Canon 5D vs. Medium Format (Film)

Discussion in 'Digital Photography' started by Progressiveabsolution, Sep 25, 2006.

  1. Resolution and contrast are very much the same thing. Look up MTF.

    And with modern lens coatings, the number of lens elements simply isn't a
    problem. And telephoto primes tend to have a rather small number of
    elements, e.g. the Canon 400/5.6 is 7 elements, whereas the 24-80/2.8 is 16
    elements in 13 groups, and no one complains about that lens' contrast.

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Oct 1, 2006
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  2. Yes, I do. You've missed the context of the discussion; after you've added
    seven TCs, adding the eighth doesn't capture any more detail.
    Only if the lens you started with is capable of resolving the detail. Once
    you've magnified the image from the main lens beyond reason, there isn't any
    more detail in it.
    No. The lens you started with doesn't have infinite resolution. MTF goes to
    zero at approximately 1600/(f number) due to diffraction, and lens
    abberations will make things even worse. For f/5.6, that's 285 lp/mm. You
    will not consider your dSLR image acceptable if the diffraction extinction
    point happens at Nyquist for the sensor, which is 88 lp/mm for the Canon
    400D. So 3x worth of TC on the 400/5.6 produces images that are (a)
    unacceptably soft, and (b) can't be improved by adding a TC.

    (Thanks for yelling at me here: I wasn't sure at what point one would get
    tired of adding TCs on the 300D, and you forced me to do the calculation.)

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Oct 1, 2006
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  3. Are you serious? Is that practical? For shooting landscapes I mean.

    Paul
     
    Paul Saunders, Oct 1, 2006
  4. I tend to agree with your argument in theory, but I have a skeptical
    open-minded nature and I know that theory doesn't always match fact. Edison
    was told that he couldn't send radio signals across the Atlantic, since
    radio waves travel in straight lines so they'd disappear into space. There
    was no argument, the experts were right, they knew all the facts. But he
    tried it anyway and it worked! Why? Because there was another factor that
    no-one had even considered before he tried it.

    So I'm quite happy to agree with you, in theory, but I'd like to see the
    results for myself with my own eyes before I'll really believe it.
    Life has a habit of getting in the way, doesn't it? If only we could live
    forever and waste time endlessly...

    Paul
     
    Paul Saunders, Oct 1, 2006
  5. Yes, but he's comparing photons per pixel, which is not the same thing. I
    read another web page about this f stop myth, but it's not a myth, they're
    just moving the goal posts!

    That's like saying that 400 ASA film (yeah, good old ASA, how come it's
    called ISO now?) isn't really two stops faster than 100 ASA film. Why not?
    Because of the grain! If you compensate for the grain, blah blah blah...
    Yeah, I understand what he's saying.
    Whether I need it or not, that's all I've got right now. Personally, noise
    levels are so low with the 400D at ISO 100 that I don't really understand
    what the fuss is about. Sure, 5D noise levels are undoubtedly lower, but is
    it possible to see a difference? I can't see any noise in the 18"x12" print
    I've just made, so how could I see even less? Just because it's measurable
    doesn't mean it's visible, or at least obvious.
    Yeah. Sharpness is relative too. Did you know that a 4MP image printed at
    6"x4" viewed at 20 yards is much sharper than a 17MP image printed at
    60"x40" viewed from 2 inches away? I guess that proves that a G3 is
    actually sharper than a 1DsMkII. :)

    Paul
     
    Paul Saunders, Oct 1, 2006
  6. It came as a surprise. It lightened the discussion nicely.

    Paul
     
    Paul Saunders, Oct 1, 2006
  7. That would be nice.

    Haven't they already done that for the four-thirds system?

    Paul
     
    Paul Saunders, Oct 1, 2006
  8. In this case I did, just to see what would happen. (Result in next post.)
    Of course. I never sharpen anything until the printing stage, and even
    then, I don't sharpen. Did I mention Focus Magic? Much better than USM IMO
    (and no, I'm not on a commision).
    If money were no object I'd buy it tommorow. Unfortunately it is, and even
    if I could afford it, I have other priorities. Such is life.
    I know, but the 1.8 *is* affordable for me. Surely a lens I can afford is
    more use to me than one I can't?
    I noticed that on a review I read. Much nicer bokeh, but like I said,
    beggars can't be choosers, and I don't do portrait photography anyway, so
    the bokeh is more theoretical than practical. Most of the time I'd be
    stopping it down.

    Actually the main reason I'm interested in getting some fast fixed lenses is
    for night/twilight photography, star trails, moonlit objects and so on.
    Ultra long exposures.
    Nice.

    Paul
     
    Paul Saunders, Oct 1, 2006
  9. I'll be honest, I can't see any real difference. On close inspection I
    imagined one was sharper than the other, but then another bit looked less
    sharp. At the end I honestly couldn't say definitively one way or the
    other. Slight differences in contrast in different parts of the pictures
    confused me. Perhaps I could have sharpened them more, but they looked
    pretty much identical to me.

    I did notice that the colour was different between the 300D and the 400D,
    even with the same RAW conversion settings in DPP. The 300D was more
    saturated, and with a slightly different hues, but the differences were more
    obvious on the monitor than in the prints.

    I also made an 18"x12" print from the 400D, it looks perfectly sharp to me,
    and I can't see any noise.

    Paul
     
    Paul Saunders, Oct 1, 2006
  10. Progressiveabsolution

    acl Guest

    Right, I was being sarcastic. What he is implying is of course correct,
    but "aperture" has a standard meaning and it's not the one he uses.
    No disagreement on this. The business with noise is blown completely
    out of proportion (both in terms of differences between cameras and
    absolute importance).
    And the ideal camera with respect to noise would of course be a
    single-pixel full-frame camera.
     
    acl, Oct 1, 2006
  11. Excellent! And I bet that if someone made one, some pretentious artist
    would use it and hang the results in an art gallery and critics would go to
    great lengths to explain how significant it was!

    Purity of essence? The ultimate in minimalism? The measurbator's dream
    camera?

    Paul
     
    Paul Saunders, Oct 1, 2006
  12. Progressiveabsolution

    Paul Rubin Guest

    You really want to shoot landscapes with an 800mm? Sure it's
    practical to use a telescope for that, if you want such a long focal
    length.
     
    Paul Rubin, Oct 2, 2006
  13. The noise levels at ISO 100 are the same* in pretty much all the dSLRs; the
    high-end Canons don't have enough bits in the A/D converter for ISO 100 to
    be any different.

    The fuss is about the high ISOs, where the 5D is two to four times as
    sensitive as the APS-C cameras. If you don't need that, you don't need it.
    But if you are shooting kids, sports, or doing photojournalism, it's real
    nice.

    *: The _shadow_ noise. The 5D has a higher SNR in mid-tones and higher,
    where it really doesn't make a difference.
    That's because you aren't doing any agressive burning-in of the shadows or
    single-image HDR things where you "develop" the same frame multiple times
    and recombine. It would be nice to have the extra stop or two of dynamic
    range a 16-bit A/D converter would give you. But even without it, you've got
    far better shadow rendition that film could ever dream of.

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Oct 2, 2006
  14. Progressiveabsolution

    Annika1980 Guest

    Maybe he is interested in lunar landscapes?
    Otherwise, he's gonna be doing a lot of stitching.
     
    Annika1980, Oct 2, 2006
  15. Progressiveabsolution

    Rich Guest

    The limiting resolution of a diffraction limited lens allows for
    magnification through that lens
    way beyond what you will ever see with a conventional camera set-up.
    Why do you think
    amateur astronomers use focal lengths like 50,000-200,000mm when
    shooting planets? It's not just for image scale. A lens of 100mm
    aperture can support a focal length of around
    10,000mm before it starts to "break down." If 50mm lens was
    diffraction limited (none that I know are) and had an f1.8 aperture, it
    could support (if they added no aberrations at all)
    something like 4 individual 2x teleconverters before it failed to gain
    more image detail.
    But this is all conjecture unless you do something. So for anyone
    interested, take a shot using a 200mm telephoto, then put a 2x or 3x
    teleconverter on it and take the same shot.
    Assuming no outside influences limiting resolution (like heat waves,
    etc) you will see more detail in the shot where the focal length was
    longer, but your image angle will be narrower.
    Resolution of a diffraction limited lens is dictated by aperture and
    it's proportional.

    See, here you are getting subjective and confusing sharpness with
    resolution. Unacceptably soft, what does that mean? To whom?
    If a 40" wide print looks really soft but delivers more real detail
    than a sharper looking
    20" wide print, it is still delivering more resolution, no matter how
    subjectively soft its image
    is.
     
    Rich, Oct 2, 2006
  16. Huh? What's wrong with my numbers? Lots of people stack two or more TCs, and
    find that they don't get any more detail after a certain point. The
    diffraction calculation above agrees with practical reality.
    My understanding of telescopes is that it's all about aperture, and that
    focal length can be constructed after the fact (so to speak, i.e. that it's
    the physical size of the mirror or lens that determines resolution and that
    delivering that resolution to film or sensor is a relatively separate
    issue). I've never seen an article on astronomy in Science that didn't
    verify that model. (Not that I pay more than passing attention, but I am
    curious about how the adaptive optics efforts are doing.)
    If you reread the above, you will see that "can't be improved by adding a
    TC" means exactly that; there's no more information to be had from the lens,
    so you can blow it up (i.e. enlarge the projection onto the sensor) all you
    want and you won't get any more detail because the lens is at its
    diffraction limit. Zero, nada, nil. There simply isn't infinite detail to be
    had from a 400mm f/5.6 lens. That's the reason people use larger lenses.

    You seem to be arguing that there's no limit to the resolution capabilities
    of a 400mm f/5.6 lens, and to the best of my knowledges, that's just wrong.
    That's a completely different question: you are now talking about
    presentation. I'm talking about capturing detail at the sensor. And again,
    you seem to have belief in infinite detail; lenses have hard limits at the
    difraction limit, and digital sensors have hard limits at the Nyquist
    frequency.

    My point is that the format is of minimal practical significance in getting
    all the resolution a lens is capable of into a digital file; you can project
    the center portion of the lens' FOV onto a 10MP 400D sensor, or you can
    project it onto the inner 10MP of a 5D's sensor and see pretty much the same
    20" or 40" print.

    (Next message I'll trim.)

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Oct 2, 2006
  17. Progressiveabsolution

    Scott W Guest

    Who is going to use a FL of 200m? That is like two football fields in
    length.

    Scott
     
    Scott W, Oct 2, 2006
  18. Progressiveabsolution

    Sarah Brown Guest

    Actually it was Marconi. Edison was one of the people saying it couldn't be
    done:

    http://www.ucs.mun.ca/~jcraig/marconi.html
     
    Sarah Brown, Oct 2, 2006
  19. Well that's okay then.
    No, I don't do that, so I don't need that.
    Well not on that image I didn't. There are shots where I do brighten the
    shadows a lot, but for those I generally take multiple exposures then blend
    them using layer masking or HDR.
    Indeed.

    Paul
     
    Paul Saunders, Oct 2, 2006
  20. Oops! Sorry. Thanks for the correction.

    Paul
     
    Paul Saunders, Oct 2, 2006
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