1. Brijesh Langalia's Avatar
    I have L730 and my friend have L640xl.
    Over same manual camera setting and auto setting we took so many photo in sunlight and also in low light.
    Many times we found poor colour production and grainy picture in L640xl.
    Is this happened because of low/poor sensors used in L640xl to make it cheap?
    05-21-2015 12:18 PM
  2. gpobernardo's Avatar
    I think it boils down to the difference in the relationship between the sensor size and the sensor resolution of these two phones.

    The L640XL has a 13.0MP 1/3 inch sensor.
    The L730 has a 6.7MP 1/3.4 inch sensor.

    The fraction in the sensor size basically says: the smaller the denominator, the larger the sensor. Hence, the L640XL has a slightly larger sensor than the L730, but notice how the resolution of the L640XL is almost twice the resolution of the L730. This means that the "light buckets"* in the sensor of the L730 are larger than that in the L640XL. Larger "light buckets" are more sensitive than smaller "light buckets", since larger ones can catch more light.

    When a sensor cannot catch enough light, adjustments are made, such as increasing ISO level (e.g. from ISO-100 to ISO-400) and the signal is amplified. With signal amplification comes noise amplification. This results in the graininess of the photos.

    There could be something else going on, but this is most likely the reason why the L730 produces photos with less noise compared to those produced by the L640XL. Nonetheless, these two phones should perform almost equally under bright day light (where signal amplification is rarely needed).

    *- Each light bucket (or a certain cluster of buckets) translate to "1 pixel", in a way.
    RumoredNow likes this.
    05-21-2015 12:53 PM
  3. Brijesh Langalia's Avatar
    I think it boils down to the difference in the relationship between the sensor size and the sensor resolution of these two phones.

    The L640XL has a 13.0MP 1/3 inch sensor.
    The L730 has a 6.7MP 1/3.4 inch sensor.

    The fraction in the sensor size basically says: the smaller the denominator, the larger the sensor. Hence, the L640XL has a slightly larger sensor than the L730, but notice how the resolution of the L640XL is almost twice the resolution of the L730. This means that the "light buckets"* in the sensor of the L730 are larger than that in the L640XL. Larger "light buckets" are more sensitive than smaller "light buckets", since larger ones can catch more light.

    When a sensor cannot catch enough light, adjustments are made, such as increasing ISO level (e.g. from ISO-100 to ISO-400) and the signal is amplified. With signal amplification comes noise amplification. This results in the graininess of the photos.

    There could be something else going on, but this is most likely the reason why the L730 produces photos with less noise compared to those produced by the L640XL. Nonetheless, these two phones should perform almost equally under bright day light (where signal amplification is rarely needed).

    *- Each light bucket (or a certain cluster of buckets) translate to "1 pixel", in a way.
    THANKS for sharing ur knowledge about sensor size .....
    But I heard many problems regarding to grainy pics from L640xl...
    Is that a drawback of L640xl?
    05-21-2015 01:52 PM
  4. gpobernardo's Avatar
    THANKS for sharing ur knowledge about sensor size .....
    But I heard many problems regarding to grainy pics from L640xl...
    Is that a drawback of L640xl?
    Indirectly, yes. Going back to the sensor size, the more accurate answer to your question would be: "It is a drawback of having a higher resolution but a relatively small sensor; it just so happens that the L640XL has such a sensor."

    It's not always resolution that counts; the physical size of the sensor must also be considered.

    Graininess in photos is caused by signal amplification. Signal amplification is needed when the sensor isn't sensitive enough to light. Sensors lose sensitivity when the "light buckets" on the surface of the sensor aren't large enough. Higher resolution sensors mean that there are more "light buckets" on the surface of the sensor, but if the physical size of the sensor isn't large enough then the light buckets also won't be large enough. Hence, such a sensor would most likely produce grainy photos at lower lighting conditions.
    05-21-2015 10:11 PM

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