D100 and Rebel WTF??? 6MP vs 3MP Opinions please....

Discussion in 'Digital Cameras' started by The Dude, Jan 6, 2004.

  1. The Dude

    The Dude Guest

    I suppose the slate tiles on the tower bridge roofs are aliasing too? Many
    aspects of the SD9 image do show more detail than the D60. Call it aliasing
    if you like.
    The Dude, Jan 7, 2004
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  2. The Dude

    Chris Brown Guest

    If you're referring to the tiles on the centre spire, ISTM that neither
    camera resolves them particularly clearly. The SD9 image does have lots of
    faint thin horizontal lines on it if you look closely, which I assume is
    what you're refering to, but I'm inconvinced those are actually the edges of
    tiles - the tiles themselves look to be rather larger slabs, so whilst this
    particular example shows *something*, I don't think it shows anything
    conclusive. Other areas of the image, such as the gibs on the red cranes,
    give a slight edge to the D60.
    I have performed the suggested experiment, and posted my results earlier in
    the thread. The comparison image (10D) is here:


    The image was imported in Adobe Camera RAW iwth no sharpening. The bottom
    one was resized to 3 megapixels, and then back to 6 megapixels with bicubic
    interpolation. Both then had the same level of sharpening applied.

    Even without blowing the image up to examine the individual pixels, it's
    brutally apparent that the original premise of the thread does not hold for
    this image. The 3 megapixel image looks quiute a lot softer than the 6
    megapixel image.
    Chris Brown, Jan 7, 2004
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  3. The Dude

    Chris Brown Guest

    It's not that it's "less than perfect", it's just plain wrong. The fence
    almost certainly doesn't look like that in real life.
    Well, I do find the irregular gaps and thick lines to be less visually
    pleasing than the softened haze of the D60 image. Bear in mind that the same
    aliasing process that produced these irrecular lines would, when
    photographing something with regular horizontal *and* vertical detail,
    produce moire. Few people find that they prefer images with moire patterns
    in to similar ones without.

    Anyway, this comparsion does not support the premise of the thread - the
    differences we are seeing here are attributable to aliasing and different
    amounts of sharpening between the two images. I performed the experiment
    outlined at the start of the thread, and instead of finding that there was
    no significant visual difference, as claimed, I discovered that the resized
    image ran out of detail significantly before the unresized image. Judge for

    Chris Brown, Jan 7, 2004
  4. "The Dude" <.> wrote in message
    6MP. > I then zoomed into the top of the left tower on each image
    (@300%). No
    Perhaps if you use a better focused version from a D60, you can?
    Try this one (4626 KB):

    This shows that focus errors can make these comparisons a bit awkward.
    Also notice the (slight) difference in magnification between the Sigma
    and Canon images. Also look for stair stepped diagonals.

    Bart van der Wolf, Jan 7, 2004
  5. You're comparing 3 MP from a camera with no anti-aliasing filter to 3
    MP from a camera that does have an AA filter. That's the main
    difference between the two images. This simply doesn't show the effect
    that you claim it does (the difference between 3 MP and 6 MP output
    from the same camera.)

    Dave Martindale, Jan 7, 2004
  6. Yes, honestly. I'd buy the camera on the right even if it cost more.

    Consider that when you print the whole frame at any reasonable
    size, you are going to be able to see little or no detail in that area
    anyway. While if you *do* care about resolving the detail in the
    riverboat, you'll use a longer lens. So the "blurry" 6 MP image isn't
    really unsharp. (My highest res camera is a 4 MP Bayer type; I'd love
    to have the 6 MP 300D or 10D instead).

    Basically, the Canon image either shows what was really there, or it
    shows a blur. The SD9 image always shows something that looks sharp,
    but may not be quite what was really there. I couldn't trust it to do
    something predictably faithful to the original scene, even if what it
    produces often looks quite good. And a lot of the difference between
    the two is in sharpening, which I'd rather do myself anyway.

    Dave Martindale, Jan 7, 2004
  7. The Dude

    The Dude Guest

    Better. The tiles are indeed equally resolved in this image.
    Magnification? Well, both were shot through Sigma 50 mm F2.8 EX. Jufdging
    by the parrallax of the railing, the vantage point is clearly a bit shifted,
    but not significantly with respect to the bridge. Distance looks to be
    about identical. The other link you sent makes the comparison closer
    indeed. Still, pretty damn close for 3MB vs 6MB, no?
    Yes. The Foveon in the Sigma has clearly lost some of the highlights where
    the Canon hasn't, too -- despite resolving less shadow detail.
    The Dude, Jan 7, 2004
  8. The Dude

    The Dude Guest

    Agreed. But that does include the well documented advantages of RAW image
    processing. My discussion has only included the, admittedly, compromised
    jpeg output of the cameras. Can you RAW process to a 3MP tiff? That might
    be closer.
    The Dude, Jan 7, 2004
  9. Don't overlook that the sensors have a physically different size.
    Calculated from the sensel pitch, the Canon D60/10D sensor measures
    22.6568x15.113 mm, and
    the Sigma SD-9/-10 sensor measures 20.68416x13.78944 mm.
    So, even with equal Field of View, the Canon sensor is more than 9.5%
    larger in both dimensions and thus requires less enlargement for equal
    sized output.
    Yes, pretty good. However, the lack of AA filter and small fill factor
    of the SD-9's sensor unfortunately introduces more artifacts than I
    can tolerate (YMMV). Out-of-focus areas e.g. look very strange, just
    look at some of the Sigma close-ups others have provided. Single hairs
    show as two-three parallel ones, very distracting.

    Bart van der Wolf, Jan 7, 2004
  10. The Dude

    Chris Brown Guest

    Yes, although I'm pretty sure that all it (Adobe Camera RAW) does is produce
    the 6 megapixel image and then interpolate it down, so it's unclear why
    there'd be any difference.
    Chris Brown, Jan 8, 2004
  11. The Dude

    The Dude Guest

    No. I'm comparing 3MP without AA to a *6MP* with AA. As for the
    difference from the same camera, try it yourself and decide. I did.
    The Dude, Jan 8, 2004
  12. You're right. That was a typo. But the point remains: you're mainly
    looking at the effect of removing the AA filter, not of 3 vs 6 MP.

    Dave Martindale, Jan 8, 2004
  13. The Dude

    Chris Brown Guest

    All else being equal, the linear increase in resolution from 3 megapixels to
    6 megapixels is 40%. The difference will be a bit less in this case, because
    the SD9 lacks an antialias filter, which will give a slight resolution
    increase at the expense of artifacting. IOW, we're looking at a difference
    is actual resolving power of somewhere in the region of (sticks finger in
    air) 30ish percent. It's not that surprising that the images look similar.
    Maintaining detail and colour fidelity as the image approaches blowout is
    one area where the Canon sensors excel, and the Foveon sensor needs some
    Chris Brown, Jan 8, 2004
  14. SNIP
    Imagine what would happen if the next Canon DSLR, say an 8MP EOS-3D
    (!) had a user removable AA filter...
    Besides a dust and aliasing issue, it would kill Foveon, and spark a
    whole new discussion ... ;-)

    Bart van der Wolf, Jan 8, 2004
  15. The Dude

    The Dude Guest

    Heheh... careful with the "kill Foveon" stuff. Might get nippy in here:)
    The Dude, Jan 8, 2004
  16. So who wants to compare two cameras that produce bad images? It would
    not be an improvement if you removed the AA filter from the Bayer

    Dave Martindale, Jan 8, 2004
  17. The Dude

    Mike Engles Guest

    If you go to Luminous-Landscape.com, there are reviews of digital backs
    for medium format cameras. The USP seems to be that these backs do not
    have AA filters. Admittedly these backs have very resolution, but the
    pixel density must be similar to smaller sensors.

    The reviews and the results are excellent.

    Mike Engles
    Mike Engles, Jan 8, 2004
  18. That's a somewhat different situation, for two reasons.

    First, medium format lenses tend to have lower resolution per mm than 35
    mm camera lenses. The format is much larger, so the total usable
    resolution in line pairs per picture height is larger for medium format,
    but the line pairs per mm is lower. So the lens blur spot is larger for
    medium format, and if the blur spot gets sufficiently large (1-2 pixels
    in diameter) it provides all the low-pass filtering needed. (This may be
    Kodak's rationale for leaving the filter out of the Kodak 14n, too,
    since its pixel density is high).

    Second, some of these backs are scanning backs that acquire 3 colour
    samples per pixel (using well-separated colour responses, so this isn't
    equivalent to Foveon sensors, in case George is reading). Even if such
    sensors suffer some spatial aliasing, they don't have any luma/colour
    crosstalk problems, so the images may be more tolerable even with some

    A Bayer sensor suffers misinterpretation of high-frequency monochrome
    detail as colour, if the detail is the right frequency. Thus, the
    antialiasing filter is particularly important for a Bayer sensor.

    Dave Martindale, Jan 9, 2004
  19. George Preddy, Jan 10, 2004
  20. The Dude

    Mike Engles Guest


    Certainly in a different class.
    Superb! These Sigma cameras, do have their problems, but they are also
    capable of stunning images. Sigma must perservere and correct the
    problems, if they are correctable.

    Mike Engles
    Mike Engles, Jan 11, 2004
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