Auto-ISO fail in 7DII

Edit. NOTICE: This was user error, pure and simple. No problem with auto-ISO or metering.

I have experienced this several times, including twice this morning. I am photographing birds with my 7DII and Tamron 150-600. I have my camera on Manual, f/8, 1/1000 sec, and auto-ISO. Occasionally the camera will select an ISO that either over- or underexposes the shot by 2.5 to 5 stops. When I notice that this has happened I can take additional shots and determine what the proper ISO would have been, so I know that the error is not always the same. Today I was taking shots that should have been at ISO 250 or 320, and the camera set ISO 5000. Later, I was taking shots that should have been ISO 1600, and the camera set ISO 250.

Also, the shots that are improperly exposed are not all taken with the same metering. That is, I use BBF, and meter with the shutter button. A series of bad shots might have a separate metering for each shot. Usually the bad exposures stop after 10-12 shots, and things are fine for a while. However, this is troubling, and I don't want it to happen when I am trying to get a shot of an Ivory-billed Woodpecker or something.

I had not heard about this problem, and was wondering if anyone else had. I would also be interested in hearing any theories and possible remedies that might be out there.

Thanks.

I haven't noticed this with the same setup. Are you using Evaluative, Center weighted, Spot, or Averaging for the metering mode? About 1/2 of the time I use Center weighted, if a dark enough bird fills the center of the view ( like a Crow or Great-Tailed Grackle) the exposure will change by a couple of f-stops.

-russ

Do you get exposure problems in AV / TV

I'd also try different metering modes. A smaller dark bird on sparkling in the sun water will throw the camera off more in some modes than other, as will a white bird on dark background. I've had the same happen with my 5D3 at times and figured that's my problem. Look at the bad photos and check what metering was used and if the brightness between subject and background is very different.

russbecker wrote in post #17599075
I haven't noticed this with the same setup. Are you using Evaluative, Center weighted, Spot, or Averaging for the metering mode? About 1/2 of the time I use Center weighted, if a dark enough bird fills the center of the view ( like a Crow or Great-Tailed Grackle) the exposure will change by a couple of f-stops.

-russ

Thanks for the response.

I am using evaluative metering. I could understand if the subject was dark and it overexposed, or of the background was bright and it underexposed, but the instances today were the opposite of that. When it selected the lower ISO it was a dark subject (Meadowlark in shade), and when it selected an ISO 4+ stops too high, it was a bird against a bright overcast sky. While those latter shots called for some EC, the camera selected an ISO that resulted in an image that was totally blown out. I could not even tell what species the bird was from the images.

I used this sort of setup with a 7D for months before getting the 7DII, and never had this happen.

Thanks again. It appears to be something with the metering system, and perhaps changing the metering mode will make a difference, but If so, that still wouldn't explain why it would happen in evaluative.

john crossley wrote in post #17599131
Do you get exposure problems in AV / TV

I haven't been using AV or TV modes much since getting the 7DII. I guess it's worth a try, but I'm not sure why that would make a difference. I need to keep the shutter fast with this lens, so that would mean TV, and perhaps limiting the aperture range to make sure it stops down to at least f/8.

However, this should not be happening in any mode, and I do not really want to have to go back to AV or TV to avoid it. Perhaps trying a different priority mode would help gather data so Canon can fix things.

Thanks for your suggestion. I will give it a try.

phantelope wrote in post #17599154
I'd also try different metering modes. A smaller dark bird on sparkling in the sun water will throw the camera off more in some modes than other, as will a white bird on dark background. I've had the same happen with my 5D3 at times and figured that's my problem. Look at the bad photos and check what metering was used and if the brightness between subject and background is very different.

Thanks. However, as I was explaining while you were posting, the exposure errors are in the opposite direction of what would be expected if it was just the metering system being fooled by contrast between the subject and background. If it was working properly, the shots where the camera picked an ISO too high and grossly overexposed should have been underexposed. These were shots of a perched bird against a bright, white sky. A properly working metering system (using evaluative metering) should yield an underexposure of the subject in this situation, unless some EC is dialed in. Likewise, the shots where it selected an ISO too low and grossly underexposed should have been overexposed if the metering system was being fooled in the way you describe, and which we have all experienced.

This is odd behavior, and I suspect a defect in my camera. It may be a unique issue, since I cannot find any similar reports.

pknight wrote in post #17599182
I haven't been using AV or TV modes much since getting the 7DII. I guess it's worth a try, but I'm not sure why that would make a difference.

It would make a difference because you could confirm it is an issue with the metering system and not some other bug related to AUTO ISO or your lens. If there was a problem with the metering system it should swing the shutter or aperture the same way it swings ISO.

Yes, you have confirmed its an issue in M with your Tamron. Try it in other modes with your Tamron and in M with a Canon lens to determine if there is actually an issue with your body, lens or body/lens combo. You may even need to try TV and AV with a fixed ISO.

Just standard troubleshooting.

I had two shots that were greatly overexposed, among hundreds that were fine. As I recall, they were with my 100mm macro lens.These were not metering problems. I don't have an explanation other than a camera glitch. I haven't been able to replicate it. I just got back from a trip where I took scores of shots with two other lenses, with no bad shots. I typically shoot in Av mode with evaluative metering and a fixed ISO. I haven't had any head scratchers since the firmware update. But that is not proof of anything. And it wasn't one of the symptoms described as being fixed by the update. I remain vigilant to see if it happens again. I know this doesn't help the OP, but I thought it might provide a data point.

tonyxcom wrote in post #17599376
It would make a difference because you could confirm it is an issue with the metering system and not some other bug related to AUTO ISO or your lens. If there was a problem with the metering system it should swing the shutter or aperture the same way it swings ISO.

Yes, you have confirmed its an issue in M with your Tamron. Try it in other modes with your Tamron and in M with a Canon lens to determine if there is actually an issue with your body, lens or body/lens combo. You may even need to try TV and AV with a fixed ISO.

Just standard troubleshooting.

Makes sense, although my money would not be on a lens problem per se, as this lens worked without a hitch on an older body.

However, these errors are unpredictable and rare, so standard troubleshooting with multiple modes and lenses may be difficult. If it doesn't happen with lens B in TV mode over the course of a day's shooting, I really haven't proven anything, as it doesn't happen for weeks at a time with the 150-600, shooting hundreds of images a day. This is why I am hoping that anyone with similar experiences will see this and respond.

It might be worth checking the EXIF to see if AE Lock was selected. Similar problems have been reported before and it was discovered that the user was accidentally knocking the AE Lock button as he raised the combination to his eye and this had set the exposure based on the lens pointing downwards towards a dark surface.

Bob

maybe you can set up a test shot, a stuffed animal or just a book and bushes etc? Certainly an odd one, hope you can figure it out!

Canon Bob wrote in post #17599495
It might be worth checking the EXIF to see if AE Lock was selected. Similar problems have been reported before and it was discovered that the user was accidentally knocking the AE Lock button as he raised the combination to his eye and this had set the exposure based on the lens pointing downwards towards a dark surface.

Bob

There you go. That was it. I seldom use AE Lock, so it never entered my mind. Pretty simple, once you begin looking in the right place. Thanks!

If I am not going to use AE Lock often I need to move it somewhere else where I won't be hitting it by mistake.

Thanks again.

(Odd that this never happened with the 7D.)

pknight wrote in post #17599612
There you go. That was it. I seldom use AE Lock, so it never entered my mind. Pretty simple, once you begin looking in the right place..

It does flash up in the viewfinder

pknight wrote in post #17599612
There you go. That was it. I seldom use AE Lock, so it never entered my mind. Pretty simple, once you begin looking in the right place. Thanks!

If I am not going to use AE Lock often I need to move it somewhere else where I won't be hitting it by mistake.

Thanks again.

(Odd that this never happened with the 7D.)

Sometimes the buttons are a little more sensitive. I'll send you my Paypal address

john crossley wrote in post #17599666
It does flash up in the viewfinder

It certainly does, John, but action shots and BIF usually require concentration keeping the subject framed and not looking at specific viewfinder info (in general).

Bob