Is 7MP too much for a beginner (intermediate) camera?

Discussion in 'Digital Photography' started by Susan P, Dec 17, 2005.

  1. Susan P

    Ron Hunter Guest

    Susan P wrote:
    > Can you folks advise me please.
    >
    > The biggest pictures I will ever need to print will be 10 x 8 at
    > at reasonable to good quality. Here in the I am looking at some
    > good prices for the CASIO EX-Z120 digital camera. It can be
    > bought for about 150 pounds.
    >
    > See http://www.steves-digicams.com/2005_reviews/ex-z120.html
    >
    > Although it's a beginner's camera (maybe intermediate user) it is
    > a whopping 7 megapixels. Isn't this getting to be too much? In
    > fact could 7 MP actually be worse than a 4 MP camera?
    >
    > Am I right in thinking that if you have so many megapixels then
    > it:
    > takes longer to compress the image (to jpeg)
    > takes longer to save uncompressed images
    > needs more memory capacity
    >
    > And probably (I don't really know - help me here) gives a worse
    > result than a 4 megapizel camera because the compression for 7
    > megapixels may sample BETWEEN pixels. (Am I getting this right?)
    >
    > Anyway, my question to you folks is: can I have too many
    > megapixels such that they become a hindrance? Is this CASIO EX-
    > Z120 with 7 MP too much for me?


    There is nothing really wrong with going for more pixels, all other
    factors being equal. It gives, at least, more freedom at the cropping
    phase of editing. There may be a tradeoff with number of pixels and
    noise levels at higher than ISO 100, however as the size of the sensor
    usually stays the same, even thought it is divided into more pixels.
    Ron Hunter, Dec 18, 2005
    #21
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  2. In article <43a4dc21$0$15732$>,
    dj_nme <> wrote:
    >Bill Funk wrote:
    >> On Sat, 17 Dec 2005 17:46:20 +0000 (UTC),
    >> (Gregory L. Hansen) wrote:
    >>
    >>
    >>>In article <>,
    >>>Bill Funk <> wrote:

    ><snip>
    >>>I'd think you could do in software what a larger pixel would do
    >>>physically-- average.

    >>
    >>
    >> That sounds like making more information out of nothing.
    >> If the signal coming out of the sensel is low, you can't average it
    >> with anything to raise it; you need to amplify it.
    >> A larger selsel will start out with more signal in the first place.

    >
    >To me, this sounds like downsampling or making the image smaller by
    >resampling at a lower resolution.
    >It does work (gets rid of visible noise), but all of the information in
    >the averaged out pixels is lost (several merged together to make one
    >smaller pixel) and so you may as well have started with a lower
    >resolution camera that has less image noise to start with.


    Sure. But if the other option would have been to use a camera with lower
    MP to get less noise, you wouldn't have the option of not averaging the
    noise out in software.

    --
    "Pain is temporary, quitting lasts forever" -- Lance Armstrong
    Gregory L. Hansen, Dec 18, 2005
    #22
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  3. Susan P

    Bill Funk Guest

    On Sun, 18 Dec 2005 17:13:51 +0000 (UTC),
    (Gregory L. Hansen) wrote:

    >In article <43a4dc21$0$15732$>,
    >dj_nme <> wrote:
    >>Bill Funk wrote:
    >>> On Sat, 17 Dec 2005 17:46:20 +0000 (UTC),
    >>> (Gregory L. Hansen) wrote:
    >>>
    >>>
    >>>>In article <>,
    >>>>Bill Funk <> wrote:

    >><snip>
    >>>>I'd think you could do in software what a larger pixel would do
    >>>>physically-- average.
    >>>
    >>>
    >>> That sounds like making more information out of nothing.
    >>> If the signal coming out of the sensel is low, you can't average it
    >>> with anything to raise it; you need to amplify it.
    >>> A larger selsel will start out with more signal in the first place.

    >>
    >>To me, this sounds like downsampling or making the image smaller by
    >>resampling at a lower resolution.
    >>It does work (gets rid of visible noise), but all of the information in
    >>the averaged out pixels is lost (several merged together to make one
    >>smaller pixel) and so you may as well have started with a lower
    >>resolution camera that has less image noise to start with.

    >
    >Sure. But if the other option would have been to use a camera with lower
    >MP to get less noise, you wouldn't have the option of not averaging the
    >noise out in software.


    OK, if what Greg said was that downsampling is the averaging he spoke
    of (it was Grag, right?), then simply using fewer mps would achieve
    lower noise withiout any averaging, which would, I think, mean better
    sharpness in the image. Smaller image, fewer pixels, but thos pixels
    wouldn't be averaged with others to muddle things up.

    --
    Bill Funk
    Replace "g" with "a"
    funktionality.blogspot.com
    Bill Funk, Dec 18, 2005
    #23
  4. Susan P

    dj_nme Guest

    Bill Funk wrote:

    > On Sun, 18 Dec 2005 17:13:51 +0000 (UTC),
    > (Gregory L. Hansen) wrote:
    >>
    >>dj_nme wrote:
    >>>To me, this sounds like downsampling or making the image smaller by
    >>>resampling at a lower resolution.
    >>>It does work (gets rid of visible noise), but all of the information in
    >>>the averaged out pixels is lost (several merged together to make one
    >>>smaller pixel) and so you may as well have started with a lower
    >>>resolution camera that has less image noise to start with.

    >>
    >>Sure. But if the other option would have been to use a camera with lower
    >>MP to get less noise, you wouldn't have the option of not averaging the
    >>noise out in software.

    >
    > OK, if what Greg said was that downsampling is the averaging he spoke
    > of (it was Grag, right?), then simply using fewer mps would achieve
    > lower noise withiout any averaging, which would, I think, mean better
    > sharpness in the image. Smaller image, fewer pixels, but thos pixels
    > wouldn't be averaged with others to muddle things up.


    The only "gotcha" (in my opinion) with starting with a smaller
    resolution camera sensor is that for it to be lower noise than the
    higher resolution one, is that it has to be of the same (or newer)
    "generation".
    By that, I mean that both the high and low res sensors use that same on
    chip processing and the only difference is the actual size of each sensel.
    For example, comparing the sensor in the Minolta Dimage 7 to the sensor
    in the Panasonic FZ5 (even though they are the same output resolution)
    isn't realy fair because the FZ5 sensor uses more recent advances in
    sensor design and manufacture to achieve a less noisey image output.
    dj_nme, Dec 18, 2005
    #24
  5. In article <>,
    Bill Funk <> wrote:
    >On Sun, 18 Dec 2005 17:13:51 +0000 (UTC),
    > (Gregory L. Hansen) wrote:
    >
    >>In article <43a4dc21$0$15732$>,
    >>dj_nme <> wrote:
    >>>Bill Funk wrote:
    >>>> On Sat, 17 Dec 2005 17:46:20 +0000 (UTC),
    >>>> (Gregory L. Hansen) wrote:
    >>>>
    >>>>
    >>>>>In article <>,
    >>>>>Bill Funk <> wrote:
    >>><snip>
    >>>>>I'd think you could do in software what a larger pixel would do
    >>>>>physically-- average.
    >>>>
    >>>>
    >>>> That sounds like making more information out of nothing.
    >>>> If the signal coming out of the sensel is low, you can't average it
    >>>> with anything to raise it; you need to amplify it.
    >>>> A larger selsel will start out with more signal in the first place.
    >>>
    >>>To me, this sounds like downsampling or making the image smaller by
    >>>resampling at a lower resolution.
    >>>It does work (gets rid of visible noise), but all of the information in
    >>>the averaged out pixels is lost (several merged together to make one
    >>>smaller pixel) and so you may as well have started with a lower
    >>>resolution camera that has less image noise to start with.

    >>
    >>Sure. But if the other option would have been to use a camera with lower
    >>MP to get less noise, you wouldn't have the option of not averaging the
    >>noise out in software.

    >
    >OK, if what Greg said was that downsampling is the averaging he spoke
    >of (it was Grag, right?), then simply using fewer mps would achieve
    >lower noise withiout any averaging, which would, I think, mean better
    >sharpness in the image. Smaller image, fewer pixels, but thos pixels
    >wouldn't be averaged with others to muddle things up.


    I guess I don't know whether downsampling is what I suggested. But I'd
    certainly suggest that the user consider doing a weighted average with
    more weight given to the central pixel. I.e. it's possible to choose to
    smooth over the noise just a little bit.

    I've been completely ignoring what someone else suggested, that each pixel
    on the sensor is surrounded by some non-light sensing area. I just wanted
    to acknowledge that.

    --
    "I'm giving you the chance to look fate in those pretty eyes of hers
    and say, 'Step off, bitch. This is my party and you're not invited.'"
    -- Chris Shugart, _Testosterone Magazine_
    Gregory L. Hansen, Dec 19, 2005
    #25
  6. Susan P

    Bill Funk Guest

    On Mon, 19 Dec 2005 18:07:17 +0000 (UTC),
    (Gregory L. Hansen) wrote:

    >In article <>,
    >Bill Funk <> wrote:
    >>On Sun, 18 Dec 2005 17:13:51 +0000 (UTC),
    >> (Gregory L. Hansen) wrote:
    >>
    >>>In article <43a4dc21$0$15732$>,
    >>>dj_nme <> wrote:
    >>>>Bill Funk wrote:
    >>>>> On Sat, 17 Dec 2005 17:46:20 +0000 (UTC),
    >>>>> (Gregory L. Hansen) wrote:
    >>>>>
    >>>>>
    >>>>>>In article <>,
    >>>>>>Bill Funk <> wrote:
    >>>><snip>
    >>>>>>I'd think you could do in software what a larger pixel would do
    >>>>>>physically-- average.
    >>>>>
    >>>>>
    >>>>> That sounds like making more information out of nothing.
    >>>>> If the signal coming out of the sensel is low, you can't average it
    >>>>> with anything to raise it; you need to amplify it.
    >>>>> A larger selsel will start out with more signal in the first place.
    >>>>
    >>>>To me, this sounds like downsampling or making the image smaller by
    >>>>resampling at a lower resolution.
    >>>>It does work (gets rid of visible noise), but all of the information in
    >>>>the averaged out pixels is lost (several merged together to make one
    >>>>smaller pixel) and so you may as well have started with a lower
    >>>>resolution camera that has less image noise to start with.
    >>>
    >>>Sure. But if the other option would have been to use a camera with lower
    >>>MP to get less noise, you wouldn't have the option of not averaging the
    >>>noise out in software.

    >>
    >>OK, if what Greg said was that downsampling is the averaging he spoke
    >>of (it was Grag, right?), then simply using fewer mps would achieve
    >>lower noise withiout any averaging, which would, I think, mean better
    >>sharpness in the image. Smaller image, fewer pixels, but thos pixels
    >>wouldn't be averaged with others to muddle things up.

    >
    >I guess I don't know whether downsampling is what I suggested. But I'd
    >certainly suggest that the user consider doing a weighted average with
    >more weight given to the central pixel. I.e. it's possible to choose to
    >smooth over the noise just a little bit.


    Maybe I'm off base, but I seriously doubt that very many people who
    are trying to make a descicion between 5 or 7 mp are going to take
    "doing a weighted average with more weight given to the central pixel"
    into account.
    But that's just me. :)
    >
    >I've been completely ignoring what someone else suggested, that each pixel
    >on the sensor is surrounded by some non-light sensing area. I just wanted
    >to acknowledge that.


    --
    Bill Funk
    Replace "g" with "a"
    funktionality.blogspot.com
    Bill Funk, Dec 19, 2005
    #26
  7. Susan P

    Chris Down Guest

    "Susan P" <> wrote in message
    news:972F7995CB96172A58@204.153.244.156...
    > Can you folks advise me please.
    >
    > The biggest pictures I will ever need to print will be 10 x 8 at
    > at reasonable to good quality. Here in the I am looking at some
    > good prices for the CASIO EX-Z120 digital camera. It can be
    > bought for about 150 pounds.
    >
    > See http://www.steves-digicams.com/2005_reviews/ex-z120.html
    >
    > Although it's a beginner's camera (maybe intermediate user) it is
    > a whopping 7 megapixels. Isn't this getting to be too much? In
    > fact could 7 MP actually be worse than a 4 MP camera?
    >
    > Am I right in thinking that if you have so many megapixels then
    > it:
    > takes longer to compress the image (to jpeg)
    > takes longer to save uncompressed images
    > needs more memory capacity
    >
    > And probably (I don't really know - help me here) gives a worse
    > result than a 4 megapizel camera because the compression for 7
    > megapixels may sample BETWEEN pixels. (Am I getting this right?)
    >
    > Anyway, my question to you folks is: can I have too many
    > megapixels such that they become a hindrance? Is this CASIO EX-
    > Z120 with 7 MP too much for me?


    I would suggest that your forget about the pixel count and look at the lens
    quality, the optical zoom functions and ergonomics ... in that order.

    Next you need to see what file sizes you get when you shoot at maximum
    resolution and maximum quality. A 7Mp sensor puts out a lot of data and
    some cameras apply a huge amount of compression when saving as JPEG, JPEG
    is a lossy file format, that is is discards some data in saving the file.
    On a 7x5 print, or viewing the whole shot on a PC screen you won't see the
    compression artefacts, but if you crop or enlarge you will. It is worth
    remembering that each successive save as JPEG drops the quality.


    What really matters is what you want to use the pictures for. 2Mp is
    enough to fill a 1600x1280 PC monitor and to give very good 7x5 prints.
    Compact point and shoot cameras only have more pixels than this because they
    can and the marketing men demand it. Marketing alone demands that each
    year the sensors get more and more pixels, that way you can be convinced you
    need a new camera.

    I have a 3 years old Canon A40 2Mp and I get great results from it... I
    also have a Canon 300D with external flash, battery grip, L series lens,, 10
    times the price but for a different use.

    As a guide my 2Mp point and shoot produces JPG files of upto 1.8MB when
    shooting a picture with lots of varied patterns and little repetition. (JPEG
    compression can compress large areas of solid colour or repetition with
    little loss) In this case the Canon is clearly using minimal compression so
    I am getting the pixels I paid for. If you are looking at a 7Mp camera it
    would be expected to produce files of the order of 6.3MB otherwise it is
    losing data in the compression.

    The 6.3Mp DSLR produces JPEG files upto 5.9MB. So again I am happy that I
    am losing little in compression. The RAW files, unprocessed sensor datea,
    are of course bigger.

    Keep an eye on http://www.dpreview.com/reviews/specs/Casio/casio_exz120.asp
    for an review of the specific camera.
    Chris Down, Dec 20, 2005
    #27
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