1D4 exposure issues

Flats

Flats

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Name
Jonathan
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Hi
Very occasionally, but more than once, this body has a complete exposure fit and drastically underexposes the subject to the point of almost producing a black image. Switch off and on again, and it's back to normal. I am worried that one day it will cost me a shot.
Anyone heard of this happening before?
Rgds
Jonathan
 
I know this probably doesn't help, but on every occasion this sort of thing has happened to me it has been user error.
 
I am in AV mode 100% of the time, using eval metering, and more often than not, the centre point only, with any lens wide open.
No exifs as I delete them all immediately, but usually what happens is that my shutter speed jumps up to 6400 or above, whereas it should be 320, 500, 640 etc to get a properly exposed image. Usually I spot this in time, and realise that it's wrong, but in the heat of the moment I do get caught out for a couple of shots.
I'd day it happens in dull light rather than sunshine, and with no flash. I'd normally agree with the user error comment, but not in this instace. You see it happen, you switch off, then on, you recompose the exact same scene, no settings changed, and you're in business again.
Thanks
 
Greywolf said:
I know this probably doesn't help, but on every occasion this sort of thing has happened to me it has been user error.
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How so? I'd normally agree but in this particular situation I don't. I'd expect the camera to meter properly, and very occasionally, though more occasionally than makes my happy. What do you think that I might be doing that would cause the camera to grossly underexpose an image to the point of almost complete darkness?
 
you aren't on auto iso by any chance, Jonathan?
 
Flats said:
How so? I'd normally agree but in this particular situation I don't. I'd expect the camera to meter properly, and very occasionally, though more occasionally than makes my happy. What do you think that I might be doing that would cause the camera to grossly underexpose an image to the point of almost complete darkness?
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a very bright scene would be more than enough. there is exposure compensation for a good reason
 
Jonathan,

It would well worthwhile saving the RAW file next time it happens. The clue could well be buried deep in the hex words but I believe it'll show the reason. The other possibility is that the exposure is actually correct but the processing of the embedded JPG (the image shown on the review screen) is wrong....something that was seen on 1DII's IIRC
If you can grab a supposedly under-exposed RAW, I'd be interested to dig into the data.

Bob
 
Your in AV mode so the camera is setting the exposure not you
Your using center spot only to get the metering..

Isnt it simple that your center spot has landed on something bright?
 
I am in AV, using Eval metering, not spot, not anything else. Tonality of scenes has been normal; suggestions of me being a numpty are well wide of the mark. You expect someone with a 1D4 not to know about exposure compensation, or how metering works? Pfffff....

Seriously, this is a camera problem, I am trying to establish why.

I do shoot RAW, so I'll try and keep the file next time.
 
I'd get it checked. Sounds like a problem that won't fix itself and will cost you shots sooner or later. Is the camera still in warranty? Even if not, I wouldn't be surprised if Canon waived any charge as you must be close. Are you a CPS member?
 
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HoppyUK said:
I'd get it checked. Sounds like a problem that won't fix itself and will cost you shots sooner or later. Is the camera still in warranty? Even if not, I wouldn't be surprised if Canon waived any charge as you must be close. Are you a CPS member?
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Have to agree, I've had no similar issues with my MK4 ,and as they all came with a 2 year warranty, you'd have bought the first of the boat for in not to still be under warranty.
 
Flats said:
I am in AV, using Eval metering, not spot, not anything else. Tonality of scenes has been normal; suggestions of me being a numpty are well wide of the mark. You expect someone with a 1D4 not to know about exposure compensation, or how metering works? Pfffff....
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Well there are plenty of numpties with good cameras beleive me! I'm sure you arent one of them but the fact does remain that most of the time this sort fo thing is user error. If it IS a camera issue then defintiely send it in.

I had this problem on my 5D a couple of years ago sporadically. I eventually realised that it was direct sunlight coming in through the viewfinder and fooling the light meter. Sounds like that isnt the case for you but thats just one example of how us numpties can get it wrong :)
 
Hi, it did it again this morning whilst taking photographs of Teal. I remembered to save the RAW. I stopped metering for a second, then re-depressed the shutter button. The exposure was the same, 1/1000 at f5.6. I turned the camera off and on again, without even moving, and lo and behold the new exposure was 1/250 at f5.6.
I had a 1.4x converter on, with a 300 f4 lens, using ISO 800, -1 1/3.
RAW files are too large to post on here. How can I show people the files, or at least the info within the files?
Regards
Jonathan
 
Addtional info - My two RAW files are 10 seconds apart, both using the centre point only, and are both focussed exactly on the 2/3 the head of the bird, 1/3 the neck, which in a Teal is dark head, and a silvery neck.
 
Does it do it when you are using it without a teleconverter?

Does it do it if you use centre weighted metering under the same conditions?

If answer to either of those is yes then I'd get it off to canon to investigate.
 
srichards said:
Does it do it when you are using it without a teleconverter?

Does it do it if you use centre weighted metering under the same conditions?

If answer to either of those is yes then I'd get it off to canon to investigate.
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Today was with the tc, previous times I cannot remember. I have the converter on less and less at this time of year, but it's not possible to say unless I see it happen again without the tc.

I only ever use Eval, literally 100%. Next time I will try and remember to flip it to Centre and see what happens. But that test is not necessarily valid as changing a setting could cause it to "snap out of it" so to speak. Ie, rotating ap by 1/3 of a stop could also cause it to right itself. But an interesting theory and one I should take a look at. More often that not though I'm more concerned with the shot than fiddling about. Today I knew the shot would be poor anyway, so I should have done some more fiddling.
 
I used to use evaluative metering but found that it was randomly bonkers and would over expose or under expose for no reason. I switched to centre and that is much more predictable.

I had a massive under exposure at a car show when the sun reflected off a bonnet. I realised it was partly a dynamic range issue as the camera thought it was all much brighter than it actually was. I moved a few feet to one side and it was fine. Doesn't sound like you have the same thing if you're framing the shot in exactly the same way and it is metering differently between shots.
 
srichards said:
I used to use evaluative metering but found that it was randomly bonkers and would over expose or under expose for no reason. I switched to centre and that is much more predictable.

I had a massive under exposure at a car show when the sun reflected off a bonnet. I realised it was partly a dynamic range issue as the camera thought it was all much brighter than it actually was. I moved a few feet to one side and it was fine. Doesn't sound like you have the same thing if you're framing the shot in exactly the same way and it is metering differently between shots.
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I find matrix metering very good, and the only time i use spot is when the subject is backlite or has alot of dark behind it.

also what mode are you in jonathan.
 
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I've just had a look at the two RAW files from Jonathan and can see a difference in execution. I've emailed a question back to make sure we don't put an erroneous info in this thread.

Bob
 
Just coming back to this in case people were curious. Bottom line, the camera is fine. Bob was able to look deep into the raw and discover that the underexposed shot had had the * pressed to lock the exposure. About 50 seconds had elapsed between my last good shot and the bad one. My guess is that while reviewing the image or moving the camera, the way I hold the body could mean that the side of palm/thumb on my right hand could inadvertently push the * button on the grip, and if the camera, angled perhaps 45 degres down towards some bright water if reviewing an image, or up to the sky if pausing between shots as I sometimes do - though in this instance exposure was not extreme so likely a brighter patch of water.

I think I confirmed Bob's theory just this weekend when photographing a gull all of a sudden I had 1/8000 suggested. I made sure to check the viewfinder and sure enough, the dreaded * lit up. So it's all my fault. I never use AE lock, but I think it's possible - maybe - in the CFs to reassign the button so I may do that. One thought was to switch off the grip buttons but I flip the camera too frequently to want to do that.

Thanks all

Jonathan
 
Good work from Canon 'Sherlock' Bob :thumbs:
 
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