Canon 50D 5D

Discussion in 'Canon' started by Gedeon Herschberg, Sep 5, 2008.

  1. Gedeon Herschberg

    RichA Guest

    Read the caption, the image is cropped from the lens center to one
    edge, not across the field.
     
    RichA, Sep 9, 2008
    #21
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  2. Gedeon Herschberg

    Me Guest

    And it's not something you see with the 18-70 Nikkor, with several (3?)
    ED elements.
    Your "test" is a fraud.
     
    Me, Sep 9, 2008
    #22
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  3. Gedeon Herschberg

    Robert Coe Guest

    : On Mon, 8 Sep 2008 09:45:38 +0900, "David J. Littleboy" <>
    : wrote:
    : :
    : : > The full frame 5D requires either the very best film lenses you can find
    : : > to maximize performance or new lenses specifically designed for a FF
    : : > digital sensor. Nikon has some, Canon has few if any.
    : :
    : : This is a common myth. Any halfway decent lens makes lovely sharp images on
    : : the 5D. The only exception are the Canon superwides, but even the superwides
    : : make sharp images out to the corners at f/16.
    : :
    : : I wonder about the 50D, though. The 5D's Nyquist frequency is 60 lp/mm, so
    : : decent contrast in the 40 to 50 lp/mm range is required for sharp images.
    : : But the 50D's Nyquist frequency is 105 lp/mm. How many lenses have decent
    : : contrast in the 70 to 90 lp/mm range?
    :
    : I'm having trouble grasping your point, presumably because I understand the
    : underlying physics so poorly. Are you saying that with a lens of average
    : quality, aliasing will be a more serious problem on the 50D than on the 5D
    : because of the finer granularity of the 50D's sensor? And that as a result the
    : 50D requires better lenses than the 5D does? Or am I missing it altogether?

    Whereupon David responded:
    I'm still having trouble getting my head around this. As I understand (if I
    dare use that word) it, aliasing results when the resolving power of the lens
    and that of the sensor are about equal but the lines presented by the lens are
    out of phase with those detected by the sensor. And if the resolving power of
    the lens is poor, the image recorded by the sensor will be blurry, but not
    necessarily aliased. As the resolving power of the lens increases, so does the
    sharpness of the recorded image until the phase angle between the lens and the
    sensor represents twice the Nyquist frequency, at which point (absent specific
    anti-aliasing measures) aliasing effectively cancels out further increases in
    image quality. By this reasoning, the Nyquist frequency represents an upper
    bound on the advantage conveyed by a sharper lens, but doesn't imply that a
    poorer lens will perform worse than it would if the Nyquist frequency were
    lower. So rather than saying that the 50D "requires" better lenses, wouldn't
    it be more accurate to say merely that the 50D *benefits* more from a better
    lens than the 5D does?

    My knowledge of physics, such as it is, is more of an interest than a skill.
    So I'd be happy to have someone set me straight.

    Bob
     
    Robert Coe, Sep 9, 2008
    #23
  4. Gedeon Herschberg

    RichA Guest

    You brainless bumpkin, ED glass ONLY reduces effects colour error it
    has no effect on other aberrations! Moron.
     
    RichA, Sep 9, 2008
    #24
  5. Gedeon Herschberg

    Paul Furman Guest

    I believe that is a lens aberration: coma, or 'batwing' sagittal oblique
    spherical aberration (yeah I googled that). I was fiddling with a 45mm
    Nikkor (on FX) yesterday with a 14mm extension tube for closeup and saw
    something I thought was motion blur but in fact I think it was coma:
    http://edgehill.net/Misc/misc-photos/9-7-08-sushi/full-set/pg1pc2
    -click for full crop:
    http://edgehill.net/1/Misc/misc-photos/2008-09-07-sushi/full-set/crop/_0000251.jpg

    My samples are pushing the intended use of this lens pretty far and it's
    an ancient lens design. The 58mm f/1.2 noct was specially designed to
    overcome this issue and it costs a ridiculous price these days
    (discontinued). But yeah, I think Nikkors tend to have this issue:
    something in their designs that optimizes sharpness at normal apertures
    at the cost of these sorts of aberrations.

    And, yeah there is a big difference in Rich's comparison, being at the
    edge of the zoom's range and same focal length with a different crop
    factor (the Nikkor is magnified): surely 17mm & 18mm are not comparable?

    Here's an example of motion blur with a very similar shape:
    http://edgehill.net/Misc/misc-photos/9-7-08-sushi/full-set/pg1pc1
    -click for full crop:
    http://edgehill.net/1/Misc/misc-photos/2008-09-07-sushi/full-set/crop/_0000250.jpg

    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, Sep 9, 2008
    #25
  6. Gedeon Herschberg

    Me Guest

    My apologies. Aspherical elements reduce such aberrations.
    There's colour aberrations as well as coma spherical aberration in your
    sample shot. That's _not_ typical of the Nikkor 17-80. That lens has a
    few faults for sure, but not those faults.
    In any case, it's nuts comparing two wide zooms designed for different
    systems when comparing one at the extreme wide end, the other toward
    middle of the range. Are you nuts?
     
    Me, Sep 9, 2008
    #26
  7. If. Depends on the lenses. A consumer 70-300mm at 30mm is a
    different beast than an L prime lens.
    - All the other features the 50D has which the 40D has not.
    - Using your glass to the max. (Many people have many times
    the body price in lenses.)
    Nope, unless you compare different enlargements. It'll get the
    maximum out of your lens. If your lens can't deliver, you have
    wasted space (for the extra MPix that don't carry information)
    but not quality.

    Though the 50D *might* have increased noise (or noise supression)
    at high ISO. If so and how much remains to be seen; ist also
    depends on if you actually use high ISO settings. That's the
    only real thing In can think of that may reduce image quality.

    -Wolfgang
     
    Wolfgang Weisselberg, Sep 9, 2008
    #27
  8. Gedeon Herschberg

    Eric Stevens Guest

    I did read it. My comments still stand, unless the image is taken from
    a small segment a long way from the centre.



    Eric Stevens
     
    Eric Stevens, Sep 9, 2008
    #28
  9. Gedeon Herschberg

    Eric Stevens Guest

    But why does it appear to be constant in magnitude and direction
    across the image?



    Eric Stevens
     
    Eric Stevens, Sep 9, 2008
    #29
  10. Gedeon Herschberg

    Paul Furman Guest

    It is an edge crop.

    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, Sep 9, 2008
    #30
  11. Gedeon Herschberg

    Paul Furman Guest

    Because it's an edge crop. The right side doesn't show as much.

    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, Sep 9, 2008
    #31
  12. And at *least* 2440 pixel in that dimension, so you can
    /resolve/ 1220 line pairs. That means 9Mpix is enough.

    [...]
    That's basically a fancy way of saying "when the sensor is smaller
    (as in APS, or worse, compact cameras), you've got to enlarge
    more for the same final result. Enlarging more also enlarges
    any lens problems and limitations." :)

    However, I understood the problem as "you have a sensor with
    15MPix(!), which lens will give enough information so you have
    an advantage over, 8, 10, 12 MPix?"
    s/21/82/

    However, the 5D needs the 51 lp/mm even in the corner of the
    EF lens for full quality, whereas the 50D doesn't exploit the
    (usually weaker) outmost part of the image circle of an EF lens.
    Thus _just_ comparing the lp/mm can be misleading.

    -Wolfgang
     
    Wolfgang Weisselberg, Sep 13, 2008
    #32
  13. I stand corrected.
    True.
    At least from the (sensible) 'same field of view' point of view.

    It can be different from a 'same lens' POV --- at least dpreview
    says that that the Nikon AF-S VR 70-200mm F2.8 G ED has quite a
    different performance on FX than on DX.
    That may be the odd one out, but I still think Nikon tweaked
    it for maximum DX performance.

    -Wolfgang
     
    Wolfgang Weisselberg, Sep 14, 2008
    #33
  14. What a wonderful sounding discussion for physic nurds and totally
    unhelpful for us plebeians.

    Now here is a question which if answered would help me:
    How would the pictures compare taken with -
    Canon 5D fitted with a Tamron 28-300 and
    Canon 50D fitted with a Canon 18-200 (and or Tamron 18-250)
    in daylight and in
    low light at 1600 ISO each?

    So we compare EF-s lenses and a non EF-s lens on both cameras and test
    higher ISO shooting even at 3200 if the 5D has that capability.

    If still interested add the "cheaper" L lenses such as f4 17-40 on the
    cameras.

    The answers witout the "why"s i.e. no technical terms would be revealing.

    Regards,
    Gedeon
     
    Gedeon Herschberg, Sep 19, 2008
    #34
  15. Gedeon Herschberg

    OldBoy Guest

    Both Tamron lenses are very, very, very mediocre.
    I wouldn't insult the camera makers of any brand by usesing them.
     
    OldBoy, Sep 19, 2008
    #35
  16. Let me put it this way: you got a 50.000 horse power engine ---
    and all you can think about is putting it in a econobox using
    wheels rated for at most 45 miles/hour?

    Use good lenses. Always use good lenses. The body can only
    record what the lens can deliver. With superzooms you don't
    need much of a sensor.

    If you *really* need a 28-300, use the EF28-300mm f/3.5-5.6L
    IS USM. It's not great in any way, but it certainly is
    better than the Tamron.

    -Wolfgang
     
    Wolfgang Weisselberg, Sep 19, 2008
    #36
  17. The later Tamron is so much superior to the earlier that you should at
    least drop one of those three "very"s when describing it. It's a new
    generation with a new standard of performance in that range.
    Fair enough. You clearly have very high standards of lens
    performance. But you do seem to be implying that you might
    nevertheless be prepared to use the Canon 18-200 zoom, despite it
    sharing the inevitable performance deficits of even the most recent
    and highest quality zooms of such a range. Can you clarify?
     
    Chris Malcolm, Sep 19, 2008
    #37
  18. Gedeon Herschberg

    OldBoy Guest

    Okay, dropping one :)
    I have a EOS 5D & 40D with
    EF 24-105 f/4 L IS USM
    EF 70-200m f/4 IS USM
    EF 100 f/2,8 USM macro.

    I can't imagine me buying the EF-S 18-200 unless Canon found a magic way.
    Even then ......
     
    OldBoy, Sep 19, 2008
    #38
  19. I can not afford that sort of budget. What about the present 5D (digic
    II) compared top the new 50D. Same price for 50D plus lens as 5D body
    only and I have lenses for it.
    Regards,
    Gedeon
     
    Gedeon Herschberg, Sep 21, 2008
    #39
  20. Gedeon Herschberg

    Robert Coe Guest

    : What a wonderful sounding discussion for physic nurds and totally
    : unhelpful for us plebeians.
    :
    : Now here is a question which if answered would help me:
    : How would the pictures compare taken with -
    : Canon 5D fitted with a Tamron 28-300 and
    : Canon 50D fitted with a Canon 18-200 (and or Tamron 18-250)
    : in daylight and in
    : low light at 1600 ISO each?
    :
    : So we compare EF-s lenses and a non EF-s lens on both cameras and test
    : higher ISO shooting even at 3200 if the 5D has that capability.
    :
    : If still interested add the "cheaper" L lenses such as f4 17-40 on the
    : cameras.
    :
    : The answers witout the "why"s i.e. no technical terms would be revealing.

    You've already gotten two responses strongly disparaging the Tamrons, one
    explicitly and the other in a blanket denunciation of any non-Canon lens. But
    I can't help noticing that neither responder acknowledged ever having seen,
    much less used, either of those lenses. ;^)

    Bob
     
    Robert Coe, Sep 21, 2008
    #40
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