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The Circle of Confusion, 'Do Sensors "Outresolve" Lenses?' and Our Digital Demands

Discussion in 'Open Gear Talk' started by BBW, Sep 16, 2010.

  1. BBW

    BBW Administrator Emeritus

    Jul 7, 2010
    betwixt and between
    At José's request, I've started this thread as a jumping off place for continued discussions regarding a link that Marcus posted over on his thread: https://www.photographerslounge.org...e-digital-camera-built-film-ones-existed-411/ in which he referred to an article, dated June 2008, that has been published in Luminous Landscapes: "Do Sensors "Outresolve" Lenses?, written by Rubén Osuna and Effrain Garcia.

    Here is the introduction from the linked article, to whet your appetites:
    Now we have a thread devoted to this article as a reference. Enjoy the article, and the continued cogitating!
  2. Brian

    Brian Top Veteran

    Jul 7, 2010
    Most digital cameras use Mosaic filters, "Bayer Filters" being the most popular, for color. Most cameras use anti-aliasing filters which basically "blur" the image slightly to get rid of color aliasing due to these filters.

    A camera with a 5micron pixel size "would" resolve 100lines/mm if it were monochrome, but is probably closer to 50lines/mm with the anti-aliasing filter. I have a 1953 Jupiter-3 that can match that resolution. And at F4, does much better.

    The M8 does not use an AA filter. Uses 6.8micron detectors. That is 72lp/mm, and aliasing can creep in. The lens is out-resolving the Mosaic Filter's 36lp/mm.
  3. Here's a real-world example (Lumix G2, 1/50sec ISO100, Panasonic/Leica 45mm macro open to f/2.8)
    Cropped and exported to jpg, no other post.

    In this case, I suspect the lens outperforms the sensor, in traditional terms. Both the sharp highlight detail in the foreground and the soft bokeh in the background (it's a nice lens :)  get lost in the sensor's noise.

    Of course, after I try to read the post a few more times, I may find that this reply comment is not related . . . :/
    • Like Like x 2
  4. Brian

    Brian Top Veteran

    Jul 7, 2010
    Full image scales to 1024p across, Leica M8, ZK Sonnar 5cm F1.5:


    Tight crop, full-res: 1949 ZK 5cm F1.5 Sonnar at F4:


    The color artifacts are introduced because the detail is more highly resolved than the Bayer pattern mosain filter. The M8 does not use an AA filter.
    • Like Like x 2
  5. But if you look at the smooth surfaces, there's absolutely no noise. Very different from my noisy G2.
    • Like Like x 1
  6. Brian

    Brian Top Veteran

    Jul 7, 2010
    I am quite happy with the image quality from the M8. I shoot ISO 160 when possible, but have used it at 2500 without problems.

    My EP2: I use at ISO 200 whenever possible. I have not noticed a noise issue.
  7. MarcusGR

    MarcusGR Rookie

    Sep 11, 2010
    Thank you both, Arpoador and Brian, for providing examples of lenses out-performing sensors (even though, on my screen, I am not able to see that much noise in the G2 photo either: it would be nice to see the same image taken by both cameras, with the same ISO setting, by some rich fellow ... :)  ; by the way: you both omitted to "declare" the ISO setting you adopted for those photos ....; was it 160 for Brian's ? and what for Arpoador' s ? ). Hard time for those unlucky sensors, though, both having to deal with Leica lenses....
    But what would you expect to see when the opposite were true ? I mean, if a sensor out-performed an objective ? Would there be any tell-tale symptoms, or the resulting image would just look "out of focus" ? Based on Osuna&Garcia conclusions, I suspect some camera might already have been driven into the desert by the pixel race, even though - of course - it would be stupid to put a good (= costly) sensor and processor behind a poor lens ... (by the way:extra-pixels may be used to improve the image anyway, as it seems; see http://www.luminous-landscape.com/essays/not-so-fast.shtml ).
  8. Hi Marcus -

    The ISO is 100 on the G2 pic. Thanks for calling that out. I added the ISO & time to the pic info.

  9. Brian

    Brian Top Veteran

    Jul 7, 2010

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