Thanks Ken, that actually made sence.
Now, would it be possible to add some sort of fine grain to the sensor
so the reflected light is acattered as with film , but the light
entering the sensor still produces a sharp and crisp image? Otherwise I
see your live reading option as best feasible in the near future.
Wiliam
> -----Oorspronkelijk bericht-----
> Van: Ken Norton [mailto:ken@xxxxxxxxxxx]
> Verzonden: vrijdag 19 juni 2009 19:47
> Aan: Olympus Camera Discussion
> Onderwerp: Re: [OM] RANT: Sample images taken with EP-1
>
>
> >
> > I really do not see why. Sure, the sensor should not reflect much
> > light, but how hard can it be to compute the amount of
> light that has
> > fallen onto the sensor when you know how reflective it is? Even if
> > reflection is only .1% this seems verye feasable to me. For
> me It is
> > still a big miss in all DSLR's, especially coming from Olympus.
> >
> > Someone care to elaborate?
> >
>
>
> It is actually quite difficult as the sensor is more "mirror
> like" than film. Film has a very smooth scattering effect
> (matte surface) and is easy to measure and gives consistent
> meter readings regardless of the position of the light in the
> picture or whether the bright spots are small or large.
>
> A sensor, being more mirror like, doesn't have this
> scattering effect and is a high gloss surface. As such, the
> position and diameter of the bright spots in the image are
> neither predictable or consistent.
>
> For example go into your bathroom with a flashlight (torch).
> Turn the lights off and look at the mirror. Now take the
> flashlight and point it at the yourself in the reflection.
> Notice how bright the flashlight is? Now point it elsewhere
> at the mirror. The reflected light is much dimmer because it
> is no longer pointed at your face. Now, turn around and face
> the bathroom wall. Do exactly the same thing by pointing the
> flashlight directly in front of you and then to the side a
> bit. The brightness remains about the same (depending on paint type).
>
> This is what is happening inside the camera. A light-reading
> sensor in the floor of the mirror-box is pointed at the
> imaging sensor. But since the imaging sensor surface is
> mirror like, the light-reading sensor ends up seeing the
> bottom of the mirror and none of the light coming through the lens.
>
> The only practical solution is to live-read the imaging
> sensor. I suspect that the next generation of live-view
> imaging sensor will be shutterless. Without a shutter, the
> sensor will receive a purge command at the start of the
> exposure and then will dump to the interline rails at the end
> of the exposure. Or the sensor will have a fixed read rate
> of 1000 frames per second and exposures longer than that will
> be a cumulative stack of images for the duration of the
> exposure. As the sensor requires no shutter and light-levels
> are read dynamically off the main imaging-sensor, there is no
> need for a parallel light-reading sensor system.
>
> Or another possiblity is a hybrid sensor--one where there are
> pixels scattered throughout the imaging-sensor and read and
> cleared at a high rate as compared to the imaging pixels
> which are more traditional.
>
> AG
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