topic Re: 6D Random underexposed image in EOS DSLR & Mirrorless Cameras

6D Random underexposed image

Z0mbieRecruiter — Fri, 04 Aug 2017 12:57:31 GMT

Hello. I hope you can help. I own a Canon 6D and twice in the past week I was taking photos where a random image would come up underexposed. I was shooting in manual mode, each image was identical other than a slightly different angle and shot only a few seconds from each other. Looking back at the settings for each image, the settings are exactly the same (ISO 1600 F/5.6 1/60 sec). While taking the photo, the image in my view finder also darkened. Both times this happened using the same lens, so I suppose it is possibly a lens issue?

Thanks in advance!

Re: 6D Random underexposed image

kvbarkley — Fri, 04 Aug 2017 14:47:26 GMT

If there is no difference in the EXIF data between good/bad shots (i.e., the ISO suddenly goes from 800 to 100), then it sounds like an aperture problem with the lens, especially if the viewfinder goes dark.

Re: 6D Random underexposed image

Z0mbieRecruiter — Fri, 04 Aug 2017 15:12:55 GMT

Thanks. This does make sense to me. What could cause this issue? Could the lens just need a good cleaning? I was using a Sigma 2.8 28-70MM lens.

Re: 6D Random underexposed image

kvbarkley — Fri, 04 Aug 2017 15:18:32 GMT

I don't know. It seems weird that it would stick at a *smaller* aperture. I could understand overexposing by the aperture not switching from wide-open-focus-exposure-mode to picture-taking-mode, but going *past* the set aperture to a smaller one is unexpected.

You might see if Sigma has a firmware update.

Re: 6D Random underexposed image

BurnUnit — Fri, 04 Aug 2017 15:23:55 GMT

Depending on your grip on the camera, is it possible that you might touching the DOF preview button on the camera body? I tend to forget that I even have that feature on my 60D.

Maybe cleaning the electrical contacts betwen the lens and body would help. Do you only have the problem with the one lens you mentioned? You're not using a flash for the shots in question, are you?

Re: 6D Random underexposed image

diverhank — Fri, 04 Aug 2017 15:28:15 GMT

@Z0mbieRecruiter wrote:
Thanks. This does make sense to me. What could cause this issue? Could the lens just need a good cleaning? I was using a Sigma 2.8 28-70MM lens.

I don't think cleaning will help. It's probably some incompatibility between the 6D and this Sigma lens. I'd do the following:

1. update the firmware for the lens

2. update the firmware for the camera (if not done already)

3. Turn off the camera's corrections like vignetting or peripheral illumination correction, etc.

Re: 6D Random underexposed image

Z0mbieRecruiter — Fri, 04 Aug 2017 15:43:21 GMT

No, no flash being used. I could look into the contacts. I've been using this lens for the past 2-3 years and the camera for 1.5 years without problems until this past week. Thanks for the suggestions

Re: 6D Random underexposed image

Z0mbieRecruiter — Fri, 04 Aug 2017 15:44:06 GMT

I have not updated the firmware for some time, so I will look into this as solution. Thank you for your help!

Re: 6D Random underexposed image

MichiganPhoto — Tue, 12 Dec 2023 17:58:12 GMT

I have this exact same issue. Except, I'm using the "kit" Canon 24-105 F4L mostly but, it also occurs on my other lenses... A new Tamron 35mm 1.4, Canon 70-200 F4L, Tokina 11-16, Canon 50mm 1.8 STM..... If it was a lens problem this would also occur on my Canon 6D Mark II, SL1, M50, and M100 (which it does not). So, it is a camera problem 100%. I will reiterate - all of these lenses work perfectly on my other Canon rigs.

I figure something must be wrong with the shutter mechanism, causing it to occasionally go much faster for some reason (which is odd, as they would typically stick). I can often pull the shadows on these images and see what I was taking but, they're too underexposed to be "usable" for any client or publication. I would love to know if there is any new information or others who have had this problem fixed? The camera is old but, otherwise works flawlessly and I'd much prefer to keep it going over shelving it for something that might easily & affordably be repaired.

I have cleaned the contacts recently, but have attempted no other service.

I also wanted to counter the "accepted solution" in this post which is patently incorrect for others who may stumble across this, as it is clearly not a lens issue.

Thanks!

Re: 6D Random underexposed image

Peter — Tue, 12 Dec 2023 19:33:59 GMT

Different shutter speeds? Then the light meter in the viewfinder may be off. Easy to test. Just use Live view.

Bright and dark images even with the same exposure? Then check the aperture. Largest aperture and take a look from the front of the lens. Is the aperture moving when it shouldn't?

Re: 6D Random underexposed image

MichiganPhoto — Tue, 12 Dec 2023 20:32:38 GMT

As stated in OP. Precisely same settings on both successive images. Very random in nature. I've only noted it in the VF and not in LV.

Can occur with multiple lenses. So, it's not aperture, unless the camera is stopping it down for some reason. If the camera is stopping it down, it is not reflecting this in the EXIF. By all metrics, identical settings and can happen w/in seconds of each other so, it's not a drastic change in ambient light.

This problem occurs irrespective of whether or not the aperture is stopped down or wide open. But, I typically shoot wide open unless I have a need for stopping down.

I do not recall it happening in live view. But, the live view experience in the old 6D is abysmal so LV doesn't get used unless on a long exposure with a tripod. To whit... I have not noticed this occur on such occasions.

I'm really hoping to find someone who has actually solved this issue, but I thank you for your time.

Re: 6D Random underexposed image

Peter — Tue, 12 Dec 2023 21:05:57 GMT

As I wrote, take a look at the front to see if the aperture moves when it shouldn't. I don't really know what else could be the culprit...a slow shutter curtain, but that should give other symptoms also.

Firmware 1.1.8 solved irregular exposure, but only in Live view and with some TS-E lenses.

Any raw samples with the same settings and different brightness?

Re: 6D Random underexposed image

Z0mbieRecruiter — Tue, 12 Dec 2023 21:30:54 GMT

Just adding updates as the original poster. After trying updates, I broke down and got the lens repaired /cleaned. The tech didn't see anything as an issue, put it back together and problem stayed. Took it apart and cleaned again, worked w Sigma and it just started working again. I still use as my main lens and have only had the problem happen one more time a few months ago after 5 years of use.