Megapixel & enlarging/croping/zooming.

Discussion in 'Digital Photography' started by Andy J, Nov 2, 2003.

  1. Andy J

    Andy J Guest

    Hi,

    First off let me apoligize if this question has been asked about 1/2
    million times. I did a few searches but can't seem to find the exact
    answer I'm looking for. Actually this is more for my wife than me.

    My wife is looking at a 4M pixel or a 5M Pixel cameras...(Not sure
    which one's yet..she seems to find a new favorite every day). Anyway,
    She had heard that with a larger mega-pixel camera, you can crop or
    enlarge an area of a picture while keeping quality. We currently have
    a 2.1 megapixel Fuji and have found this somewhat limiting. Is this
    true, false or other??

    Is there a big difference between a 4M and 5M pixel camera. I know
    better optics, etc can make a big difference, but assuming everthing
    equal.

    Any and all comments/guidance would be greatly appreciated.

    Thanks
    Andy
     
    Andy J, Nov 2, 2003
    #1
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  2. Andy J

    Trev Guest

    I presume you have already found out that the size of a print, is
    limited by the amount of pixels in your image. Cropping or throwing away
    some of your limited pixels. Means a smaller print. So the more pixels
    you have to start with. The more you can afford to crop,and still have
    enough left for a good size print
     
    Trev, Nov 2, 2003
    #2
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  3. Andy J

    gr Guest

    Well, assuming everything else equal, the choice is pretty simple. Duh!

    A 5MP image is 25% larger (in area) than a 4MP image, and 12% longer in both
    the length and width. That allows for a fair bit of cropping, but getting
    the picture framed the way you want it before you shoot it is still the best
    option.

    Some people will complain about noise in 5MP images, but I seriously doubt
    they've ever looked at real images. Dpreview does some noise tests, but IMO
    their methodology is flawed. They don't standardize to sharpness and
    contrast between models, and they don't take into account that shrinking
    larger images into smaller images results in less noise (which you can do if
    you have lots of megapixels).
     
    gr, Nov 3, 2003
    #3
  4. Andy J

    Christian Guest

    Although they have a million more pixels, 5MP cameras produce images that
    cannot really be enlarged very much more than 4MP cameras. A 5MP image is
    just over 300 pixels bigger in both dimensions so, assuming no
    interpolation and a 300dpi print, this is an extra inch in each dimension.
    Of course, you can interpolate and/or use a slightly lower output
    resolution but ultimately the difference is very small. Also, generally
    5MP cameras have the same sized imaging sensor but have an extra million
    pixels packed in there so they do tend to produce very slightly noisier
    images (less real image info and more noise means less interpolation can be
    done meaning the actual difference in enlargements is very negligible in
    practice). 5MP cameras are also more expensive...

    Having said that, if you find a 5MP camera that you like (does everything
    you want, good image quality) then I wouldn't get too hung up over any of
    this. Then again, if you find a 4MP camera that does the same (and it will
    be cheaper) then don't think you're buying "obsolete" technology. Have a
    look at dpreview.com and see the various tests and comparisons and make up
    your own mind.
     
    Christian, Nov 3, 2003
    #4
  5. Andy J

    Mark Herring Guest

    As someone already pointed out, 5Mp is only 12% more in linear
    resolution---only you can decide if that's worth it.

    The approach I recommend is to take the maximum print size and try to
    get at least 250 pixels per inch, AFTER CROPPING.

    4x6 = 1000X1500 = 1.5 Mpixels

    8x10 = 2000x2500 = 5 mpixels

    Note that digicams dont operate at either of these aspect
    ratios---Most seem to be 4:3. For example, my 2Mp Canon produces a
    1200x1600 file. At 250pix per inch, thats a 4 x 5.33 inch print

    -Mark
     
    Mark Herring, Nov 3, 2003
    #5
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