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Thread: Megapixel and ISO

  1. #1

    Default Megapixel and ISO

    Just popping a question probably I have already answered myself. As we all know that having higher pixel count and shooting at higher ISO is asking for noise. Anyway, taking an example below,

    14 MP + @1600 ISO = Noisy Pic
    Lowering MP to say 8 MP + @1600 ISO = Lesser Noise Pic? Due to lower resolution the sensor is capturing.

    Then how about shooting @ 14MP, resizing image to size of a 8MP. Does it makes a difference?

    Thanks.

  2. #2
    Moderator Octarine's Avatar
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    Default Re: Megapixel and ISO

    The MP itself are not the only factor. The pixel density as well as the noise reduction algorithms will also contribute to the result. Haven't seen any camera where you can adjust the MP. You might not use the entire sensor - but the pixel density remains constant.
    EOS

  3. #3

    Default Re: Megapixel and ISO

    Sony Alpha's Full Frame DSLR A900 and A850 can switch between FF and APS-C modes, utilizing different size of the sensor.

    However I dont think there will be any difference to the ISO noise though.

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    Default Re: Megapixel and ISO

    Quote Originally Posted by gravism View Post
    Just popping a question probably I have already answered myself. As we all know that having higher pixel count and shooting at higher ISO is asking for noise. Anyway, taking an example below,

    14 MP + @1600 ISO = Noisy Pic
    Lowering MP to say 8 MP + @1600 ISO = Lesser Noise Pic? Due to lower resolution the sensor is capturing.

    Then how about shooting @ 14MP, resizing image to size of a 8MP. Does it makes a difference?

    Thanks.
    It won't make a difference, look at it this way...

    Regardless of what "quality" you've set your camera to capture the image at, the camera is still going to take the same RAW image on the sensor and work on it (DX mode on FX Nikon cameras is an exception, but that's not even the same FOV). So even if you set your file size to small, all you're doing is aggregating the original RAW image to produce a smaller resolution picture. There's no difference doing this on camera as compared to on your computer, and your computer might just do it better as well depending on the resizing algorithm.

  5. #5

    Default Re: Megapixel and ISO

    A member has tried images of same ISO setting at different shooting image size setting on the camera. No different.

  6. #6

    Default Re: Megapixel and ISO

    the mp should not afffect the noise level, as even if u resize, the same data is preserved, just resized, which may look less noisy due to the smaller size of the image. the main factor contributing to low noise image would be pixel density. sensor size and the algorithm used when processing the taken image in the camera

  7. #7

    Default Re: Megapixel and ISO

    to answer your question, no, there is no difference. megapixels are megapixels. what the camera does is resize the image for you, that's it.

  8. #8

    Default Re: Megapixel and ISO

    Quote Originally Posted by gravism View Post

    14 MP + @1600 ISO = Noisy Pic
    Lowering MP to say 8 MP + @1600 ISO = Lesser Noise Pic? Due to lower resolution the sensor is capturing.

    Thanks.
    is it true it will help to reduce noise if lower the mp of the camera, maybe i should try when i am free.

  9. #9
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    Default Re: Megapixel and ISO

    Quote Originally Posted by takengo2003 View Post
    is it true it will help to reduce noise if lower the mp of the camera, maybe i should try when i am free.
    You can try when you are free, or you can also try to read the replies :P

  10. #10
    Moderator Octarine's Avatar
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    Default Re: Megapixel and ISO

    Quote Originally Posted by takengo2003 View Post
    is it true it will help to reduce noise if lower the mp of the camera, maybe i should try when i am free.
    You are not lowering the MP - you just simply don't use all pixels by cutting off outer parts and only using the center part of the sensor. No change at all, no gain at all.
    EOS

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    Default Re: Megapixel and ISO

    if reducing MP can sove noise issue.. i will take at 1mp @ ISO12800 ... haha... sadly it does not work this way la like what the above replies says..

    anyway, there are software to help reduce noise.. was it noisekiller or something? i never tried..

  12. #12

    Default Re: Megapixel and ISO

    alright. Thanks all bros here. =D
    My overall understanding now here is..

    1. It's the pixel density & NR that counts. It is still using the same but lesser part of the sensor.
    2. Lowering MP is like helping you to resize in your camera instead of doing it on PC.

    New knowledge everyday. Cheers!

  13. #13

    Default Re: Megapixel and ISO

    think there are alot of reading material online pertaining to noise VS sensor size.

    basically the bigger sensor = bigger pixel (bigger surface to pick up the light) [only true if your pixel count is a constant]

    bigger pixel when light fall on it the signal it output will be high compare to noise signal in the sensor. (ie. u catch rain water(light) with a basin VS using a glass. and later introduce 100ml or oil (noise) to the water u captured, the ratio of water VS oil is how good your high ISO is going to be.

    thats y FF sensor normally have better ISO performance as their individual pixel is bigger. but technology advancement is changing the scale.

    Pixel density VS noise is a better comparision to rate which camera/sensor is better in terms of ISO.
    D80/D700 18-135/17-50/14-24/24-70/70-200/70-300/50/60 SB600/900

  14. #14

    Default Re: Megapixel and ISO

    Quote Originally Posted by TsQ View Post
    if reducing MP can sove noise issue.. i will take at 1mp @ ISO12800 ... haha... sadly it does not work this way la like what the above replies says..

    anyway, there are software to help reduce noise.. was it noisekiller or something? i never tried..
    You referring to Noise Ninja (http://www.picturecode.com/)?

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    Default Re: Megapixel and ISO

    ya ya noise ninja .. haha duuno how i can get it to become noisekiller.. i guess ninja kills.. :P

  16. #16
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    Default Re: Megapixel and ISO

    noise ninja is good, but dont over do it. over doing will make the people in it look so "plastic"... haha. tested over-doing and they look like wax figures

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    Default Re: Megapixel and ISO

    Quote Originally Posted by Dylan1987 View Post
    noise ninja is good, but dont over do it. over doing will make the people in it look so "plastic"... haha. tested over-doing and they look like wax figures
    is this the same feature as Photoscape's Noise reduction / SMart Blur ?

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    Default Re: Megapixel and ISO

    Quote Originally Posted by Octarine View Post
    The MP itself are not the only factor. The pixel density as well as the noise reduction algorithms will also contribute to the result. Haven't seen any camera where you can adjust the MP. You might not use the entire sensor - but the pixel density remains constant.
    eh what you talking about is cropping (FF to APS-C or similar), not really resizing. and almost all camera enable the user to shoot at different dimension aka MP, even the cheapest PnS have that.

    by resizing, the image probably look cleaner when compared pixel to pixel, just like why most of the web images always look cleaner than at their original copy.

  19. #19
    Member Dylan1987's Avatar
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    Default Re: Megapixel and ISO

    Quote Originally Posted by TsQ View Post
    is this the same feature as Photoscape's Noise reduction / SMart Blur ?
    i am not quite sure about that... mine is the external plugin for photoshop cs4

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