question about relationship between sensor size and print size.

Discussion in 'Digital Photography' started by ftran999, Feb 22, 2007.

  1. ftran999

    ftran999 Guest

    This is something that I'm just courious about. I understand that to
    determine what print size a digital camera (or scanned image) is capable
    of, one divides the desired dpi (e.g. 200 or 300) into the pixel dimensions
    produced by the camera. Now my question is if two cameras produce nearly
    identical resolutions but have different sensor sizes how does this affect
    print size? For example take two different DSLRs with nearly identical
    resolutions, the Nikon DX2 and the Canon 5D. If one was to determine that
    they wanted to print at 300dpi by dividing that number into the pixel
    dimensions of both cameras, you would get a print size of approx 9.5x14.5
    give or take a few fractions of an inch. Now the thing is that the Canon
    uses a full size sensor (24x36) whereas the Nikon uses a DX sensor
    (15.7x23.7). Now I'm not asking specifically about the superiority of one
    camera over the other, just happened to pick them out to use as examples,
    but THEORETICALLY if a FF camera has a sensor size that is 2.3 times the
    area of DX camera then shouldn't it be able to produce a print that is
    larger by the same factor ? Keep in mind everything will be equal, printer,
    paper, viewing distance.
     
    ftran999, Feb 22, 2007
    #1
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  2. In a nutshell, the bigger the sensor (physically speaking) the better the
    signal to noise ratio and dynamic range.
     
    Charles Schuler, Feb 22, 2007
    #2
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  3. ftran999

    ray Guest

    It doesn't.
    A pixel is a pixel. The biggest factor is going to be the compression
    involved in making the image. If they are both producing lossless images
    then the print quality will be equal - the one with the larger sensor
    should have less 'noise' at a given iso setting.
     
    ray, Feb 22, 2007
    #3
  4. ftran999

    Mark² Guest

    Not directly (since yu can print ANY size [200'x300' if you're so
    inclined...even with 1MP]...so long as quality isn't factored in), but the
    SHAPE of the sensor can make a difference to the extent that you may have to
    crop based on the print dimension ratio.
    If you shoot with a 3:2 sensor (most DSLRs), then you can print 12x18, or
    the same ratio at other sizes and take full advantage of the resolution of
    the sensor. Once you go to 8x10, or other ratio, you have to crop--throwing
    away a portion of your image.
     
    Mark², Feb 22, 2007
    #4
  5. ftran999

    erqua Guest

    Would this be more obvious in low light conditions?
    Would this be offset by the camera having a bigger lens (DSLR vs
    compact)?
     
    erqua, Feb 22, 2007
    #5
  6. ftran999

    Paul Rubin Guest

    DSLR's have bigger lenses for the precise reason that they have bigger
    sensors.
     
    Paul Rubin, Feb 22, 2007
    #6
  7. .... and because of cost or size considerations, many of the DSLR lenses
    have a smaller aperture (f/5.6) and the long end of the zoom compared to
    the f/2.8 offered by some small-sensor cameras, thus throwing away quite a
    lot of the advantage of the large sensor....

    David
     
    David J Taylor, Feb 22, 2007
    #7
  8. : This is something that I'm just courious about. I understand that to
    : determine what print size a digital camera (or scanned image) is capable
    : of, one divides the desired dpi (e.g. 200 or 300) into the pixel dimensions
    : produced by the camera. Now my question is if two cameras produce nearly
    : identical resolutions but have different sensor sizes how does this affect
    : print size? For example take two different DSLRs with nearly identical
    : resolutions, the Nikon DX2 and the Canon 5D. If one was to determine that
    : they wanted to print at 300dpi by dividing that number into the pixel
    : dimensions of both cameras, you would get a print size of approx 9.5x14.5
    : give or take a few fractions of an inch. Now the thing is that the Canon
    : uses a full size sensor (24x36) whereas the Nikon uses a DX sensor
    : (15.7x23.7). Now I'm not asking specifically about the superiority of one
    : camera over the other, just happened to pick them out to use as examples,
    : but THEORETICALLY if a FF camera has a sensor size that is 2.3 times the
    : area of DX camera then shouldn't it be able to produce a print that is
    : larger by the same factor ? Keep in mind everything will be equal, printer,
    : paper, viewing distance.

    No. Since you are not asking about the theories and limitations of the
    image capturing and storage systems, the size of the sensor is not
    directly helping or hindering the print size. If you have two sensors of
    different sizes with the same exact dimensions in pixels, each pixel will
    be representing the exact same proportion of the total image. The
    different size of the respective pixel sensing element may effect the
    ability to capture the light qualities for that single pixel, but the
    stored pixel is still representing the same portion of the finished image.

    The 300 dpi benchmark is generally a reflection of the current state of
    the art in printing technology to accurately produce a pixel on the page.
    Too high dpi, and the printing device may begin to blur the pixels due to
    the limits of ink to be deposited without difusing into the adjacent
    pixel. And too low a dpi and the individual pixels become visible. Of
    course these values are for a standard viewing distance of 3-6ft or so. If
    you plan on viewing from the length of a football field the "best" dpi
    will change. A Jumbotron image that looks nice and clear at a distance
    looks silly up close (a single color element is made up from 3 seperate
    color elements, each being about 4" square). Each "pixel" is about 8" by
    8". :) On the other hand if you can find a printer that can deposit fine
    enough "drops" of ink on a surface, and the ink does not spread into the
    next pixel, you could print an image with a very high dpi that would
    satisfy our readers who MUST examine every print with a microscope. :)

    But using 300dpi is a good benchmark, no matter what the sensors physical
    dimensions. Now if the physical size change is reflected in a change in
    pixel count, the change in size would have an effect in the print.

    Randy

    ==========
    Randy Berbaum
    Champaign, IL
     
    Randy Berbaum, Feb 22, 2007
    #8
  9. The final resolution of the camera is a chain of the resolution of
    each of several limiting factors. The larger the sensor, the less
    likely that IT is the primary limitation to resolution. i.e, a chain
    is as strong as its weakest link.

    Now, by resolution I mean the true, measured resolution based on bar
    chart or mtf tests, NOT simply the number of pixels in the sensor.
    The actual resolution of a camera is ultimately limited by the number
    of pixels, but a camera CANNOT resolve a bar frequency equal to the
    number of pixels in a given direction. That is, a 3000 pixel wide
    camera will NOT, on average, be able to resolve a chart with 3000
    lines of alternating black and white bars.
     
    Don Stauffer in Minnesota, Feb 22, 2007
    #9
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