The Joy of Pixel Density

Discussion in 'Digital Photography' started by John P Sheehy, Jul 15, 2008.

  1. I've made a direct comparison of RAW data per unit of area in the deep
    shadows of ISO 100 between the FZ50 (1.97 micron) and the 400D (5.7
    micron). Exposure is the same, same Av (f/4.5), same Tv (1/100), same real
    focal length (22mm), both shot at "ISO 100" pushed to ISO 13,500. Large
    crop is 100% for FZ50 (0.4MP), and small crop is 100% for 400D (0.05MP),
    and the other two are the other camera scaled to the 100% crop of each. As
    I already knew, the bigger pixels of the DSLR are inferior compared to the
    higher pixel density of the small sensor camera:

    http://www.pbase.com/jps_photo/image/100092629
     
    John P Sheehy, Jul 15, 2008
    #1
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  2. John P Sheehy

    Roy G Guest


    I am glad you are happy with the results of your testing.

    Please continue to enjoy the results from your FZ50.

    I hope you don't mind if I still prefer the quality I get from my Nikon
    D300.

    Roy G
     
    Roy G, Jul 15, 2008
    #2
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  3. John P Sheehy

    Dev/Null Guest

    Another Measurebator!
     
    Dev/Null, Jul 15, 2008
    #3
  4. John P Sheehy

    Paul Furman Guest

    Of course, the DSLR image is enlarged more than 3x!

    7.18 x 5.32 mm
    24 x 18 mm

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

    all google groups messages filtered due to spam
     
    Paul Furman, Jul 15, 2008
    #4
  5. John P Sheehy

    Jufí Guest

    I suggest you call the NY Times or Scientific American since your expirement
    completely contradicts what every tester has shown to date. Do you think
    there might be a problem with your methodology? How about just shooting the
    same scene, same angle of view, and enlarging each image to 100%? Too
    complicated?

    Sorry, but larger pixels always win the day.
     
    Jufí, Jul 15, 2008
    #5
  6. John P Sheehy

    Scott W Guest

    The test is interesting but some thought is needed to interpret what
    it means. If you had a really good lens on the DSLR and had 1.97
    micron pixels across the same size sensor area then you might get
    improved results over the larger pixels. This would require a pretty
    good lens however, past what most lenses 35mm lenses will produce.

    Given the limits of the current lenses we start to get to diminishing
    returns for more pixels on the same size sensor. It seems that going
    much below 4-5 microns for the current 35mm lenses does not make a lot
    of sense.

    Of course there is nothing to stop someone for designing a large
    sensor with 2 micron pixels and designing a new set of lenses to go
    with it, but the cost of a lens starts to go up fast as it is required
    to resolve smaller pixels. IN the case of the FZ50, its lens covers
    a much smaller image circle then the 400D, so you could not simple use
    this lens on a larger sensor camera.

    If we are just looking at whether small pixels or large pixels are
    better, given a fixed number of them, then the test photos should
    really cover the same field of view rather then having the same FL.

    My conclusion is that there is a potential for improved images with
    more pixels, but to realize this potential we need better lenses.

    Scott


    The test is interesting but some thought is needed to interpert what
    it means.
     
    Scott W, Jul 15, 2008
    #6
  7. John P Sheehy

    Paul Furman Guest

    I was figuring roughly 3x the linear sensor size... in AREA it looks
    like this:
    http://www.dpreview.com/reviews/com...eras=panasonic_dmcfz50,canon_eos400d&show=all
    Sensor size
    1/1.8 " (7.18 x 5.32 mm, 0.38 cm²) 22.2 x 14.8 mm (3.28 cm²)
    Pixel density 26 MP/cm² 3.1 MP/cm²

    ..38 / 3.28 = 8.6 times more surface area
    at the same density, an AP-S sensor would have
    (3.28 cm²) x (26 MP/cm²) = 80 megapixels

    --------------
    80 megapixels !
    --------------

    Or the other way around
    (0.38 cm²) x (3.1 MP/cm²) = 1.2 megapixels


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

    all google groups messages filtered due to spam
     
    Paul Furman, Jul 15, 2008
    #7
  8. John P Sheehy

    John Sheehy Guest

    Thank you for making sure you fully understood what was going on before
    commenting! You can go back to sleep now!


    --
     
    John Sheehy, Jul 15, 2008
    #8
  9. John P Sheehy

    John Sheehy Guest

    Of course, but 2.89x, not 3x+. That's the point, or at least part of it.

    --
     
    John Sheehy, Jul 15, 2008
    #9
  10. John P Sheehy

    John Sheehy Guest

    What were they testing, *exactly*? Did they have access to the RAW data,
    or just JPEGs and conversions?
    Not at all; this is as close to "all other things being equal" as we can
    expect to get, for comparing the IQ effects of pixel density in light-
    starved situations. In all probability, the lens on the 400D has nowhere
    near the MTF of the lens in the FZ50, but even a B&W checkerboard pattern
    with 1-pixel tiles would be relatively soft blown up 289%.
    No; too *irrelevant* to the issue of PIXEL DENSITY.
    Sorry, but that's wrong. With a few exceptional situations (specifically
    read noise, but not shot noise, at ISOs 1600 and above, in a very small
    number of DSLRs), smaller pixels filling the same sensor area give better
    imaging. Larger pixels are only universally better when they are doing
    the same job; IOW, when they have the same imaging responsibility.

    --
     
    John Sheehy, Jul 15, 2008
    #10
  11. John P Sheehy

    Roy G Guest

    YAWN !!!!
     
    Roy G, Jul 15, 2008
    #11
  12. John P Sheehy

    Scott W Guest

    What has been shown is that for the same number of pixels larger
    pixels win. What has not been shown, at least I have not seen it, is
    that for the same sensor area larger pixels win, in fact for many
    cases they clearly do not.

    Take a FF sensor, 10 MP pixels will win over 1 MP, even though the 1
    MP sesnor will have larger pixels. At some point however fewer pixels
    will win, for example 100 MP will win on a FF sesnor over 1000 MP, by
    the time the pixels are down to the size needed to fit 100 MP there
    will be little gain in going smaller.

    So somewhere there is the sweat spot, the 1Ds III has I believe 21MP,
    I doubt this will be the max number we see. BTW Most people would
    prefer the 21MP on the 1Ds III vs. the 11 MP on the 1Ds

    Scott
     
    Scott W, Jul 16, 2008
    #12
  13. John P Sheehy

    Scott W Guest

    If 35mm lenses had the resolution then 80 MP would be well worth
    having for some photos, but for a FF sensor 20-30 MP is likely to be
    the useful limit, time will tell.

    Scott
     
    Scott W, Jul 16, 2008
    #13
  14. John P Sheehy

    Jufí Guest

    John, nothing you've posted here is correct. If you want, I'll shoot pix
    using my G9 and 5D at ISO 1600, and post the 100% crops. Resolution of the
    sensors is very close, only the size of the pixels is very different. It
    will shot that smaller pixels simply cannot compete with larger pixels.
    Unless I'm totally missing your point here...
     
    Jufí, Jul 16, 2008
    #14
  15. John P Sheehy

    Scott W Guest

    The point he is making, with some trouble, is that for the same size
    sensor more pixels are better, which is often, but not always, true.

    Scott
     
    Scott W, Jul 16, 2008
    #15
  16. John P Sheehy

    Scott W Guest

    Do we really need more cross posting?

    Scott
     
    Scott W, Jul 16, 2008
    #16
  17. John P Sheehy

    John Sheehy Guest

    The Canon 180mm Macro, the Tamron 90mm macro, the Canon super-teles, and
    many other lenses are fully capable of using 200MP FF, now. Even for
    lenses that are more than marginally oversampled at 2 microns, the gains in
    DR and lower read noise at low ISOs is worthwhile. You just are going to
    need a lot more storage space, and give up the 11fps burst, at least at the
    beginning.


    --
     
    John Sheehy, Jul 16, 2008
    #17
  18. John P Sheehy

    John Sheehy Guest

    I've used lenses I own on 8 and 10 MP APS DSLRs with stacks of TCs of 2.8x,
    and 4x, and gotten detail that was fragile enough to get lost downsampling
    to 70%. This means that these lenses should enjoy 8x to 16x the pixel
    density, without the TCs.

    --
     
    John Sheehy, Jul 16, 2008
    #18
  19. John P Sheehy

    Paul Furman Guest

    That's just AP-S. Full frame looks like this:
    24x36mm = (8.64 cm²) x (26 MP/cm²) = 225 mexapixels

    That is quite some difference.

    Olympus 4/3 sensor works out to 63 MP.

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

    all google groups messages filtered due to spam
     
    Paul Furman, Jul 16, 2008
    #19
  20. John P Sheehy

    John Sheehy Guest

    Then the 400D would clearly be better, noise-wise, with about 60% the read
    noise of the FZ50, and about 4x as many photons collected. Optically, the
    comparison would depend on what lens was on the 400D.

    Of course, such a test would give a result already expected by almost
    anyone who knows anything at all about digital imaging, but would tell us
    absolutely nothing about the effects of pixel *density*; only about sensor
    size.

    --
     
    John Sheehy, Jul 16, 2008
    #20
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