topic Re: Grossly over exposed images during rapid shooting Canon Mk III in EOS DSLR & Mirrorless Cameras

Grossly over exposed images during rapid shooting Canon Mk III

Bundu — Fri, 14 Jul 2017 16:38:44 GMT

Recently I had a problem with my new Canon 5D Mk III. My passion is photographing birds in flight and suddenly and ocasionally during rapid shooting the images are grossly over-exposed. I use manual exposure of 7.1 or 8.0, Auto ISO, High-speed continuos shooting, AI Servo AF mode and AF area selection.

The images below illustrate tha issue. All of a sudden the ISO shoots up from 800 in normally exposed images to 12800

in the over-exposed photos?

Has anyone experienced the same problem and if so how was it resolved/

Re: Grossly over exposed images during rapid shooting Canon Mk III

cicopo — Fri, 14 Jul 2017 16:49:02 GMT

I stopped using Auto ISO because it's not very consistent in picking a "Best ISO" for most situations. It seems to favor allowing a high SS over everything else.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Bundu — Fri, 14 Jul 2017 17:03:53 GMT

Thank you for your advice. Would you say the ISO jump is an inherent fault of the Camera, and how is it resoled?

Re: Grossly over exposed images during rapid shooting Canon Mk III

cicopo — Fri, 14 Jul 2017 18:38:13 GMT

I don't have that body but I'd say it's the fault of the software wrote to instruct the full line up of bodies with Auto ISO.

Re: Grossly over exposed images during rapid shooting Canon Mk III

TTMartin — Fri, 14 Jul 2017 18:54:37 GMT

@Bundu wrote:
Recently I had a problem with my new Canon 5D Mk III. My passion is photographing birds in flight and suddenly and ocasionally during rapid shooting the images are grossly over-exposed. I use manual exposure of 7.1 or 8.0, Auto ISO, High-speed continuos shooting, AI Servo AF mode and AF area selection.
The images below illustrate tha issue. All of a sudden the ISO shoots up from 800 in normally exposed images to 12800
in the over-exposed photos?
Has anyone experienced the same problem and if so how was it resolved.

I use Manual exposure mode with Auto ISO all the time on my 7D Mk II with no issues. 1/4000 is about twice as high a shutter speed than you need for birds in flight. I don't see that causing the issue so that was more of an observation.

The date stamp on the two photos are 5 minutes apart and the numbering indicates they are 10 frames apart. It might be more helpful to see the photo immediately preceding the overexposed one.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Bundu — Fri, 14 Jul 2017 21:00:41 GMT

Above is a sequence of for images all taken at the same burst on TV prioity, the details for the first and second above are depicted below. The same story for the 3rd and 4th as far as the iso jumping from 640 to 12800 then back to 640 for the last image.

In the previous example of flying birds I have normally exposed images following imediately after the overexposed images taken at the same time

I look forward to your comments.

Re: Grossly over exposed images during rapid shooting Canon Mk III

kvbarkley — Fri, 14 Jul 2017 21:45:08 GMT

You really need to try it in manual mode so that there is no autoexposure.

The only thing I can think of is that there is a loose flap of something that occasionally covers the exposure chip when the mirror is moving rapidly.

You might take the lens off, put the camera in cleaning mode and look inside to see if you see something.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Waddizzle — Fri, 14 Jul 2017 22:14:39 GMT

I had a similar issue with random over/under exposures. I never really figured it out, because it seemed to resolve itself when I started using back button focus. My best guess is that my thumb had nothing to do, so it may have hitting Exposure lock button.

Re: Grossly over exposed images during rapid shooting Canon Mk III

TTMartin — Fri, 14 Jul 2017 22:29:49 GMT

@kvbarkley wrote:
You really need to try it in manual mode so that there is no autoexposure.

The only thing I can think of is that there is a loose flap of something that occasionally covers the exposure chip when the mirror is moving rapidly.

You might take the lens off, put the camera in cleaning mode and look inside to see if you see something.

I agree it could be that the mirror is sticking up, which would keep light from reaching the metering sensor.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Bundu — Sat, 15 Jul 2017 07:17:51 GMT

Thank you for your comments and suggestions.

Yes I do use manual for flying birds, normally an F stop of 7.1 or 8, and Auto ISO - these are illustrated in the first images where the ISO set at 800 for the normally exposed and then suddenly jumped to 12800

In the next sequence I used TV -shutter priority @ 1000. the normally exposed image F7.1 and ISO 640, and the next photo adjusted the exposure to F6.3 and the ISO jumped to 12800.

So it happened in rapid shooting both in manual and shutter priority?

Re: Grossly over exposed images during rapid shooting Canon Mk III

Waddizzle — Sat, 15 Jul 2017 12:57:50 GMT

Use Evaluative Metering for hand held shots. I never find need to use anything else.

Re: Grossly over exposed images during rapid shooting Canon Mk III

TTMartin — Sat, 15 Jul 2017 13:09:10 GMT

I think the mirror mechanism not moving full back into position is the most likely cause of your overexposure.

I'd send the camera into Canon for service and cleaning.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Waddizzle — Sat, 15 Jul 2017 13:28:49 GMT

@TTMartin wrote:
I think the mirror mechanism not moving full back into position is the most likely cause of your overexposure.

I'd send the camera into Canon for service and cleaning.

Mechanical failure can never be completely ruled out, but I think this issue is more operator error than mechanical failure. I just don't see the mirror sometimes working perfectly, and then occasionally not working, and then coming back to life.

This seems to be more of a metering issue, than a mechanical issue. If the mirror were a problem, wouldn't it show up in the viewfinder?

Re: Grossly over exposed images during rapid shooting Canon Mk III

TTMartin — Sat, 15 Jul 2017 14:34:42 GMT

@Waddizzle wrote:

Not if it is just momentarily sticking. Or perhaps now that he knows to watch for it he may notice the viewfinder blanking longer than normal.

If he has 2nd shot focus set to shot priority, the camera will just shoot away without worrying about the mirror coming back to obtain focus (or proper metering). I keep mine set to focus priority so it will slow the shot rate down slightly as it ensures focus between shots (which requires the mirrors to fully return to position).

Re: Grossly over exposed images during rapid shooting Canon Mk III

RobertTheFat — Sat, 15 Jul 2017 14:46:24 GMT

@Waddizzle wrote:
@TTMartin wrote:
I think the mirror mechanism not moving full back into position is the most likely cause of your overexposure.

I'd send the camera into Canon for service and cleaning.
Mechanical failure can never be completely ruled out, but I think this issue is more operator error than mechanical failure. I just don't see the mirror sometimes working perfectly, and then occasionally not working, and then coming back to life.

This seems to be more of a metering issue, than a mechanical issue. If the mirror were a problem, wouldn't it show up in the viewfinder?

The other day, my wife, daughter, grandson, and I were riding in an excursion train, when a woman in our car offered to take a picture of the four of us. I handed her my 5D3, which was set to Av, 1/200, ISO 1250, with a forward pointing 600EX-RT in E-TTL mode. She ran off three quick shots (elapsed time of 2 seconds), and all three were grossly overexposed at f/3.2. I had taken a picture of my wife with the same settings two minutes earlier, and it was properly exposed at f/7.1.

The best hypothesis I could come up with was that maybe the woman had pressed the shutter button so fast that the camera hadn't had time to meter (and/or the flash hadn't had time to get its mind right), though the focus appeared OK. For the rest of the day and the next day, both with heavy use, the camera performed flawlessly, so the overexposures were definitely a fluke. Does my proposed explanation make any sense? And in any case, could what happened to me be causally similar to the events being pondered in this thread? (Note that I was not using auto-ISO.)

Re: Grossly over exposed images during rapid shooting Canon Mk III

Waddizzle — Sat, 15 Jul 2017 17:09:19 GMT

Bob,

Fully pressing the shutter too quickly can cause bad exposures and out-of-focus shots, especially if you are in AI Servo mode.

I gave one of my sons a T5 in 2014, and he used the shutter as if it were a cell phone. Punch it. I had to show him how to let the camera meter and focus by half-pressing the shutter. He said the camera wouldn't take a picture. He was using One Shot mode, Green [A].

He began using M, "monster" mode as he used to call it, and would get bad exposures shooting AI Servo. He had not yet discovered continuous shooting mode, and was punching the shutter again.

Re: Grossly over exposed images during rapid shooting Canon Mk III

ebiggs1 — Sat, 15 Jul 2017 17:23:53 GMT

You need to call Canon service. This ain't right! All these 'guesses' will get you nowhere fast.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Bundu — Sun, 16 Jul 2017 06:33:01 GMT

Thank you all those who have contributed, I appreciate your views, comments and suggestions. I was hoping that someone in the forum would have come accross the same malfunction and advised how it was resolved. This camera is not 3 months old and the problem maybe unique. I don't believe it is an operator problem, I believe that since it is so new and that I have had this malfunction on a number of occasions, it is a mechanical fault, so I think it is an issue for Canon. So I shall close this dialogue, and report back once the problem has been resolved. Thanks.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Bundu — Sun, 16 Jul 2017 06:43:44 GMT

Thanks ebiggs1, that is what I intend to do.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Mr_Fusion — Mon, 07 Aug 2017 18:52:40 GMT

I too get the same problem occasionally. I have noticed it on my XT, and when I got my T5, the same thing. I just got a T6i in May and yup, same thing. Mine though is not as extreme as yours.

On Sunday I took three shots within a minute of a softball catcher with the T5. ISO fixed at 400, Aperture fixed at 8.0. On the first shot, the shutter was 640, the second, was 1000, and the last was 320. It was a lightly cloudy day and the shadows are very strong on each, suggesting no cloud cover.

Other times I done burst and seen similar deviations within the burst.

I'm baffled by why.