MuratC
Forum Enthusiast
I think the DR of the new MkIII hasn't been discussed or speculated much. What does the first previews/tests say about its DR? Will it be better than the other 1D series/5D, etc?
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What about 1DMkIII's Dynamic Range?
- Thread starter MuratC
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Peter Carmichael
Leading Member
Erm. Opinions differ.
Douglas Brown
Leading Member
From the preview on the 1DIII on the Imaging Resource,
"For a lot of people, when they look at the specs for the Canon 1D Mark III, the first thing they'll focus on is that it has a couple more megapixels than the Mark II N before it. It turns out though, that the image quality story of the Canon 1D Mark III isn't just about the addition of a couple of extra megapixels, it's about delivering more megapixels, while simultaneously increasing dynamic range, increasing light sensitivity, and improving tonality. That's an achievement of quite another order."
"For a lot of people, when they look at the specs for the Canon 1D Mark III, the first thing they'll focus on is that it has a couple more megapixels than the Mark II N before it. It turns out though, that the image quality story of the Canon 1D Mark III isn't just about the addition of a couple of extra megapixels, it's about delivering more megapixels, while simultaneously increasing dynamic range, increasing light sensitivity, and improving tonality. That's an achievement of quite another order."
dnjake
Senior Member
The white paper said that the dynamic range would be about the same as the 1D Mark II. Of course, on occasion, Canon has underestimated DR in the past. We will have to wait for measurments on production cameras to see what it acutally is.
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Ken Phillips
Forum Pro
... whilst more bits may enhance the DISPLAY [by any means] of the data, it will NOT increase the number of stops of information captured. That is a finite amount. You can add a 128 bit A-D converter to an old 1D if you are clever enough ... but it won't help the DR.
An 8-bit camera could EASILY have better DR than a 16-bit unit.
KP
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An 8-bit camera could EASILY have better DR than a 16-bit unit.
KP
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Brad Chatellier
Well-known member
JackJosephJr
Leading Member
How does having more bits enable the camera to see higher highs and lower lows? Does a 16-bit Camera Raw conversion have more DR than one created in 8-bits? The number of steps in a set of stairs has no direct relationship in how high or low the staircase goes.
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thejaybird
Senior Member
andrewD2
Veteran Member
Its whether the DR captured is high quality.
Lower noise in the shadows and more tones in the highlights will give you higher quality dynamic range.
Greater ability to push the shadows and pull the highlights will have a marked effect on the apparent DR even if the luminosity range captured is the same.
Andrew
bicho
Forum Enthusiast
Could it not be that if there is more stairs on a ladder, then its easy to make the ladder longer (and, yes, make the steps bigger again)?
The PhaseOne P45 has a bit depth of 16 bits and a 12 stops dynamic range.
The PhaseOne P45 has a bit depth of 16 bits and a 12 stops dynamic range.
agreed.. I do want to see some b/w's out of the 1DMIII though...
however, they do manage to get some benefit out of the highlight protection which they do say gives another stop of possible detail. so I guess you could say that in wide variation of scenic data, the 1DMIII has the potental to capture more.
Ken Phillips
Forum Pro
Once we agree on criteria [especially as to what "acceptable noise" is] we can easily measure dynamic range.
We can take some test shots and show the difference with an 8-bit jpeg. Now just how is that possible?
It is entirely possible for a scene described in two bits to have more dynamic range than a scene that described in 128 bits. It may not be pretty, however.
Ken
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We can take some test shots and show the difference with an 8-bit jpeg. Now just how is that possible?
It is entirely possible for a scene described in two bits to have more dynamic range than a scene that described in 128 bits. It may not be pretty, however.
Ken
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Peter Carmichael
Leading Member
Here is the science. Whether the science is implemented well is another matter and I'll leave that to people with hands-on experience. This is a fairly simple treatment that doesn't consider pixel to pixel noise and color separation, but I'm hoping it is appropriate to add to the debate.
DR and noise go hand in hand. Noise is dominated by photon counting statistics (Poisson's law). The best way to save your shadows from disappearing into noise is to capture more photons. This gives you grief with the highlights blowing out, hence the need for a large full well depth.
The raw capture is digitized as a linear count of the charge accumulated in each photosite. This is proportional to the number of electrons stored. The number of electrons stored is proportional to the number of incident (and captured) photons.
Because the raw capture is a linear count directly related to incident photons, the dynamic range of the captured image can be limited by having too few bits available to digitize the available signal information. 14 bits stores two more stops of sensor data than 12 bits. Fact. Not fiction. That's just how it is.
In the least significant bits, quantization errors add noise. With bigger signals the digitization noise is insignificant compared to the inherent photon noise in the signal. At each signal level, there is a determinable photon shot signal to noise ratio. There is a measurable camera/digitization noise floor. There is a cut-off point at low signal levels after which the camera's readout noise swamps the signal.
The sensors in the last generation of big pixel Canon dSLRs (1DmkII and 5D) have large full well capacity at ~ 80000 electrons. If you are utilising the full well depth (ISO 100 typically for 5D and a bit less for the 1DmkII ref. PIXSurgeon), then the least significant bit of a 12bit RAW file reflects the charge of 20 electrons. This lowest level of information is subject to dither (intentionally added digital noise) to avoid artifacts. The photon shot noise at 20 electrons signal is equivalent to a bit less than 5 electrons. In other words, the digitization itself is introducing worse noise than the noise inherent in the original signal. Having 1 or 2 more bits available to the D/A conversion would add useful dynamic range in the capture.
I assert that 12 bit D/A holds back the 5D and the 1DmkII. I have an experiment that shows this.
This sensor-native DR capability on previous generation cameras is made available by use of the ISO setting, which alters the analogue amplification of the output signal. I have taken an "HDR" set of images with altered ISO setting (100,400,1600), but constant Tv and Av. I have an example HDR image here: http://www.seeminglyabsent.co.uk/2007_03_18_hdr/htmls/0000.html (Gallery of all shots is here: http://www.seeminglyabsent.co.uk/2007_03_18/htmls/IMG_8766.html
I have equalized the three contributing shots for brightness in post-processing, but look at the shadow noise in the dark window reflection and the highlights on the tiles on the right (gallery for shadows is here: http://www.seeminglyabsent.co.uk/2007_03_18_shadows/htmls/0000.html ; gallery for highlights is here: http://www.seeminglyabsent.co.uk/2007_03_18_highlights/htmls/0003.html )
Crops for shadows (ISO 100 -> 400 -> 1600)
Crops for highlights (ISO 100 -> 400 -> 1600)
By my reckoning, the improvement in shadows from ISO 100 to 400 is dramatic. This two stop variance in ISO setting would be available to a single shot with 14 bit conversion. The sensor has had this capability for a generation already; extra bits at the D/A stage are now making it possible to access this capability in post-processing of a single shot.
So. I would assert that 14 bit raw has the potential to add DR capability. If the full well depth of the 1DmkIII is still of the same order of magnitude as the 5D and 1DmkII, then the 14 bits will result in greater DR. The need to swing ISO to access this DR will reduce. The exact DR will depend critically on exposure.
DR and noise go hand in hand. Noise is dominated by photon counting statistics (Poisson's law). The best way to save your shadows from disappearing into noise is to capture more photons. This gives you grief with the highlights blowing out, hence the need for a large full well depth.
The raw capture is digitized as a linear count of the charge accumulated in each photosite. This is proportional to the number of electrons stored. The number of electrons stored is proportional to the number of incident (and captured) photons.
Because the raw capture is a linear count directly related to incident photons, the dynamic range of the captured image can be limited by having too few bits available to digitize the available signal information. 14 bits stores two more stops of sensor data than 12 bits. Fact. Not fiction. That's just how it is.
In the least significant bits, quantization errors add noise. With bigger signals the digitization noise is insignificant compared to the inherent photon noise in the signal. At each signal level, there is a determinable photon shot signal to noise ratio. There is a measurable camera/digitization noise floor. There is a cut-off point at low signal levels after which the camera's readout noise swamps the signal.
The sensors in the last generation of big pixel Canon dSLRs (1DmkII and 5D) have large full well capacity at ~ 80000 electrons. If you are utilising the full well depth (ISO 100 typically for 5D and a bit less for the 1DmkII ref. PIXSurgeon), then the least significant bit of a 12bit RAW file reflects the charge of
I assert that 12 bit D/A holds back the 5D and the 1DmkII. I have an experiment that shows this.
This sensor-native DR capability on previous generation cameras is made available by use of the ISO setting, which alters the analogue amplification of the output signal. I have taken an "HDR" set of images with altered ISO setting (100,400,1600), but constant Tv and Av. I have an example HDR image here: http://www.seeminglyabsent.co.uk/2007_03_18_hdr/htmls/0000.html (Gallery of all shots is here: http://www.seeminglyabsent.co.uk/2007_03_18/htmls/IMG_8766.html
I have equalized the three contributing shots for brightness in post-processing, but look at the shadow noise in the dark window reflection and the highlights on the tiles on the right (gallery for shadows is here: http://www.seeminglyabsent.co.uk/2007_03_18_shadows/htmls/0000.html ; gallery for highlights is here: http://www.seeminglyabsent.co.uk/2007_03_18_highlights/htmls/0003.html )
Crops for shadows (ISO 100 -> 400 -> 1600)
Crops for highlights (ISO 100 -> 400 -> 1600)
By my reckoning, the improvement in shadows from ISO 100 to 400 is dramatic. This two stop variance in ISO setting would be available to a single shot with 14 bit conversion. The sensor has had this capability for a generation already; extra bits at the D/A stage are now making it possible to access this capability in post-processing of a single shot.
So. I would assert that 14 bit raw has the potential to add DR capability. If the full well depth of the 1DmkIII is still of the same order of magnitude as the 5D and 1DmkII, then the 14 bits will result in greater DR. The need to swing ISO to access this DR will reduce. The exact DR will depend critically on exposure.
Peter Carmichael
Leading Member
There have been a few posts in the meantime. My gut instinct tells men that Ken is wrong, but I might be missing something. My attempt at describing the science I think suggests that 14 bit takes us to the limit for a 5D-like sensor technology. My example I think backs this up. I think my example also shows that 16 bit (12 bit with a 4 stop swing of ISO) is well beyond 5D-like sensors.
I don't want to stifle debate. I hope my example provokes (sensible) debate.
I don't want to stifle debate. I hope my example provokes (sensible) debate.
No, it's the other way round. If the ladder is longer, you need more steps or the steps become too large. IF a sensor has more dynamic range, you need a higher bit depth to translate that range into meaningful bits. But if the sensor doesn't, there is no gain in increasing the bit depth.
Turn it around. The PhaseOne has 12 stops dynamic range, so it made sense to give it more bit depth.
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