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EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

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    EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

    Had a Canon EOS 5D MK3 for a few months now, bought it used with really low shutter count (8K) but I'm finding about half the time the camera underexposes between 1 and 2 stops, regardless of the mode, or metering mode. If I'm in Aperture Priority, or Shutter Priority it underexposes no matter what metering mode I use, be it: evaluative, spot, centre weighted. Same in full manual mode too: I set the exposure based on the cameras metering modes.

    In the studio with strobes and a flash meter it is spot on, but I'm in full manual mode and using a flash meter for readings.

    Is there an in-camera setting (perhaps a factory default setting) that needs to be changed to prevent this? Anybody else finding this?

    Like I said, only does it about half the time.

    #2
    Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

    That's a difficult one....as its only half the time.

    Have you flicked through the info screens to check there is no underexposure set......I expect you have checked that

    Is it always the same lens....is the lens failing to close the aperture down.....what does it look like on 'live view' with exposure preview enabled?
    Brian Vickers LRPS

    brianvickersphotography.com

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      #3
      Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

      Thanks brainvickers. Yes, checked their is no exposure-compensation set. Two different lenses, 24-70 f2.8 L and 70-200 f2.8 L. I suppose if the aperture was failing to close down it would be over-exposed, not under like I'm getting. This would suggest the aperture blades are stuck in a closed down position, which they are not. I will check the 'live view' mode. How do I assure 'exposure preview' is turned on in live view?

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        #4
        Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

        Just checked Live View with 'exposure preview' and it looks a stop under exposed there too.

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          #5
          Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

          Ok, more information. Putting it on your tripod and pointing it at a neutral reference scene I put camera in AV mode and set aperture to f8 and noted the shutter speed suggested when half-pressing your shutter button.

          Then switched to M, sticking with f8 and noted the shutter speed that I needed to get the meter to read bang in the middle.

          Following the above instructions in AP at F8 the shutter speed was 0.6 seconds and in manual, to get pointer to centre (correct exposure) it was 13th of a second. In manual mode I have to dial it 3 stops over-exposed to get 0.6 seconds. This does not make sense.

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            #6
            Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

            I wonder if you have discovered why the camera was available used?
            John Liddle

            Backwell, North Somerset - "Where the cider apples grow"

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              #7
              Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

              Hi, I have a 5d3 that I bought about 18 months ago, used from Clifton Cameras. It underexposed by about 2/3 -1 stop. I spoke to C C who asked me to return it and they returned to Canon for me under the warranty (good service frim CC). Canon checked it out and said all was ok. I still have the camera, a great camera, and now simply add 2/3 stop when shooting using Ex comp. I know this doesn’t rectify the problem but it is an easy workaround that becomes second nature. Just my two penny worth

              Guy
              https://www.flickr.com/photos/123741420@N06/

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                #8
                Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

                It looks like a fault to me but I'm no expert....you could try asking Technical Advice Service at the magazine via the Contact tab on the main web site...

                mailto:advice@eos-magazine.com?Subject=Technical%20advice%20request% 20via%20eos-magazine.com
                Brian Vickers LRPS

                brianvickersphotography.com

                Comment


                  #9
                  Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

                  Hmm, I have a 5D3 and this isn't something I have experienced. I'll have a play over next few days and see if I can reproduce the issue.
                  Canon 5D3, 7D2, 60D, Canon 70-200L f2.8 IS II, Canon 300 f4L IS, Canon 16-35 f4 L, Canon 24-105mm f/4L IS USM, Canon 1.4 MkIII extender, Sigma AF 10-20mm f/3.5 EX DC HSM, Sigma 150-600 Contemporary, Tamron SP AF 70-300 F/4-5.6 Di VC USD, Canon EF-S 18-55mm 1:3.5-5.6 IS
                  https://www.flickr.com/photos/16830751@N03/

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                    #10
                    Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

                    CambsCreative - does the effect show itself both when the camera is on a tripod and when hand held?

                    I ask because, when not hand held, the viewfinder eyepiece should be covered with the little rubbery plastic thingy that comes on the camera strap, in order to prevent stay light entering the camera and upsetting the metering (See p. 187 of the MkIII manual). This says images will come out dark if you don't do this, but it is not necessary in live view mode.
                    John Liddle

                    Backwell, North Somerset - "Where the cider apples grow"

                    Comment


                      #11
                      Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

                      I also own a 5D Mk III but have had no such problem. At first I thought it may be down to technique but you seem to have covered all bases!

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                        #12
                        Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

                        Ok, final update on this. Yes, I use the black rubber eye cover on tripod.

                        Anyway, I bought an 18% grey card and stuck it on my wall and put camera on tripod, filled frame, put rubber eye cup cover in place and took a reading in Aperture Priority. I then went in to full Manual mode and chose the same shutter speed and aperture that resulted in my Aperture Priority reading and the little exposure meter digital needle was bang in the middle, so both exactly the same, as I'd expect them to be.

                        When I then zoom out and point the camera to a different scene in the room, still the same wall and falling under the same light as the grey card, only now my kitchen table (which is pine wood and much lighter than 18% grey) with some items on it, the Aperture Priority mode now chooses a faster shutter speed, by about two stops, resulting in underexposure. If I then go back into Manual and use the same settings that were read off the grey card and re-take the image, it is perfectly exposed with a nicely balanced reading on the Histogram.

                        The result of my findings is that all the metering modes on the camera: Evaluative, centre weighted, spot, etc, all underexpose by 2 stops on average for most of the scenes I shoot, landscape, portrait, buildings, anything outdoors. The only time I get a perfect exposure is doing studio strobe work with a flash meter.

                        While doing this grey card test I also took two readings with my Sekonic L-308X meter in both incident and reflected modes and it came back with the same as the Canon, F4 with a shutter speed of 1/4th second at 100 ISO, which tells me all is good.

                        I've deduced that I can only really use 'spot metering' with this camera and that I must aim the spot at something that is as close to 18% grey as possible and even then to check the histogram to make sure it is balanced and not all leaning too far to the left.

                        Anyway, appears there is no fault, just the 5D MK3 is really fussy and there is no room for anything outside 18% grey as far as the cameras built in exposure sensor is concerned. But then again, built-in exposure meters that take 'reflective' light readings are never going to be spot on, but the Canon just seems to be very unforgiving, unlike my old Nikon D3s, which did a much better job.

                        So, to re-cap, I just have to use spot metering and aim for subjects in the scene that look close to 18% grey and then hit the exposure lock button on the back of the camera, re-compose, take shot and check histogram.

                        Comment


                          #13
                          Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

                          I had a 5D3 for a number of years and took 35,000 pictures using various modes and never had this problem. Sounds like a fault. Having said that I did find that Lightroom occasionally produced weird results with files from this camera but when processed in DPP there was no problem. Still think that you have a faulty camera.
                          Alan

                          No longer using Canon but still teaching new Canon users (and others) the gentle art of Photography.

                          http://www.springfield-photography.com/

                          Comment


                            #14
                            Re: EOS 5D MK3 underexposing by 1 or 2 stops - anybody else finding this?

                            I agree, Alan. Will put up with it and work with Sekonic meter in the meantime as that is acurate.

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