the batteries are tired, and they get even more tired during a burst. So the firing signal goes out very late and you're only catching the last moment of the exposure. The dark band from the bottom up is the second shutter blind closing.
Click to expand...

Its not the cactus trigger as it happens with the 430ex mounted on the camera in ETTL mode (such as in the example i posted). For what it is worth I have been very pleased with the cactus triggers and have found them to be very reliable.

Personally I think it is the shutter misbehaving. Just strange that it hasnt occured without the flash... looks like im going out with the dogs to fire off a few hundred shots to see if i can make it will happen without flash....

If it is the shutter dying, i just hope it goes before the waranty is up!

Thanks again for your thoughts.
 
No need for dogs - just rattle off a load of frames at the wall!

Make sure you give it a good pasting at 1/60sec as that is the proven problem speed. It might not be a shutter problem directly but a switching/timing problem only at that setting.
 
Nope... happily fired off a couple of hundred frames without flash starting off on the same settings as the frame I uploaded and then at a variety of apertures and shutter speeds. No misfires. Incidently I have looked at a couple of the other 'black frames' and they are at a varity of shutter speeds/apertures, the only constant seems to be that there is something on the hotshoe. Unfortunately I have deleted most of them as they are pretty infrequent and I obviously didnt think too much of it at the time.

I have emailed canon support to see if they can shed any light (so to speak)
 
Well went out with the dogs and did manage to get a single misfire without the flash. Was actually the first shot I took of about 400 shots.

So that rules out the flash unit/setting being the problem... even if it seems to make it happen more often, which leaves the obvious question- what is at fault? shutter mechanism? shutter button? the electronics?
 
It looks like the shutter blinds are not opening properly, but travelling down together and only separating at the very last moment.

Repair job :(
 
Minimal and arty, I like it :lol:

i would get it back to Canon and include misfire pics on an email, shoot again tomorrow and see if it does it again. Least if you log it as a repair with Canon then if it goes just after warranty you will have a stronger case to get them to fix it.

Only other thing I can think of is do you format your card in camera before use every time, and has this occured on separate cards?
 
Well I sent it off to Canon RCC with some example pics, and recieved it back within a week with a full clean and a new shutter assembly (with a further 6 month warranty on the shutter). Have to say Im very impressed with the service, but still dont understand why it was more prevalent with the flash attached- but hopefully a thing of the past now.
 
Good news :thumbs:

Thanks for the update :)
 
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