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Mechanics of exposure??

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  • Mechanics of exposure??

    I assume that this camera has a focal plane shutter - or does it rely of grabbing the contents of the sensor when the shutter release is pressed.

    If a physical shutter is involved then when the shutter release is pressed then I assume the following sequence of events occurs.

    Exposure settings stored for use
    Shutter is closed
    Sensor is cleared of any information left in it from the live view
    Shutter is activated exposing the sensor for the required time, as well as stopping down the lens.

    After the shutter is closed the data on the sensor is written away to be processed and stored on the memory card.

    The shutter is then opened for the sensor to display the scene to the live view viewfinder.

    Is this valid description of the process.

    What is the lag time from pressing the shutter release to the exposure taking place?

    In the past with non DSLR cameras where the above process took place the subject had often moved out of the picture. How does the new camera perform?

    Thanks for any info - Just curious!
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  • #2
    Re: Mechanics of exposure??

    I dunno, I go to all that trouble to write articles about the new camera and nobody reads them!

    http://fourthirds-user.com/2013/09/o...plained_.php/h

    Ian
    Last edited by Ian; 14th September 2013, 02:19 PM. Reason: Correction! Camera not 'computer'!
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    • #3
      Re: Mechanics of exposure??

      Thanks for the pointer
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      • #4
        Re: Mechanics of exposure??

        I think your description of the exposure/shutter cycle is essentially correct, Derek.

        I don't have a figure for the shutter lag, but it is basically not noticeable. Olympus does offer a figure for the latency between subject movement and the same movement in the electronic viewfinder - 29ms.

        Which camera model do you currently use? Maybe I can relate the E-M1 responsiveness to that?

        Ian
        Founder and editor of:
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        • #5
          Re: Mechanics of exposure??

          Just an interesting tit bit of information, it takes 120ms from the time light enters your eyes for it to travel to your visual cortex. And that's just the time for the electrical signal to reach. It still has to be processed!!

          I suppose not really relevant except to put Ian's figure of 29ms in context but it blew my mind when I first found out: everything you see as "now" happened at least 120ms ago.

          P.S. if anyone is wondering where the figure comes from, it's a medical test called visual evoked potential and is a test of the conduction along your optic nerve.

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          • #6
            Re: Mechanics of exposure??

            Originally posted by josephlck View Post
            Just an interesting tit bit of information, it takes 120ms from the time light enters your eyes for it to travel to your visual cortex. And that's just the time for the electrical signal to reach. It still has to be processed!!

            I suppose not really relevant except to put Ian's figure of 29ms in context but it blew my mind when I first found out: everything you see as "now" happened at least 120ms ago.

            P.S. if anyone is wondering where the figure comes from, it's a medical test called visual evoked potential and is a test of the conduction along your optic nerve.
            Interesting

            Obviously we all experience what seems to be a lag-free world so it would seem that the natural lag is compensated for by our brains.

            The viewfinder lag of 29ms will be added on top of the human lag...

            Ian
            Founder and editor of:
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            • #7
              Re: Mechanics of exposure??

              Originally posted by Ian View Post
              Obviously we all experience what seems to be a lag-free world ...
              I did read somewhere that when playing tennis you start to hit the ball before it has even come your side of the net. Clearly we all have a predictive capacity that can adjust for "lag".

              The main reason why I invested in an E-M5 was that my elderly P&S suffered not only from a slowish focus but also shutter lag - the time taken once focus had been established to actually exposing for the picture. Although this is now very quick on modern mirrorless cameras (Olympus and Panasonic being especially good across the entire range) I'm sure that it would put the 29ms EVF lag into perspective.
              Cameras: E-M5, E-PM2, OM40, OM4Ti
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              • #8
                Re: Mechanics of exposure??

                I use an E5, my comments/concerns are based on my pre DSLR days when the cameras were very slow - to see if a camera was suitable I would press the shutter when a walking person passed a marker on the pavement and then see what was on the picture - on many times the person was out of the frame. When I was taking lots of dog pictures I managed to get lots of pictures of dog's tails. Hence a move to the E20 and then to the E1 and managed to get the head and tail of the dog in the same picture.
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                • #9
                  Re: Mechanics of exposure??

                  Originally posted by DerekW View Post
                  I use an E5, my comments/concerns are based on my pre DSLR days when the cameras were very slow - to see if a camera was suitable I would press the shutter when a walking person passed a marker on the pavement and then see what was on the picture - on many times the person was out of the frame. When I was taking lots of dog pictures I managed to get lots of pictures of dog's tails. Hence a move to the E20 and then to the E1 and managed to get the head and tail of the dog in the same picture.
                  OK, well the E-M1 will be just as responsive, maybe more so, than an E-1 or your E-5.

                  Ian
                  Founder and editor of:
                  Olympus UK E-System User Group (http://e-group.uk.net)
                  Four Thirds User (http://fourthirds-user.com)
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