Why not? What if the sensor accumulates exactly zero photoelectrons?But it cannot...
You cannot avoid that problem without treating signal quantization as a sort of sensor's nonlinearity by itself.
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Why not? What if the sensor accumulates exactly zero photoelectrons?But it cannot...
The practical problem would seem to be constructing the ADC to return a bit value if no photons are detected. Wouldn't a simple "if measured value is less than n photons, then return 0" get you out of the theoretical box?Why not? What if the sensor accumulates exactly zero photoelectrons?
You cannot avoid that problem without treating signal quantization as a sort of sensor's nonlinearity by itself.
It practically is doable, but then we get a theoretical infinity in our definition of "DR".The practical problem would seem to be constructing the ADC to return a bit value if no photons are detected.
Then our sensor is not linear anymore, and the chosen value of n will determine its DR.Wouldn't a simple "if measured value is less than n photons, then return 0" get you out of the theoretical box?
Why not? What if the sensor accumulates exactly zero photoelectrons?
You cannot avoid that problem without treating signal quantization as a sort of sensor's nonlinearity by itself.
That would mean that the DR of your sensor is 7 stops.It's not possible, there's no physical systems without noise. As far as I understand, zero value after applying 7 hi ADC represents the noise level or is close to it. After a 14-bit ADC, the highest value 16383 has to be interpreted as 14 stopsbrighter than the lowest value and all values are linear (raw files are gamma 1.0).
The number of electrons and therefore the voltage in a pixel is a linear function of number of photons, and the voltage is then converted to a digital value via ADC. Now with the steps, they're normally defined as the smallest detectable level of the signal, effectively the noise, and the DR is defined as max level/noise level, so by definition a linear ADC can't produce a DR larger than its bitness.
That would mean that the DR of your sensor is 7 stops.
However, you are mistaken in the assumption that the level of noise does not depend on the level of the signal. When we are talking about photon shot noise, a signal with full 14 bits of value will be accompanied with ~7 bits of noise; a much lower signal with 8 bits of value will be accompanied with ~4 bits of noise, and a total darkness (a signal with all bits equal 0 on a linear sensor) will have no photon shot noise at all (there will still be dark current noise, of course, but t can be very small and not flip the lowest bit most of the time).
There's no "voltage" collected by a pixel, there is an amount of energy properly defined as a charge. Photons vibrating at different wavelengths of light release slightly different amounts of energy when they are absorbed by a photosite. The full well capacity of many cameras is well beyond the maximum number of steps possible with 14 bits. The EOS 1D X, for instance, has FWC of over 90K electrons, which requires 17 bits to allow a unique digital value for each increase of one electron. That's 5.5X more information than can be expressed in 14 bits.
Yes, but after ADC the limiting factor is the bitness of the ADC, which was my original point.
But the bitness only limits the distance between each step for the same total distance between "0" and 2^n - 1. It doesn't require that each doubling of the number of steps means a doubling of the total brightness between "0" and 2^n - 1. A 2:1 or 1:2 slope is still just as linear as a 1:1 slope is.
That could help sometimes. Often for macro, you want the lens left alone and the camera moved on a rail.In addition to the features already mentioned for the 5D Mark V the addition of focus bracketing would be very useful for in field macro photography. If it has this feature and some increase in resolution among other improvements I would upgrade from my 5D mark IV.
All the papers I've read so far on digital sensors point out they're linear. A single pixel can have more than 14 stops of well capacity, but it's then clamped and converted lineary in ADC. So the number of bits in ADC is the upper bound for the resulting dynamic range.
The full well capacity of many cameras is well beyond the maximum number of steps possible with 14 bits. The EOS 1D X, for instance, has FWC of over 90K electrons, which requires 17 bits to allow a unique digital value for each increase of one electron. That's 5.5X more information than can be expressed in 14 bits.
An "ideal" one does.I don't think the ADC spits out a unique digital value for every single-electron increase.
ETTR is a thing mostly because while the absolute shot noise is directly proportional to the square root of luminous energy, the relative shot noise is inversely proportional to the square root of luminous energy.ETTR is a thing precisely because it maximizes the tonal steps as there are more steps dividing the highlight stops than the shadow stops.
ETTR is a thing mostly because while the absolute shot noise is directly proportional to the square root of luminous energy, the relative shot noise is inversely proportional to the square root of luminous energy.
Probably because the early non-FF digital cameras were really poor at it?When ETTR first hit sites like LL, any benefits related to noise or shadow push were mentioned as a side note if they were mentioned at all. It was all about tonal separation, which is an observable benefit.
At best, subtractive colors on a piece of paper will not have a great dynamic range.No, we were talking about specific DR measurement method from http://www.photonstophotos.net/Charts/PDR.htm
Those charts don't tell you the maximum you could pull out of your raw files. The charts are based on a model where you print the image on 8"x10" paper and view it from a certain distance (I understand it's just the math model - they don't actually print the images).
So it seems that practically these are imaginary numbers (neither in screen nor in paper)! The real DR is less for all camera models.At best, subtractive colors on a piece of paper will not have a great dynamic range.
So it seems that practically these are imaginary numbers (neither in screen nor in paper)! The real DR is less for all camera models.
If you consider them as the origin of the signal, then yes.At best, subtractive colors on a piece of paper will not have a great dynamic range.