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Thread: Sensor size and light gathering capability

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    Default Sensor size and light gathering capability

    Two different size sensors (518.94mmsq vs 328.56mmsq) with pixels of the size, e.g. both 5.7m, obviously the former will have higher pixel count
    Taking that every other things are the same, will the larger sensor allow a brighter exposure.

    I am curious if APS-H sensor will use a faster shutter speed than APS-C sensor camera to produce the same exposure, given that ISO and Aperture are the same.
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    Senior Member Override2Zion's Avatar
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    Default Re: Sensor size and light gathering capability

    Quote Originally Posted by woeilee View Post
    Two different size sensors (518.94mmsq vs 328.56mmsq) with pixels of the size, e.g. both 5.7m, obviously the former will have higher pixel count
    Taking that every other things are the same, will the larger sensor allow a brighter exposure.

    I am curious if APS-H sensor will use a faster shutter speed than APS-C sensor camera to produce the same exposure, given that ISO and Aperture are the same.
    That is not true, if that is true, it will defeat the entire point of metering. Sensor size will allow a larger area to be exposed through the lens but not more light. Since each photosite on the sensor works independently to "collect" light, having a larger sensor will only mean you can
    1) have more space between photosites (larger gap = less interference = less noise)
    2) pack more photosites onto the sensor (more photosites = capable of more pixels after interpolation)
    3) more space to arrange additional photosites to extend dynamic range (like the Fuji S5Pro)
    Last edited by Override2Zion; 16th December 2010 at 08:10 PM.
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    Default Re: Sensor size and light gathering capability

    Quote Originally Posted by Override2Zion View Post
    1) have more space between photosites (larger gap = less interference = less noise)
    i tot larger gap between photosites = smaller photosites = more noise due to the surface area being smaller?

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    Senior Member Override2Zion's Avatar
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    Default Re: Sensor size and light gathering capability

    Quote Originally Posted by ExplorerZ View Post
    i tot larger gap between photosites = smaller photosites = more noise due to the surface area being smaller?
    Larger gap simply means the photosites are spaced further apart, the photosites can still be larger in size.

    Small sensor, small gap, small photosites, same megapixel
    o o o o
    o o o o
    o o o o

    Large sensor, bigger gap, bigger photosites, same megapixel
    O O O O
    O O O O
    O O O O

    Bigger photosite = More light can enter = Better Signal-Noise Ratio
    Larger gap between photosite = Less heat & interference = Less noise = Better Signal-Noise Ratio

    Either way, we achieve IQ improvement. Hope this explains better.
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    Default Re: Sensor size and light gathering capability

    eh since TS is talking about same density sensor, doesn't the larger gap means smaller photosite? either way, one will decrease the surface of the other?

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    Senior Member Override2Zion's Avatar
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    Default Re: Sensor size and light gathering capability

    TS gave a scenario of 2 sensors of different size with same photo site sizes, there can be 2 variables left
    1) Assuming, photo sites are pack at the same density (no of photo sites per square unit), you will achieve more pixel count, no improvement in IQ
    2) Assuming you drop the photo site density but increase the distance between each site, you will achieve better noise control and possibly increase in pixel count

    Either way, in neither scenarios will allow you to capture a MUCH brighter image on the same shutter, ISO, aperture settings.
    Last edited by Override2Zion; 16th December 2010 at 09:09 PM.
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    Senior Member Override2Zion's Avatar
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    Default Re: Sensor size and light gathering capability

    Quote Originally Posted by ExplorerZ View Post
    eh since TS is talking about same density sensor, doesn't the larger gap means smaller photosite? either way, one will decrease the surface of the other?
    If you read closely on TS assumptions, there was no mention of density
    "with pixels of the size, e.g. both 5.7m, obviously the former will have higher pixel count ". My interpretation here is that higher pixel count does not equal to same pixel density. No hostility intended bro, just to clarify my interpretations.
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    Default Re: Sensor size and light gathering capability

    Quote Originally Posted by woeilee View Post
    Two different size sensors (518.94mmsq vs 328.56mmsq) with pixels of the size, e.g. both 5.7m, obviously the former will have higher pixel count
    Taking that every other things are the same, will the larger sensor allow a brighter exposure.

    I am curious if APS-H sensor will use a faster shutter speed than APS-C sensor camera to produce the same exposure, given that ISO and Aperture are the same.
    Short answer: Nope.

    Long answer: You may get higher ISO capabilities, and the difference in perspective when using the same lens on a APS-H vs. APS-C.

    But other than that, no change in the metering. Light is still light.
    Alpha

  9. #9

    Default Re: Sensor size and light gathering capability

    Quote Originally Posted by Override2Zion View Post
    Larger gap simply means the photosites are spaced further apart, the photosites can still be larger in size.

    Bigger photosite = More light can enter = Better Signal-Noise Ratio
    Larger gap between photosite = Less heat & interference = Less noise = Better Signal-Noise Ratio

    Either way, we achieve IQ improvement. Hope this explains better.
    Thanks for this explanation.

    Quote Originally Posted by Override2Zion View Post
    TS gave a scenario of 2 sensors of different size with same photo site sizes, there can be 2 variables left
    1) Assuming, photo sites are pack at the same density (no of photo sites per square unit), you will achieve more pixel count, no improvement in IQ
    2) Assuming you drop the photo site density but increase the distance between each site, you will achieve better noise control and possibly increase in pixel count

    Either way, in neither scenarios will allow you to capture a MUCH brighter image on the same shutter, ISO, aperture settings.
    Many thanks Override2Zion, I am actually thinking of (1).

    Quote Originally Posted by Override2Zion View Post
    If you read closely on TS assumptions, there was no mention of density
    "with pixels of the size, e.g. both 5.7m, obviously the former will have higher pixel count ". My interpretation here is that higher pixel count does not equal to same pixel density. No hostility intended bro, just to clarify my interpretations.
    Actually I am looking at same pixel density of 2 different size sensors. If each individual is collection a unit of light, same pixel density in larger sensor means more total pixel available to collect more unit of light?

    Quote Originally Posted by Rashkae View Post
    Short answer: Nope.

    Long answer: You may get higher ISO capabilities, and the difference in perspective when using the same lens on a APS-H vs. APS-C.

    But other than that, no change in the metering. Light is still light.
    Thanks Rashkae.
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    Default Re: Sensor size and light gathering capability

    According to DXO, lenses with wide aperture like f1.2 may cause light fall-off. This is another interesting aspect that shows the complexity of DSLR sensors and their ability to capture light through lenses.

    http://www.dxomark.com/index.php/en/...s/F-stop-blues
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