lens vs. image sensors in digital photgraphy

Discussion in 'Digital Photography' started by aniramca, Dec 9, 2006.

  1. aniramca

    J. Clarke Guest

    You're not very good at reading what others wrote before you engage
    your script, are you? There is absolute proof that they are good enough
    for engineering and navigation. This is not the same as there being proof
    that the assumptions on which they are based are correct and in fact the
    equations used for engineering and navigation are not only an
    approximation but they are known to be an approximation to a more accurate
    model and the degree of their error is known.
    Roger, you don't know enough to understand the problem if you think that
    using "fundamental physics equations" guarantees an accurate solution.
    But the fact that your knowledge of mathematical physics is at a level
    where a site such as that will impress you says much.
    Oh, GAWD. Roger, you've been sold a bill of goods if you are taking your
    information from that web site.
    For decades? And how exactly have we been doing this?
    Again you're oversimplifying some complex research. You're asserting that
    studying mars and venus is telling us how changes in carbon dioxide levels
    affect temperature. To do that we would need to be monitoring changes in
    those levels on Mars and Venus and measuring temperatures. There is no
    program in place to do that and no method by which the surface
    temperature of Venus may be measured other than by direct observation. So
    again you're oversimplifying complex research. Venus is hot, venuse has a
    lot of carbon dioxide, therefore carbon dioxide is bad seems to be your
    So you admit that there is a problem with climate models but you are going
    to rush off into precipitate political action based on them regardless.
    This is assuming that the solar flux dropping is the cause of ice ages,
    which is again something that is not proven, it's speculation, and the
    models that purport to "prove" it doen't correlate well with the observed
    data. And again you're ignoring that ice core, which shows that we
    _should_ be well into a period of deep glaciation by now, not a "mini ice
    age" but the real deal. Something is stopping it and if that something
    isn't human activity then something has changed in the climate and if that
    something isn't human activity then we don't have a clue what it is or
    where it's going to go.
    The problem with "the data" is that absent a model you don't know what the
    data is telling you. And if you have the wrong model then the data is
    telling you the wrong thing.

    By going with "the data" you are in fact making up your own model,
    apparently a linear extrapolation beyond the range of validity of the data,
    and assuming that that model is valid. This is always a risk in science
    and in engineering. Any engineer with any real experience has gotten
    burned this way at least once.
    J. Clarke, Dec 22, 2006
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  2. aniramca

    J. Clarke Guest

    And yet that's all we are now is "a bunch of humans huddling over a
    campfire". How many humans and how many campfires does it take before you
    have a greenhouse effect and on what information do you base this
    J. Clarke, Dec 22, 2006
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  3. aniramca

    J. Clarke Guest

    I can't tell if you misread something, don't understand the word
    "climate", or are just plain _nuts_.

    Suppose I have infinite money. How does that change the climate? Suppose
    I have no money. How does that change the climate? What do you believe
    a "climate" to be?
    J. Clarke, Dec 22, 2006
  4. I mostly go by this definiton of "climate":

    "the average course or condition of the weather at a place usually
    over a period of years as exhibited by temperature, wind velocity, and

    This is something which I think can be affected by the use of CO2
    emitting fuels in the long term. Hopefully this clears things up!
    Toni Nikkanen, Dec 22, 2006
  5. aniramca

    J. Clarke Guest

    No, it doesn't because it doesn't demonstrate any fashion in which the
    price of fuel affects the climate. However if you think that we need to
    stop using fossil fuels in order to improve the climate then I would
    expect you to welcome the prospect of running out of them.
    J. Clarke, Dec 22, 2006
  6. aniramca

    prep Guest

    No it does not, it only cycles it rapidly.

    Paul Repacholi 1 Crescent Rd.,
    +61 (08) 9257-1001 Kalamunda.
    West Australia 6076
    comp.os.vms,- The Older, Grumpier Slashdot
    Raw, Cooked or Well-done, it's all half baked.
    EPIC, The Architecture of the future, always has been, always will be.
    prep, Dec 22, 2006
  7. aniramca

    Aaron Guest

    Gosh, you're right, they could all be wrong! I suppose, since it's
    *conceivable* that global warming is imaginary, we should continue to
    live like gluttons, pumping as much chemical byproduct into the
    atmosphere as we see fit; anything to keep our Escalades rolling and
    the thought of environmental responsibility as far from our minds as

    If 99 years of automobiles and (conservatively) 150 years of
    industrial production and pollution haven't had a palpable effect on
    our global climate (as J. Clarke claims), than halting--or at least
    mitigating--these pollutants will not have as drastic a reverse
    effect. Is there any reason why we shouldn't? For the sake of luxury?

    Whether global anthropogenic climate change is a reality or a
    falsehood, we should take a moment to step back and truly examine our
    environmental situation. The Kyoto Protocols were poorly executed
    calls to action, but that doesn't mean we should close our eyes and go
    on our merry way, no thought paid to the ways you and I personally
    pollute our atmosphere every day.
    Aaron, Dec 22, 2006
  8. aniramca

    prep Guest

    Are you refering to Methane? If the tundras thaw enough to start rotting
    and fermenting,...

    Paul Repacholi 1 Crescent Rd.,
    +61 (08) 9257-1001 Kalamunda.
    West Australia 6076
    comp.os.vms,- The Older, Grumpier Slashdot
    Raw, Cooked or Well-done, it's all half baked.
    EPIC, The Architecture of the future, always has been, always will be.
    prep, Dec 22, 2006
  9. aniramca

    Bill Funk Guest

    Reasonable question.
    Supposition, not supported.
    Which has zip-all to do with the climate.
    Bill Funk, Dec 22, 2006
  10. aniramca

    Bill Funk Guest

    No, he's referring to water vapor.
    Bill Funk, Dec 22, 2006
  11. I'm not entirely sure what you mean by the 'most important'. Certainly, methane
    is about 10 times more effective at trapping solar heat than is CO2, but
    currently we release far less methane than CO2 into the atmosphere. Further,
    water vapor, undoubtedly because of its abundance, currently traps more heat
    than CO2 does. Do you see why I'm not certain what you are asking?

    Back to methane - there are vast amounts of it trapped in the permafrost in the
    Lake Baikal region. Should all of that permafrost thaw (as it appears likely it
    will) and release the currently bound methane to the atmosphere the consequences
    to global warming will be staggering. That alone might be enough to tip the
    concentration of greenhouse gases in the atmosphere to beyond the point where
    anything we can do might save us. It seems that far from being adherents of the
    Chicken Little approach, our specialists have been overly cautious in their
    estimates of the current and increasing danger to us from global warming. It is
    certainly fact that our planet is warming rapidly, even more rapidly than first
    estimated. And it is also certain that the consequences to all of us are even
    more dire than initially predicted.

    Partly to bring this back on topic, and also to provide a graphic illustration
    for those who stubbornly refuse to believe the planet is warming rapidly, there
    is an interesting project involving photographs of the glaciers in Glacier
    National Park (in the US state of Montana), some taken near the beginning of the
    previous century and others made more recently. Some of these are available at
    the USGS Web site, and provide stark illustration of the ongoing effect of
    planetary warming. The link below is to the Grinnell Gallery of some of these

    There is much more equally valuable information available on the site. Surfing
    around within it is well worth the time of anyone seeking a better understanding
    of what el Busho and cronies have repeatedly called 'junk science'.
    maxsilverstar, Dec 22, 2006
  12. The human population as exponentially increased, and the amount
    of fuel burning is increasing every year. A few hundred
    years ago and longer, the fuel use was negligible compared to
    today's industrial age. The amount of fuel used is well
    cataloged by country. e.g. see:
    United States Energy and World Energy
    Production and Consumption Statistics

    Some searches will find web sites that show other historical

    Roger N. Clark (change username to rnclark), Dec 23, 2006
  13. This started when smb called global change research junk science.
    I objected. You may have noted from my other posts that
    I don't agree with all global change research, but not that
    it is junk science; rather it is excellent and evolving
    science, and still has a ways to go. But that doesn't mean
    we haven't learned some very important things along the way,
    or that some things haven't become clear. I'll elaborate on this
    in other responses I'll shortly post.
    In my experience, those opposing the message of global change
    seem to have their objection based on economic reasons.
    E.g. doing something will cost that person money, or
    harm "the economy." I agree, prices of fuel has zip to
    do with climate, but everything to do with changing actions
    that could change man's effect on climate.

    Roger N. Clark (change username to rnclark), Dec 23, 2006
  14. Actually that is not the case. There are problems surfacing with
    spacecraft navigation that remain unexplained. For example,
    google: pioneer anomaly NASA
    and see articles like:
    The Problem with Gravity: New Mission Would Probe Strange Puzzle

    There have been scientific conferences on the subject.

    Then google: speed of gravity
    and see more strange things.
    I gave you a link to show simple equations. My field is
    planetary science and I do radiative transfer calculations
    routinely in my work. I can give references to
    more rigorous equations regarding climate models, but unless
    you have membership in the various societies, you'll likely
    find you have to pay $30 per article (something I think is
    very bad for scientific research in general and bad for public
    access to information largely funded by public dollars).

    Here is one reference that is online:

    Clark, R. N., Chapter 1: Spectroscopy of Rocks and Minerals,
    and Principles of Spectroscopy, in Manual of Remote Sensing,
    Volume 3, Remote Sensing for the Earth Sciences,
    (A.N. Rencz, ed.) John Wiley and Sons, New York, p 3- 58, 1999.

    For equations of radiative transfer theory, see this section:
    The Chandrasekhar equations provides the fundamental radiative transfer
    theory for planetary atmospheres, stellar atmospheres, and
    light interacting with solids, including planetary surfaces.
    The Chandrasekhar H-functions are integral equations (the integrals
    are not shown because "everyone" in the field knows what they are).

    These equations and the theory are not perfect but do a very good job.

    Look at Figure 3b to see the infrared transmission of the earth's
    atmosphere and with CO2 doubled. Then note the figure caption which
    describes what most of the absorption is due to.
    You can easily search for more comprehensive science articles and
    pay the dollars to access those articles.
    Common issues with complex models are how they behave as variables
    get extended. A good model will predict accurately those unusual
    conditions. Including Venus, Mars and Titan into climate models
    helps validate those models over larger ranges of conditions.
    And guess what, they are working and predicting what we observe
    on those bodies. The same basic radiative transfer equations are
    also used in modeling stellar atmospheres.

    Concerning measuring the surface temperature of Venus, yes it
    is being done with infrared spectroscopy. For example, one paper
    on which I am a co-author:

    Baines, K.H., G. Bellucci, J.P. Bebring, R.H. Brown, E. Bussoletti,
    F. Capaccioni, R. Cerroni. R.N. Clark, A. Coradini, D.P. Cruikshank,
    P. Drossart, V. Formisano, R. Jauman, Y. Langevin, D.L. Matson,
    T.B. McCord, V. Mennella, R.M. Nelson, P.D. Nicholson, B. Sicardy,
    C. Sotin, G.B. Hansen, J.J. Aiello, and S. Amici (the Cassini
    VIMS team), 2000, Detection of sub-micron radiation from the
    surface of Venus by the Cassini/VIMS: Icarus, 148, 307-311.

    (In case you don't understand the title, sub-micron radiation
    refers to heat from the surface at wavelengths less than 1-micron,
    because the surface is so hot.)

    References in that paper illustrate the historical work. At the
    American Geophysical Union meeting earlier this month in San
    Francisco, new maps of Venus' surface were presented using
    near infrared wavelengths, directly sensing the heat from
    Venus' surface.
    Yes, there are problems with climate models. No model is perfect,
    not any theory (although Einstein was pretty certain of his, and
    it seems so far Relativity may be an exception). ;-)
    But just because a model and theory is not perfect does not
    mean that it is not useful. If you didn't believe in any
    theory, you couldn't believe that anything in the world would work,
    including starting your car, or turning on a light.

    No, it may have yet another solar cycle on the vast scheme of things.
    We do have data on multiple solar cycles. There is an
    11-year sunspot cycle, 22-year cycle, then longer cycles that
    amount to several hundred years (e.g. see Maunder minimum).
    There are whole books written on this subject, and many science
    papers. A quick google search will show many, e.g. a 188-year
    cycle: http://arxiv.org/abs/astro-ph/0606426
    Often a simple model tells you the majority of what you need to know.
    For example, everyone can form a model of sunrise and sunset times
    by observing for a few years: the sun rises earlier in summer than in
    winter. If you develop a complex math model for describing the
    times of sunrise and sunset using orbital mechanics, you'll
    find it doesn't work precisely. The reason is that atmospheric
    refraction changes the apparent position of the sun, changing the
    time of sunrise. To get very precise, you need temperature,
    pressure, and atmospheric composition (water is quite variable)
    over the line of site for each sunrise and sunset, a very difficult
    set of measurements to obtain and feed real time into your model
    to get the exact time the sun hits the horizon. Then throw
    in a mountain too. But for the basics, you don't need all that,
    and we live our lives each day knowing the simple model of
    the approximate time the sun rises is good enough.

    Same with climate models. The models are well refined enough,
    and the data clear enough to know the effects happening.
    The trends are clear.
    No. As I stated above, Mars, Venus, and Titan provide outer
    bounds way beyond earth parameters that help show the models
    work over wide ranges of conditions. And stellar atmospheres too!
    We now have decades of development of climate science, by
    many scientists all over the world. The competition for improvement
    is fierce. One thing the public seems to not understand about
    scientists: they are brutal on each others theories. One
    can become famous by ripping apart someones else's models and theories
    and putting your own out front. And it is that competition
    that makes science so great and with time, and so robust, even though
    it is never perfect. The major journals science and nature
    publish mostly the top discoveries, many of which are finding
    some previous model/prediction/theory inadequate and/or wrong.

    The climate literature has refined beyond the basics and is
    providing a consistent picture. And the data are becoming
    clearer too, as the effects become stronger.

    Roger N. Clark (change username to rnclark), Dec 23, 2006
  15. aniramca

    smb Guest

    Some aspects of "global change research" is indeed junk science,
    particulary when politicians use incomplete data to draw conclusions
    that help them get elected. There's also some good science behind it,
    but nothing there that would force people to make the kinds of radical
    changes in their lives that would be required to reverse the effects
    of human-caused climate change, if that really exists.

    "Economic Reasons" mean much more than paying more for gasoline at the
    pump. The kinds of economic changes required by a knee-jerk reaction
    to global warming would put entire countries into economic tailspin.
    The politics of global warming are such that the developing nations
    would be quite happy to see the industrial nations self-destruct from
    economic depression while they take a more prominent position in the

    Again, what are YOU willing to sacrifice to reverse global warming if
    the doomsayers are correct? Your job? Your car? Your house? Your
    easy access to inexpensive food? Your cameras? Your freedom to
    travel anywhere in the world you choose? How about all of the above
    for every other citizen?

    smb, Dec 23, 2006
  16. aniramca

    J. Clarke Guest

    When it stops evolving, _then_ it's time to start acting on the results.
    Well perhaps if you actually responded to what I wrote instead of giving
    me canned answers that go off on irrelevant tangents I might think that
    you were conversing instead of preaching.
    J. Clarke, Dec 23, 2006
  17. aniramca

    J. Clarke Guest

    You have records that go back 10,000 years? Do tell.
    J. Clarke, Dec 23, 2006
  18. There are quite reasonable estimates, and once you go back
    far enough, the numbers are so low as to be insignificant,
    especially considering people's impact on the global
    environment. For example, with current population of
    6 billion people, around 1 AD it was only about 150
    million, or 40 times less. Thus even if the industrial
    output per capita were the same as today, the impact
    would be 1/40 of today's impact on the environment.
    And because industrial output was much less, the impact
    would be much less. So 10,000 years ago the population
    is negligible compared to today's billions.
    And current population is doubling about every 58 years.
    Kinda scary if you want to get out by yourself to do
    some photography ;-).

    Here is a cool website showing the population growth
    as a function of time on a world map:

    Roger N. Clark (change username to rnclark), Dec 23, 2006
  19. The only speculation is by those denying warming is real. The
    evidence is overwhelming that the earth is warming, and from
    multiple lines of evidence. The controversy is really what fraction
    of that warming is caused by people and what proportion of each
    cause is contributing to the total effect.
    You apparently don't understand the scientific process. It is certainly
    true that a bad paper can be published, or papers with mistakes,
    but it is also interesting to see the rapid response corrections
    and counter papers published. Scientists make their careers on
    being correct, and seem to delight in ripping someone else's
    work apart, in order to become king of the nerd hill for a while.
    It is a system that works well. Much like the back and forth
    discussions in these newsgroups, science discussions are played
    out in the scientific literature in the form of letters to the
    editor, gray literature (e.g. institution publications), peer-reviewed
    journals, and more recently web sites. Until web sites, this
    interaction took months to years in the paper publication
    There will never be conclusive proof in some people eyes.
    The question is what constitutes enough evidence to convince
    you or me, or someone else?
    This is a great example of the scientific process. Some scientists
    came out and said the earth would suffer global cooling.
    But others stepped in and analyzed more data and refined the
    models and found those scientists were wrong. That happened
    decades ago. Since then more data, more research, more refined
    models, and the answer keeps coming up the same:
    global warming is happening and we are getting refined data
    and answers to determine the causes of that warming.
    Initially, some scientists said it was all due to people.
    Others stepped in and should that was not the best answer and
    showed the sun is varying and contributing to the warming.
    (Did you know Mars' polar caps are also shrinking?).
    So the scientific process is working very well indeed.
    Decades of research are overwhelmingly point to warming.
    Evidence is becoming clearer that a portion of that warming
    is due to people. What the exact fraction is is what
    is currently being discussed the scientific literature.
    Excellent! Correct.
    This is an interesting read and raises interesting issues. But I note
    you are focusing on CO2 and as outlined in the above link, there
    are numerous sources causing the warming. Then also notice, no one
    is talking about whether warming exists or not, but the relative
    contributions of each source.

    It is also of interest to note in the above web exchange that
    there is little discussion of water vapor, the gas causing the
    most warming. It is ignored because it "is not a well mixed
    gas." Another reason is that it is so variable and there
    are no good measurements of it in the historical record. That
    makes it difficult to include in the models. Hmmm....
    Certainly if there was no sun, we would all freeze, and certainly
    the sun is the major cause of warming. The changing sun is now
    pretty well established, and is being precisely measured and
    included in models.
    "The Day After Tomorrow" was really bad in my opinion.
    The freezing thing was totally absurd.
    1) education.
    2) I do make fundamental measurements on material properties.
    A fundamental parameter in the heat balance equation is the
    albedo (reflected) of the earth's surface. For any spot
    on the earth, that albedo changes as a function of incident light.
    Climate models need to include this.
    You are over reacting. We need to change by developing better
    technologies that are less polluting. We (people in many
    nations) are doing that, but is the rate fast enough?
    For example, Europe is way ahead in developing wind farms.
    There are many technologies and are "cleaner" and cost nominally
    more. Where I live (Colorado) we voted to mandate (at increase
    taxes) a higher percentage of renewable energy, including wind
    and solar. I have solar cells now, even one on my car
    (a custom thing), and will continue to invest in that direction.
    Yes, sea level rise is increasing, yet another factor in the growing
    list of indicators of warming. The rise was about 0.15 mm/year
    for ~3000 years, then 1 to 3 mm/year since about 1900,
    and higher (3-4mm) today. (long term historical data from
    tide gages and geologic records, latest from satellites)

    Here are data from precise satellite measurements:


    from 1995 to today sea level has risen about 40 mm.
    When the oil runs out, will the naysayers adapt or die out?
    Others will have converted to solar/other long before that. ;-)

    On the positive side for the photographic thread, if the solar
    flux is increasing, we'll all be able to use shorter exposure
    times. On the negative side, the higher temperatures will
    mean more thermal noise in our digital camera images.

    Roger N. Clark (change username to rnclark), Dec 23, 2006
  20. aniramca

    smb Guest

    I don't deny that the data show a warming trend. My objection is the
    politicization and overreaction before knowing exactly what is
    happening and why. Again, the earth has warmed and cooled
    considerably over the eons. There's nothing new under the sun. We
    can measure things better these days, but that's no need to go off

    Exactly. Much of what used to be considered scientific fact is
    sometimes just the product of oversized egos.

    The bigger issue is how we react to inconclusive and sometimes
    contradictory data. IMO, even if the data conclusively prove that
    the earth is in a prolonged warming cycle, I don't think there's a
    thing we can do about it short of preparing for warmer weather.

    The problem is when people like Al Gore take what is merely being
    discussed, present it to the public as fact, then push for regulations
    that will seriously harm the economic well-being of the population.

    Do I get a green Earth Day sticker for my forehead? ;-)

    Exactly. I think when all the dust settles we'll find that the Sun
    is by far the greatest contributor.
    Amen to that.

    But all the education and measurement in the world isn't going to
    change a process with planetary inertia behind it. It may make more
    people aware of it, that's all.

    That's not overreacting at all if indeed global warming is disasterous
    and it is caused by human activity. If we are really responsible for
    what is happening, merely reducing things won't do anything to reverse

    The little things you do are symbolic, that's all. Try telling the
    developing countries that they have to forego fossil fuels because
    scientists in the developed countries have decided it's bad for the
    planet. That ain't going to happen.
    And I just saw on the news that the first inhabited island was
    officially lost to rising sea levels. So this is happening. Now,
    will wind farms and hybrid cars do anything to bring that island back?
    Those who live on the coasts would do better for themselves to invest
    in some inland property rather than solar cells on their roofs.

    The conversion to alternate forms of energy will be driven by
    economics, not by people feeling they are saving the planet. When
    the oil truly starts to run out, the free enterprise system will do a
    very nice job of bringing those sources of energy to market.

    It's interesting that there are those who believe that oil is actually
    a renewable resource produced deep under the surface, and as evidence
    they point to oil fields that they thought had been running out
    mysteriously refilling. Hmmmm.....

    Yes, always look on the bright side! Me, I'm looking forward to not
    having to retire to Florida if Florida will be brought to me...

    smb, Dec 24, 2006
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