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

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

  1. Susan P

    Susan P Guest

    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.


    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
    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?
    Susan P, Dec 17, 2005
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  2. Susan P

    Scott W Guest

    You can always reduce the number of pixels in the capture. I question
    then is why not just get a camera that has fewer pixels to begin with?
    The answer is that a 7 MP camera that produces say a 4 MP image will
    produce a sharper 5mp then a 4 MP camera would. This is a bit of a
    generalization but is mostly true.

    There are a lot of things to look for other then the pixel count, how
    does it do in low light, what is the zoom range, how many photos will
    it take on a battery charge, how good do the photos look. Most of this
    is it hard to know about the Casio EX-Z120 since it seem it just came
    out and has not been reviewed yet.

    Scott W, Dec 17, 2005
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  3. Yes, but the processor may be newer or faster
    Yes, but are you expecting RAW in a GBP 150 camera?
    There is some sense in saying that 4MP will be enough. The main problem
    with more MP is higher noise (grain) because of the smaller pixel size.
    On the other hand, the sensors may be newer so the noise slightly less,
    and the noise is finer-grained (because of the smaller pixels) so may be
    slightly less visible. What the greater number of pixels allows you to do
    is to crop your images a little if they were not perfectly framed in the
    first place.

    Be aware that this camera does not have optical image stabilisation - the
    anti-shake DSP is (probably) no substitute. Do not expect noise-free
    images at speeds greater than ISO 100.

    I don't know if it's in the same class or price range, but the 6MP Fuji
    F10 gets good reviews.

    David J Taylor, Dec 17, 2005
  4. Susan P

    Jasen Guest

    You're better off getting a 4 or 5MP camera than the 7MP for that price.
    You will probably find, that a camera for less MP at the same price as the
    one with more MP will produce a little better pics. For an 8x10" you won't
    need more than 4. I'd go a 5 just in case because you never know when you
    might want that slightly bigger print to do your photography more justice.
    Jasen, Dec 17, 2005
  5. Susan P

    Shawn Hirn Guest

    Maybe I am missing something, but why could more information in a photo
    possibly ever be worse than less information? Buy the highest resolution
    camera you can afford. This is true regardless of how much experience
    you have with digital photography. The only exception would be if you
    plan to shoot photos exclusively for web and email media (e.g., eBay) in
    which case, 3MP is fine.
    Shawn Hirn, Dec 17, 2005
  6. Susan P

    Pete Rissler Guest

    One word "Cropping", if the cameras are close in quality, get the one with
    the higher MP.
    Pete Rissler, Dec 17, 2005
  7. My advice is to not worry about MP count. It is only one of many stats
    about a digital camera and I would not rate it the most important.

    Too many is seldom any problem. Too few is not much of a problem these

    Look at the overall results that the camera can give you and ignore the

    While generally high MP count cameras also have better overall designs,
    it is not always so.

    Take a look at several cameras and get them into your hands. How they
    feel to you is an important issue, really. Do your fingers reach the
    controls easily or do you need to stretch for example. Can you see the
    image (viewfinder and or display screen) well?
    Joseph Meehan, Dec 17, 2005
  8. Susan P

    Jim Guest

    No. You might find the vast number of ways to take pictures somewhat
    overwhelming though.
    Jim, Dec 17, 2005
  9. Susan P

    Bill Funk Guest

    If all information were the same, it wouldn't.
    However, not all information is equal. Would you rather take a
    chemistry course from a chemistry expert, or your local pothead?
    In the case of digital cameras, more mp can mean a worse picture
    because of noise; all other things being equal, more mp means less
    area per sensel; the signal must be amplified. Amplification means
    noise. The more amplification (due to a lower initial signal) means
    more noise. This is why P&S cameras, as a rule, have more noise at
    higher ISO settings than DSLRs do.
    So, more mp does not always translate into better pictures.
    There's far more to the equation of picking a good camera (one that
    fills your needs/wants) than simply buying more mps.
    Bill Funk, Dec 17, 2005
  10. Bill Funk wrote:

    A component of the noise is actually present in the "signal" before
    amplification as photon-limited noise. There is a degree of trade-off,
    though, as some non-SLR cameras have faster lenses (f/2.8) than some DSLRs
    fitted with the "Kit" lens (f/5.6), and may have image-stabilised lenses,
    thus allowing longer shutter speeds. IS lenses can be costly for DSLRs.

    Each photographer needs to decide for themselves what equipment best suits
    their particular needs.

    David J Taylor, Dec 17, 2005
  11. I'd think you could do in software what a larger pixel would do
    physically-- average.
    Gregory L. Hansen, Dec 17, 2005
  12. Susan P

    bmoag Guest

    I have the EXZ750 which has the same sensor as the CASIO EX-Z120 and
    probably the same lens, albeit in a smaller form factor camera.
    Don't worry about massive enlargements from this camera because the image
    quality will not routinely support prints larger than 5x7 without a lot of
    I enjoy the 750 because of the size and convenience but these are not high
    quality all purpose cameras comparable to dSLRs or hi end EVF cameras.
    In fact the 7mp sensor is very much overkill: a well designed 3mp camera can
    yield equivalent or better quality images at print sizes up to 5x7. How do I
    know? I have run a few comparisons (not all that many) between the teeny
    Casio and my dying old Nikon 990.
    But I could never put the 990 in my pocket (with room to spare) and that is
    the niche these teensy cameras fill. Image quality for the unsophisticated
    user (which is the majority of the market) is satisfactory. At a particular
    price point a 7mp sensor is an easier sell even if it can not yield
    technically superior images compared to smaller mp count sensor in the same
    bmoag, Dec 17, 2005
  13. You should get the best tools for your craft you can afford. Today
    you may not want or know what to with those pixels but tomorrow you


    "I have been a witness, and these pictures are
    my testimony. The events I have recorded should
    not be forgotten and must not be repeated."

    -James Nachtwey-
    John A. Stovall, Dec 17, 2005
  14. Susan P

    Bill Funk Guest

    On Sat, 17 Dec 2005 17:46:20 +0000 (UTC),
    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.
    Bill Funk, Dec 17, 2005
  15. Susan P

    m Ransley Guest

    I bought a sony W5 my first digital and find I could have used the W7 as
    I enjoy cropping. There are uses for more mp, you can always resize down
    later for more memory. With cropping I often end up with one or 2 better
    photos out of the original. I will find a use for 20 mp when they are
    cheap enough. The new models with all the extra fun features usualy just
    have more mp. Get what you can afford its all about enjoyment.
    m Ransley, Dec 18, 2005
  16. [A complimentary Cc of this posting was sent to
    Shawn Hirn
    Until very recently, adding information (by increasing the pixel
    count) would be accompanied by decreasing the quality of "already
    present" information. This is most probably not applicable anymore
    (at least in some price range).

    There are 2 reasons why increasing pixel count (thus adding the "high
    spacial frequency" information) may decrease the quality (read: S/N
    ratio) of the "low-spacial frequency" information:

    a) provided the size of transistors is the same, they take more area
    of the cell, thus decrease the fill factor, thus QE of the sensor
    (this increases the electron noise);

    b) there is a component of the noise which is independento of the
    size of the cell: readout noise. More pixels means more readout

    "a" is applicable to toy sensors (such as on the camera you discuss,
    where the sensel size should be about 2microns); today it is not very
    relevant for much larger sensors (probably not even to 3micron

    "b" was a serious factor even in 2004, when best sensors had readout
    noise of about 10 electrons. As reported, best sensors fo 2005 get
    much lower readout noise (I saw reports as low as 3 electrons); I do
    not know where this is applicable to "toy" sensors at all.


    On the other hand, there must be a significant S/N *increase* in the
    low-frequency range due to effectual decrease of bluring provided by
    the finer AAF. This increase is not effected by progress in electronics.

    Thus as electronic part of the technology improves, "a" and "b" become
    irrelevant, and a higher pixel-count sensor will *always* provide more
    information than a lower pixel-count one (of course, there is a limit:
    the Nyquist step of the cut-off frequency of the lens; practically, it
    is hard to imagine a lens for which sensels smaller than 0.7microns
    are going to be beneficial).

    But I'm sure that with toy sensors we did not reach this plateau yet.

    Hope this helps,
    Ilya Zakharevich, Dec 18, 2005
  17. Susan P

    Jasen Guest

    I have to agree with you Pete, but only if the picture quality is as good.
    Jasen, Dec 18, 2005
  18. Susan P

    Jasen Guest

    It will be worse quality when you have a very small CCD loaded with extra
    pixels. At least I think that is right?
    Jasen, Dec 18, 2005
  19. Susan P

    dj_nme Guest

    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.
    dj_nme, Dec 18, 2005
  20. Susan P

    Richard H. Guest

    Quite a discussion you've stirred up here. :)

    In short, no - 7.2MP is fine. You'll find that the resolution can be
    turned down to make smaller files, but also that memory cards and disk
    space are cheap; shooting at high-res all the time gives you greater
    flexibility later when printing.

    I've used an earlier 5MP model in this camera family, and it exceeds my
    expectations for a pocket-sized point & shoot camera. It's very simple
    to use in full-auto mode, but lots of "nerd knobs" to tweak with if you
    want to.

    As someone else touched upon... learn about the power of cropping. It
    can greatly enhance the composition during post-processing. You need
    the extra MPs so the cropped image is still high-res at large scale.
    (In fact, 300dpi @ 8x10 is precisely 7.2MP, so you may need most of that
    sensor. You could go as low as ~200dpi, but 300dpi is usually the goal.)

    Some purists may claim cropping is a crutch, you should compose
    perfectly in-camera, etc. Ignore them. In the real world, cropping has
    been a potent tool since before the digital era.

    If you haven't already, plan to spend the ~USD$70 for Photoshop Elements
    4 - it does much more than cropping; it's fairly friendly to use, but
    packed with features once you get into the details.

    Richard H., Dec 18, 2005
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