1 stop of DR -how important it is and for what kind of photography

Started Apr 7, 2012 | Discussions thread
Safesphere
Regular MemberPosts: 149
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Re: JPEG is limited to 8 stops
In reply to DigVis, Apr 14, 2012

DigVis wrote:

My point regarding a photon existing at the point of emission, is that the energy quanta, represented by the photon, must have been created at this point. I would imagine that the energy loss at the emission point is measurable prior to the wave function collapsing, but for the case of light, I guess that also depends on how one defines relative time...

When a photon is emitted, we do not know much if anything about it until we detect it. Can you measure the energy lost by the emitter? Not precisely, because of the uncertainty principle. The uncertainty has nothing to do with our abilities or technical limitations. The energy (and most other parameters of the photon) is uncertain, because the photon simply does not have a certain energy. Or spin (in photographic terms, polarization), or phase (direction). In other words, it does not really exist as a particle until it hits your eye or the camera sensor. The uncertainty collapses on impact and all parameters obtain specific values. Again, it is not that the photon had these qualities and quantities, but we did not know them and got to know them by the measurement. No, the photon did not have specific characteristics, but obtained then at the moment of imact with the sensor. A better interpretation of this is that the emitter simply is a source of a wave, but the detector absorbs the particles.

Quantum mechanics is not understood, it is interpreted. It deals with the building blocks of nature that create our intuitive concepts. It is like trying to explain what a "brick" is by using only the terms of "building" and "city". About 20 different interpretations exist, some better than others. The above is one. Let me offer you another.

Yes you could interpret light as a beam of photons flying from the emitter to the detector, but with one caveat. If there are different possible routes, then each photon takes all possible routes at the same time. Furthermore, it takes them numerous times. For example, if one route is a million times more probable than the other, than the photon would take the first route a million times and the second route oly once, all of them at the same time. This is rather weird, so you may find the first interpretation easier to digest that what travels is a wave that collapses into photons upon detection.

Let me present an example relevant to photography. You may find this hard to believe, but it is true, and if anyone tells you otherwise, he does not know physics. Imagine you are taking a picture of a subject. Let it be a small candle for example. The lens focuses light from the candle onto the sensor. The light from the candle can take different routes. It could go through the optical center or through any other point. In fact, it goes through every point of the open aperture, but no matter where it went, it is then focused onto the same small area of the sensor where the image of the candle is. Nothing new so far.

Now imagine that light from the candle is so dim that you detect one photon at a time. What part of the lens aperture does one photon go through? Per our intuitive logic, the obvious answer is, the photon goes through one random point and the next photon would go through likely a different random point. But this is incorrect. The correct answer is that each individual photon goes through the entire open aperture of the lens.

Finally, the above assumption that we detect one photon at a time was made for simplicity and is irrelevant. When you normally take any picture, every photon flies through the entire surface of your lens that is not covered be the aperture. In other words, photons do not exist as particles, but travel as a smooth speadout wave until it collapses at the sensor. I hope this helps

So you mean that electrons do not exist at the point of emission either? How about superatomic particles (molecules). I thought it was shown that these can also exhibit wave properties?

Exactly the same as above. I know, your next question is, do airplanes exist before they land The heavier the flying object is, the shorter the wavelength is of its wave function. Shorter wavelengths are less prone to diffraction, they tend to keep closer to the straight line. In terms of quantum mechanics, the probability of a heavier particle to take a specific path is much higher than to take any alternative path. By the time you get to the size of anything visible in a microscope, the probability of any alternative path becomes virtually zero. Strictly speaking, quantum mechanics does not absolutely prohibit an airplane to fly through two different clouds at the same time, but the probability of this happening is low. There are over 100 billion stars in our galaxy. There are over 100 billion galaxies in the universe. If there were 100 billion airplanes on every planet around every star, you would need 100 billion universes before just one airplane does this once in 100 billion years. Not the exact number, of course, but just an illustration that you should not camp with a camera near an airport waiting for this to happen But strictly speaking, it is not impossible, as is going through the wall, etc. And when something like this happens, it is called a miracle. Quantum mechanics allows miracles, but not too often.

My idealized model had a cut-off of 0.5. So, a signal x (whether less than 0.5 or not) would read as 0 with probability 1-x.

Of course, the 0.5 cutoff works with +-0.5 noise, and the cutoff at 1 works with the 0-1 noise. However I am still pondering what happens if the noise distribution is not a step function, but a bell curve. I think you may still get truncation unless all noise (like within 3 sigma) is in the positive or else you allow a negative signal and negative cutoffs. But this probably has already nothing to do with digital photography.

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