Does your lens have better resolution than the sensor?

Discussion in 'Digital Photography' started by per, Feb 3, 2004.

  1. per

    per Guest

    Hi,
    The most expensive digital camera setup seen, the Hubble high resolution
    camera, has got a one megapixel (1024*1024) sensor.
    Goes a long way to say that optics are more important than megapixels, doesn
    't it?
    Now, back on earth, have you seen tests that clearly states that the lens
    has the same, or better, resolution as the sensor, on any, consumer or pro,
    digital pocket or slr camera?
    /per
     
    per, Feb 3, 2004
    #1
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  2. Hold on there partner. I believe that Hubble sensor creates many images
    that are stitched together so it is in fact a multi-megapixel image. No
    consumer camera that I know of is designed to do this with anything close to
    the degree of accuracy of the Hubble.
     
    Joseph Meehan, Feb 3, 2004
    #2
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  3. per

    KBob Guest

    I definitely find that many lenses (even Nikkors) fail to adequately
    resolve to the capability of even the D100 (6.1 Mpx). This is
    particularly true with the zooms that go beyond 2:1 and extreme WA
    types. The problem of lens resolution is considerably greater with
    the Kodak 14n, and to fully exploit its capabilities I need to be
    careful about lens choice and taking advantage of the best F/# range
    for each. Others have also observed that digital cameras seem to be
    more prone to reveal lens problems than does film.

    Just to consider the 14n, its resolution has been measured at about
    2500-2800 lines/image height, or about 80 l/mm. Reviewing a series of
    prime lens tests I did a while back, there were many well-honored 35mm
    lenses that failed to resolve at this level, even when measured under
    the most favorable conditions. Admittedly there were a few Summicrons
    and Nikkors that could resolve at over 3 times this value at their
    best settings, but this could only be demonstrated by use of special
    spectroscopic or HC film. Interestingly, medium-format lenses such as
    used with Hassleblad and Bronica were generally poor resolvers
    compared to the best 35mm types, and the larger format lenses were
    much worse still. Today's modern crop of "computer-designed" lenses
    haven't demonstrated any great improvement in resolution, although
    contrast has been improved. Nearly all the modern zoom lenses I've
    tested are found to be terrible resolvers through a large portion of
    their ranges, except for the very limited ones. For the 14n I will
    often favor prime lenses in order to show the camera's best capability
    if large prints are to be made. Several well thought-of lenses are
    only marginally acceptable with the D100, and unacceptable for
    critical use with the 14n.
     
    KBob, Feb 4, 2004
    #3
  4. per

    Pete Guest

    Great question.

    After some 10,000 pics on an 8X zoom digital, I've come to the conclusion
    that the lens quality is really poor in the upper half of the zoom range.
    It's so bad that at 8X and 1/60th sec, you can't even see handshake! The
    results are marginally helpful for e.g. IDing birds at a great distance,
    but I'd never call them printable pictures. Lens resolution *way* less than
    sensor resolution.

    I haven't proven this yet, but I suspect you'd get better pics by using a
    high-quality 3X zoom and cropping to 8X on the puter.

    Peter
     
    Pete, Feb 4, 2004
    #4
  5. per

    jriegle Guest

    A couple points here...

    The 6mp cameras have more sensors per mm than the full frame, higher mp ones
    due to their smaller sensors. For example, the D10 or Rebel has 6mp packed
    on a APS sized sensor. If the size and distance between elements were the
    same and covered the whole area of a 36x24mm 35mm frame, it would equale
    about a 15mp camera. This means the 10D or Rebel requires more resolving
    power from the lens then 11mp or 14mp full frame cameras. An interesting
    side note to this is that our standard SLR lenses would be unnaceptible in
    terms of resoving power if they could be mounted on the compact digitals due
    to the very fine pitch of the sensor elements on those tiny chips.

    I find that my Canon lenses can out resolve my dRebel (except in the corners
    of the image at some apertures). I'm sure the same is true for Nikon.
    However, other optical properties (inadequacies) of the lens seem to be
    brought forth with the digital more than with film. See my test:
    http://home.att.net/~jriegle/ltest.htm

    Not quite. More like 40 because for every black line there is a white space.
    This is called a cycle or a line pair. No way can this camera resolve 80
    l/mm. The sensor resolution alone (not even considering the filters and
    algorithms) are not high enough for that! Consider the sensor is 36x24mm in
    size and the resolution is 4536x3024. Using the horizontal numbers
    4536/36=126 pixels per mm. or 63 line pairs per mm (considering one strip of
    pixels sees the black line and the adjacent strip sees the white and so on).
    Since Bayer sensors have blending filters and algorithms, your left with
    much less resolving power 30-45 linepairs at best.
     
    jriegle, Feb 4, 2004
    #5
  6. The best quality single focal length lenses can resolve 80-120 lpmm.
    The effective resolution on film is in the range of 40-65 lpmm under
    the usual camera use conditions. Many zooms are worse, of course.
    So for the time being a good camera lens with fine grain film beats
    a digital setup. In many cases digital camera makers blur the images
    slightly to eliminate moire.
    Expect the balance to shift over the next few years..
     
    Robert Feinman, Feb 4, 2004
    #6
  7. per

    Don Stauffer Guest

    Early digicams (so-called VGA, or 640 x 480 pixels) generally had a lens
    clearly superior to that needed for that much resolution. However,
    today as we are getting 3-6 Mp cameras, the lens in most cameras is
    about the same blur circle capability as the pixel size. That is, today
     
    Don Stauffer, Feb 4, 2004
    #7
  8. per

    YoYo Guest

    Did the lenses have any filters on them? uv, haze, skylight??
     
    YoYo, Feb 4, 2004
    #8
  9. per

    KBob Guest

    Yes...but whoever said that the Kodak sensors mentioned use blending
    filters? They don't.
     
    KBob, Feb 4, 2004
    #9
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