Pixel question . . .

Discussion in '35mm Cameras' started by Eric Miller, Aug 27, 2008.

  1. Eric Miller

    Eric Miller Guest

    Aside from marketing decisions is there any good reason that camera
    makers would shy away from using their better technology to increase the
    light-gathering ability of a pixel without making it smaller?

    For example: Canon claims that the 50D has better light gathering
    ability with smaller pixels due to better microlenses and other stuff I
    don't really understand very well. So why not use better microlenses to
    improve the light gathering ability of the 5D, for example, instead of
    adding more pixels? Wouldn't such an application of their new technology
    allow for a camera that takes noise free images at 1600 ISO? (Granted,
    1600 ISO images are pretty good on the 5D as is, but why not make it

    Again, I understand the megapixel race from the marketing standpoint and
    why that precludes this, so no need to address that issue.

    Another question: If the "full well" issue effectively prevents a lower
    ISO than than somewhere around 100, won't that issue effectly mandate an
    increased minimum ISO for pixels with better light gathering ability?
    And (make that two questions) if not, why can't a camera maker make a
    camera with an effective ISO of 25 so I don't have to buy ND filters to
    use wide-open apertures in bright light?

    Just wondering. I really think that if I ever realize that I will need a
    better camera than my 5D (and such a realization looks to be far into my
    future) I'd probably rather have 25 ISO, noise-free 1600 or 3200 ISO,
    faster frame rates, longer battery life, higher dynamic range, weather
    sealing and some other stuff than more pixels.

    Eric Miller

    rec.photo.equipment.35mm (keywords: "Canon" -phot mfg-, "5D" -35mm
    camera-, "ISO" -rel term-)
    rec.photo.digital (keywords: pixel -spec rel* term-, "Canon" -phot mfg-,
    "5D" -35mm camera-, "ISO" -rel term-)
    rec.photo.digital.slr-systems (keywords: pixel -spec rel* term-, "Canon"
    -phot mfg-, "5D" -spec rel* camera-, "ISO" -rel term-)
    Eric Miller, Aug 27, 2008
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  2. Eric Miller

    Paul Furman Guest

    Good question. I'm not sure either but one factor is CMOS has a lot of
    circuitry between the pixels compared to CCD which used to be a
    disadvantage as there isn't as much room for the wells (if I
    understand)but the microlenses allow at least taking full advantage of
    the surface area, if not the actual wells. It seems much of this
    technology is aimed at speeding up capture (a major advantage of that
    extra circuitry) whereas I rarely need fast capture and would generally
    prefer the best capture even if it was rather slow.

    I'm just guessing lower base ISO would mean lower max ISO. Not at all
    sure it's limited by anything other than that because P&S often have
    base ISO of 50 or so, right?

    Yeah, too many pixels is hell on the computer.

    Not that I really care but this seems off-topic for the 35mm group.
    Strictly a digital question :)

    Paul Furman

    all google groups messages filtered due to spam
    Paul Furman, Aug 27, 2008
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  3. Sorry, no.

    This post is off-topic for this newsgroup, rec.photo.equipment.35mm,
    which is concerned with film cameras that use 35mm film, not digital
    cameras that look like 35mm SLRs.

    Please use an appropriate newsgroup for postings on digital cameras. One
    of the following groups would be a good place for such postings:


    (Note that the list of groups available to you depends on what your ISP
    or news provider carries, and may differ from this list)

    "In 1964 Barry Goldwater declared: 'Elect me president, and I
    will bomb the cities of Vietnam, defoliate the jungles, herd the
    population into concentration camps and turn the country into a
    wasteland.' But Lyndon Johnson said: 'No! No! No! Don't you dare do
    that. Let ME do it.'"

    - Characterization (paraphrased) of the 1964 Goldwater/Johnson
    presidential race by Professor Irwin Corey, "The World's Foremost
    David Nebenzahl, Aug 27, 2008
  4. Eric Miller

    John Sheehy Guest

    The technology has been improving in such a way that there is no useful
    benefit in using it with lower pixel densities. By having an 8 MP 50D
    instead of a 15 MP 50D, you might (or might not) collect 5 to 10% more
    light, for a 2.4 to 4.7% decrease in shot noise, while the maximum
    resolution drops 26%. Not only the resolution drops, but the read noise
    at the entire image level increases, as for any given technology of
    readout, the read noise of the image as a whole is generally lower with
    higher pixel counts (or the read noise per unit of area is lower with
    higher pixel density). Currently, the 450D has the lowest ISO 1600 read
    noise per unit of area of any DSLR, including the D3 and the mk3 Canons,
    and it has the highest pixel density of them all.
    It very may well, but hidden from the user. Historical Canons have
    varied from about a native ISO 64 to about 115, but always marked 100 on
    the camera (the ones with a base ISO of 100). So, let's say the real
    base ISO of the 50D is 141 for the sake of argument; it will probably
    have a missing half stop of highlight headroom available at ISO 200.
    Canon is obsessed with starting ISOs at 50 or 100, when, in fact, they
    could start at 80 or 115 or 141 with future cameras with higher quantum
    efficiency. Sticking to simple number makes everything simpler on the
    surface, but really complicates matters, as they don't tell you that some
    of these low ISOs are missing highlight ranges available in higher ISOs.
    The mk3 cameras sport ISO 50, but don't deliver them as anything but ISO
    100 pulled one stop, with a missing stop of headroom.
    Because it would perform like crap at ISO 1600, and have no less noise at
    ISO 25 than current cameras have at ISO 100 or whatever their base ISO
    is. That is, until they invent a way to take multiple exposures with no
    blackout time between them, or find a way to fill the same photowell
    multiple times in an exposure.
    There will never be noise-free high ISOs. High ISO *MEANS* collecting a
    limited amount of photons per unit of area. There is no way to have high
    ISO and collect tremendous amounts of photons per unit of area. You will
    need much bigger sensors to get ISO 3200 image noise down even to the
    levels of current DSLR ISO 100. With current lens technology, that will
    also mean very big, heavy lenses, unless you want to surrender your high
    ISO to slow lenses.

    John Sheehy, Aug 27, 2008
  5. Eric Miller

    John Sheehy Guest

    Actually, at least some of the P&S sensors have base ISOs of 160 to 200, by
    DSLR standards (3.5 stops of headroom above metered grey). They are simply
    pulled a stop more than DSLRs are with their metering.

    John Sheehy, Aug 27, 2008
  6. Eric Miller

    Eric Miller Guest

    No, it's on-topic, otherwise, you wouldn't be reading this. You're not
    too bright are you?

    Eric Miller
    Eric Miller, Aug 27, 2008
  7. So you're saying that, ipso facto, because you posted it, therefore it
    must be on-topic?

    What impeccable logic! How can anyone argue with that?

    "In 1964 Barry Goldwater declared: 'Elect me president, and I
    will bomb the cities of Vietnam, defoliate the jungles, herd the
    population into concentration camps and turn the country into a
    wasteland.' But Lyndon Johnson said: 'No! No! No! Don't you dare do
    that. Let ME do it.'"

    - Characterization (paraphrased) of the 1964 Goldwater/Johnson
    presidential race by Professor Irwin Corey, "The World's Foremost
    David Nebenzahl, Aug 27, 2008
  8. Eric Miller

    Vagabond Guest

    Sorry yes.

    If I use a lens, a strobe, a filter or a technique, as I often do, that
    predates digital cameras, something I bought or learned for use with my
    SLR, it is still related directly to 35mm equipment. People who, like me
    use both film and digital, and mix and match equipment and techniques
    between the two, have a real interest in how such equipment or methods
    perform. For instance, a lens for a 35mm that had an average or even
    mediocre reputation with film, can sometimes be excellent with a digital
    camera that has a crop factor, as often the area where the lens
    underperformed might be in the areas that is "cropped".

    I have just discovered that a lens that I purchased for use with an SLR
    back in 1988 and then relegated to "emergency use only" for several poor
    performance reasons, now performs brilliantly with a cropped digital that
    doesn't use the offending corner areas. This is a valid point for
    discussion and related specifically to 35mm equipment. It adds value to
    such lenses for both the person who uses digital and the film only
    photographer who might own such a lens.

    You have an opinion, one that doesn't concur with many other photographer's
    opinions. You don't have the right to impose your opinion on those other
    photographers. By the same token, much of the nonsense that is cross
    posted is of little interest or concern to either type of photographer, but
    there is little that can be done about them as they have a right to be
    boring. A right that you apparently claim also with you pointless and
    incessant posts. Posts that only encourage more cross posts that are devoid
    of all photographic content, as is this one of mine.
    It is concerned with 35mm equipment, as is indicated in the title.

    If you wish to chase cross posting trolls, do so by all means, you are
    unlikely to anything but worsen the situation, but please don't try to do
    it by speaking for photographers like me who have a foot in both camps.


    Vagabond, Aug 27, 2008
  9. Eric Miller

    Eric Miller Guest

    Okay, bear with me on this one because I know that I am way over my head.
    Let me challenge your math and then you can correct me; hopefully my
    question will give a better idea of what is likely my misunderstanding. I'll
    use numbers that will resuly in an exact doubling of pixels, 8 and 16
    megapixels. A hypothetical 8 megapixel 50D (or any camera) should have
    "pixels" (photosites, etc.) that are exactly twice as large as the "pixels"
    on a 16 megapixel sensor, assuming that both sensors are the same size. I
    understand that not all of each "pixel's" "real estate" is taken up with the
    light collecting part; i.e., some of it is electronics. But, and this is
    where I may be wrong, if that site is doubled in size and doesn't need any
    extra electronics, can't all or almost all of the added space be used for
    the collection of light? Wouldn't that more than double the light collecting
    area (omitting, for the moment any discussion of microlenses)? So why only 5
    to10% more light collected by a photosite that is twice the size?

    I swear I don't think about this stuff when I am actually photographing

    Eric Miller
    Eric Miller, Aug 27, 2008
  10. But still more than you can resolve with the unaided human eye, and thus
    perfectly acceptable for viewing at any distance.

    PS. That image would be 250*ppi*. Your "twenty year old laserjet II"
    could only print a binary dot at 300dpi, not a 24-bit tricolour *pixel*.
    Rendering an almost acceptable 64 level grey scale with its native
    algorithm, the Laserjet II could only manage 37.5ppi monochrome,
    although some external stochastic algorithms could take this up to
    Kennedy McEwen, Aug 27, 2008
  11. Eric Miller

    SMS Guest

    One more thing I've noticed is that the worst offenders will often end
    up with new threads where they themselves are the subject. If there's
    anything worse than these people trolling, it's threads solely about
    their trolling!

    Hence it's often useful to not only kill-file the problem person's
    e-mail address, but to create a subect filter with their last name. I.e.
    someone started a thread complaining about Nebenzahl, with the subject
    "Challenge to David Nebenzahl." Adding "Nebenzahl" as a subect word
    filter eliminated all posts in this thread from appearing on my system,
    while adding "" as a "from" filter eliminated all
    posts from him. He trolls in non-photography groups as well, so I made
    sure them global filters.
    SMS, Aug 27, 2008
  12. Eric Miller

    Paul Furman Guest

    My ex still uses our 15 year old Canon Bubble-Jet BJ-200 black & white
    printer which is just a cheap little plastic thing. You can still get
    the ink cartridges.
    Paul Furman, Aug 28, 2008
  13. Eric Miller

    John Sheehy Guest

    Of each pixel, yes, but that is irrelevant, because you are not doubling
    the light collected by the sensor, or per unit of area.
    Maybe 5 to 10% more light collected by the *sensor*.
    That depends on what I'm photographing. Some things require 100%
    concentration between shots, and some give you lots of idle time.

    John Sheehy, Aug 28, 2008
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